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Online Questions & Answers in Ophthalmology in the simplest way. Dr. Di Giovanni’s Eye Center.

Ophthalmological web couseling by Dr. Alfredo Di Giovanni's Eye Center Naples, Italy.

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Dr. Alfredo Di Giovanni's Office is in Naples, Italy. Beyond the normal clinical activity Dr. Di Giovanni takes up an intense activity of web advising for national and international patients. Beyond general Ophtalmology, he is specialized in excimer laser surgery (correction of myopia, hypermetropia and astigmatism with Laser: PRK - LASIK - LASEK), Glaucoma (specific visits and tests for diagnosis and therapy), Pediatric Ophtalmology (visual defects and strabismus in children).
Dr. Alfredo Di Giovanni is, moreover, specialized in Uveitis and Corneo-Conjunctival Pathology (diagnosis and therapy of inner inflammations of the eye, diagnosis and therapy of allergic, infectious and hyposecretive conjunctivitis; diagnosis and therapy of corneal pathologies; laboratory examinations for manifold pathologies of the Cornea and the Conjunctiva).
Dr. Alfredo Di Giovanni's Eye Center provides, moreover, a corneo-conjunctival counseling service for Ophthalmologists.
Dr. Alfredo Di Giovanni, is Professor of Conjunctival Pathology at the Ophthalmic Department of the University of Ferrara.




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Conjunctivitis is an inflammation of the conjunctiva (the outermost layer of the eye and the inner surface of the eyelids), often due to infection. There are three common varieties of conjunctivitis, viral, allergic, and bacterial. Viral and bacterial conjunctivitis are contagious. Other causes of conjunctivitis include thermal and ultraviolet burns, chemicals, toxins, overuse of contact lenses, foreign bodies, vitamin deficiency, dry eye, dryness due to inadequate lid closure, exposure to chickens infected with Newcastle disease, epithelial dysplasia (pre-cancerous changes), and some conditions of unknown cause such as sarcoidosis. Blepharoconjunctivitis is the combination of conjunctivitis with blepharitis. Keratoconjunctivitis is the combination of conjunctivitis and keratitis. An eye with Viral conjunctivitisContents Epidemiology Diagnosis Symptoms Signs Differential diagnosis 4 Investigations 3 Treatment 4 External links Epidemiology Viral conjunctivitis is due to spread by aerosol or contact of a variety of contagious viruses, including many that cause the 'common cold', so that it is often associated with upper respiratory tract symptoms. Clusters of cases have been due to transfer on ophthalmic instruments which make contact with the eye (eg, tonometers) and not adequately sterilised. Allergic conjunctivitis occurs more frequently among those with allergic conditions, with the symptoms having a seasonal correlation. It can also be caused by allergies to substances such as cosmetics, perfume, protein deposits on contact lenses, or drugs. It usually affects both eyes, and is accompanied by swollen eyelids. Bacterial conjunctivitis is most often caused by pyogenic bacteria such as Staphylococcus or Streptococcus from the patient's own skin or respiratory flora. Others are due to infection from the environment or from other people, usually by touch (especially in children), but occasionally via eye makeup or facial lotions. Irritant, toxic, thermal and chemical conjunctivitis are associated with exposure to the specific agents, such as flame burns, irritant plant saps, irritant gases (eg, chlorine or hydrochloric acid ('pool acid') fumes), natural toxins (eg, ricin picked up by handling castor oil bean necklaces), or splash injury from an enormous variety of industrial chemicals, the most dangerous being strongly alkaline materials. Xerophthalmia is a term that usually implies a destructive dryness of the conjunctival epithelium due to dietary vitamin A deficiency - a condition virtually forgotten in developed countries, but still causing much damage in developing countries. Other forms of dry eye are associated with ageing, poor lid closure, scarring from previous injury, or autoimmune diseases such as rheumatoid arthritis, and these can all cause chronic conjunctivitis.Diagnosis Symptoms Redness, irritation and watering of the eyes are symptoms common to all forms of conjunctivitis. Itch is variable. Acute allergic conjunctivitis is typically itchy, sometimes distressingly so, and the patient often complains of some lid swelling. Chronic allergy often causes just itch or irritation, and often much frustration because the absence of redness or discharge leads to accusations of hypochondria.Viral conjunctivitis is often associated with an infection of the upper respiratory tract, a common cold, or a sore throat. Its symptoms include watery discharge, variable itch, and the fact that the infection usually begins with one eye, but may spread easily to the fellow eye. Bacterial conjunctivitis due to the common pyogenic bacteria causes marked grittiness/irritation and a stringy, opaque, grey or yellowish mucoid discharge (gowl or other regional names) that may cause the lids to stick together (mattering), especially after sleeping. However discharge is not essential to the diagnosis, contrary to popular belief. Many other bacteria (eg, Chlamydia, Moraxella) can cause a non-exudative but very persistent conjunctivitis without much redness. The gritty feeling is sometimes localised enough for patients to insist they must have a foreign body in the eye. The more acute pyogenic infections can be painful. Like viral conjunctivitis, it usually affects only one eye but may spread easily to the other eye.Irritant or toxic conjunctivitis is irritable or painful. Discharge and itch are usually absent. This is the only group in which severe pain may occur.Signs The patient should be examined in a well lit room. Injection (redness) of the conjunctiva on one or both eyes should be apparent, but may be quite mild. Except in obvious pyogenic or toxic/chemical conjunctivitis, a slit lamp (biomicroscope) is needed to have any confidence in the diagnosis. Examination of the tarsal conjunctiva is usually more diagnostic than the bulbar conjunctiva.Allergic conjunctivitis shows pale watery swelling or oedema of the conjunctiva and sometimes the whole eyelid, often with a ropy, non-purulent mucoid discharge. There is variable redness.Viral conjunctivitis, commonly known as 'pink eye', shows a fine diffuse pinkness of the conjunctiva which is easily mistaken for the 'ciliary injection' of iritis, but there are usually corroborative signs on biomicroscopy, particularly numerous lymphoid follicles on the tarsal conjunctiva, and sometimes a punctate keratitis.Pyogenic bacterial conjunctivitis shows an opaque purulent discharge, a very red eye, and on biomicroscopy there are numerous white cells and desquamated epithelial cells seen in the 'tear gutter' along the lid margin. The tarsal conjunctiva is a velvety red and not particularly follicular. Non-pyogenic infections can show just mild injection and be difficult to diagnose. Scarring of the tarsal conjunctiva is occasionally seen in chronic infections, especially in trachoma.Irritant or toxic conjunctivitis show primarily marked redness. If due to splash injury, it is often present only in the lower conjunctival sac. With some chemicals — above all with caustic alkalis such as sodium hydroxide — there may be necrosis of the conjunctiva with a deceptively white eye due to vascular closure, followed by sloughing of the dead epithelium. This is likely to be associated with slit-lamp evidence of anterior uveitis.Differential diagnosis Note that the symptoms and signs are relatively non-specific in conjunctivitis. Even after biomicrosopy, laboratory tests are often necessary if proof of aetiology is required.Prominent itch and pale watery swelling (edema) of the conjunctiva or eyelids suggests allergy.A purulent discharge strongly suggests bacterial cause, unless there is known exposure to toxins. Infection with Neiserria gonorrhea should be suspected if the discharge is particularly thick and copious.A diffuse, less 'injected' conjunctivitis (looking pink rather than red) suggests a viral cause, especially if numerous follicles are present on the lower tarsal conjunctiva on biomicroscopy.Scarring of the tarsal conjunctiva suggests trachoma, especially if seen in endemic areas, if the scarring is linear (von Arlt's line), or if there is also corneal vascularisation.Clinical tests for lagophthalmos, dry eye (Schirmer test) and unstable tear film may help distinguish the various types of dry eye.Other symptoms including pain, blurring of vision and photophobia should not be prominent in conjunctivitis. Fluctuating blurring is common, due to tearing and mucoid discharge. Mild photophobia is common. However, if any of these symptoms are prominent, it is important to exclude other diseases such as glaucoma, uveitis, keratitis and even meningitis or carotico-cavernous fistula.InvestigationsThese are done infrequently because most cases of conjunctivitis are treated empirically and (eventually) successfully, but often only after running the gamut of the common possibilities.Swabs for bacterial culture are necessary if the history & signs suggest bacterial conjunctivitis, but there is no response to topical antibiotics. Research studies indicate that many bacteria implicated in low-grade conjunctivitis are not detected by the usual culture methods of medical microbiology labs, so negative results are common. Viral culture may be appropriate in epidemic case clusters. Conjunctival scrapes for cytology can be useful in detecting chlamydial and fungal infections, allergy and dysplasia, but are rarely done because of the cost and the general lack of laboratory staff experienced in handling ocular specimens. Conjunctival incisional biopsy is occasionally done when granulomatous diseases (eg, sarcoidosis) or dysplasia are suspected.Treatment Conjunctivitis sometimes requires medical attention. The appropriate treatment depends on the cause of the problem. For the allergic type, cool compresses and artificial tears sometimes relieve discomfort in mild cases. In more severe cases, non-steroidal anti-inflammatory medications and antihistamines may be prescribed. Some patients with persistent allergic conjunctivitis may also require topical steroid drops. Bacterial conjunctivitis is usually treated with antibiotic eye drops or ointments that cover a broad range of bacteria.There is no cure for viral conjunctivitis. However, the symptoms can be relieved with cool compresses and artificial tears. For the worst cases, topical steroid drops may be prescribed to reduce the discomfort from inflammation. Viral conjunctivitis usually resolves within 3 weeks.Conjunctivitis due to burns, toxic and chemical require careful wash-out with saline, especially beneath the lids, and may require topical steroids. The more acute chemical injuries are medical emergencies, particularly alkali burns, which can lead to severe scarring, intraocular damage or even loss of the eye. Fortunately such injuries are uncommon, but the severity of the injury is often not recognised by the doctor or health worker initiating treatment.Glaucoma is an eye disease that is defined as a characteristic optic neuropathy, or disease of the optic nerve. Raised intraocular pressure is a significant risk factor for developing glaucoma. There is no set threshold for intraocular pressure that causes glaucoma — while one person may develop nerve damage at a relatively low pressure, another person may have high eye pressures for years and yet never develop damage. Untreated glaucoma leads to permanent damage of the optic disc of the retina and resultant visual field loss, which can progress to blindness.Contents 1 Types 2 Risk factors and diagnosis3 Treatment3.1 Drugs3.2 Surgery 4 Complications5 Major Studies Types The most common type, open angle glaucoma, frequently has no symptoms and has been nicknamed "the thief of sight". It is probably caused by a relative obstruction on the outflow of aqueous humour from the eye. Aqueous humour is produced by the ciliary body of the eye, and then flows through the pupil and into the anterior chamber. The trabecular meshwork then drains the humour to Schlemm's canal, and ultimately to the venous system. All eyes have some intraocular pressure, which is caused by some resistance to the flow of aqueous through the trabeculum and Schlemm's canal. If the intraocular pressure is too high, (>21.5 mm Hg), the pressure exerted on the walls of the eye result in compression of the ocular structures. Another type, acute angle-closure glaucoma, is characterized by an acute rise in the intraocular pressure. This occurs in susceptible eyes when the pupil dilates and blocks the flow of fluid through it, leading to the peripheral iris blocking the trabecular meshwork. Acute angle-closure glaucoma can cause pain and reduced visual acuity (blurred vision), and may lead to irreversible visual loss within a short time. This is an ocular emergency requiring immediate treatment. Many people with glaucoma experience halos around bright lights as well as the loss of sight characterized by the disease.Risk factors and diagnosis Normal vision. Courtesy NIH National Eye Institute The same view with advanced vision loss from glaucoma.People with a family history of glaucoma have about a six percent chance of developing glaucoma. Diabetics and Blacks are more prone to open angle glaucoma, and Asians are more prone to develop angle-closure glaucoma. Ideally, everyone over the age of thirty-five should be checked for glaucoma, with the frequency of the checkups increasing with age. Half the people who have glaucoma do not know that they have it. A number of studies suggest that there is a correlative, not necessarily causal, relationship between glaucoma and systemic hypertension (i.e. high blood pressure).Screening for glaucoma is usually performed as part of a standard eye examination performed by an ophthalmologist or optometrist. Testing for glaucoma should include measurement of the intraocular pressure, as well as examination of the optic nerve to look for any damage to it. If there is any suspicion of damage to the optic nerve, a formal visual field test should be performed. Scanning laser ophthalmoscopy may also be performed.Treatment Although intraocular pressure is only one of the causes of glaucoma, at the current time lowering it is the mainstay of glaucoma treatment.Drugs High intraocular pressure can be treated with eye drops that lower the eye pressure. There are several different classes of medications to treat glaucoma. There are several different medications in each class. These drugs tend to be cholinomimetics. Most common are beta blockers, such as timolol. Other drugs are cholinesterase inhibitors such as physostigmine. Marijuana has been shown to lower the intraocular pressure in some eyes in a few studies.The possible neuroprotective effects of various topical and systemic medications are also being investigated.Surgery(See Eye surgery)Both laser and conventional surgeries are performed to treat glaucoma. Laser trabeculoplasty may be used to treat open angle glaucoma. An argon or Nd:YAG laser spot is aimed at the trabecular meshwork to stimulate opening of the mesh to allow more outflow of aqueous fluid. Laser peripheral iridectomy may be used in patients susceptible to angle closure glaucoma. In it, the laser is aimed at the iris to make an opening in it. This allows a new channel for fluid to flow when the usual channel through the dilated pupil is blocked.The most common conventional surgery performed for glaucoma is the trabeculectomy. Here, a partial thickness flap is made in the scleral wall of the eye, and a window opening made under the flap to remove a portion of the trabecular meshwork. The scleral flap is then sutured loosely back in place. This allows fluid to flow out of the eye through this opening, resulting in lowered intraocular pressure.There are also several different small tubes that are inserted into the anterior chamber of the eye and out underneath the conjunctiva to allow flow of fluid out of the eye.Complications While glaucoma may or may not have distinct symptoms, an almost inevitable complication of glaucoma is vision loss. Visual loss from glaucoma first affects peripheral vision. Early vision loss is subtle, and is not noticed by the patient. Moderate to severe vision loss may be noticed by the patient by checking his peripheral vision thoroughly. This can be done by closing one eye and examining all four corners of the visual field for clarity and sharpness, then repeating with the other eye closed. All too often, the patient does not notice the loss of vision until he experiences "tunnel vision". If the disease is not treated, the visual field will become more and more narrow, obscuring central vision, and finally progressing to blindness in the affected eye(s).Visual loss related to glaucoma is irreversible, but can be prevented or slowed by treatment. If you suspect you may have glaucoma or have any risk factors for it, an appointment with an optometrist or ophthalmologist is indicated.A cataract is any opacity which develops in the crystalline lens of the eye or in its envelope. Cataracts form for a variety of reasons, including infrared and microwave exposure, secondary effects of diseases such as diabetes, or simply due to advanced age; they are usually a result of denaturation of lens proteins. Genetic factors are often a cause of congenital cataracts and may also play a role in predisposing someone to cataracts. Some cataract formation is to be expected in any person over the age of 70. Fully half of all people between the ages of 65 and 74 and about 70% of those over 75 have some cataract formation. Cataracts may also be produced by eye injury or physical trauma.Cataracts may be partial or complete, stationary or progressive, hard or soft. An early technique to remove cataracts was couching, which involved using a thin needle to remove the clouding. This technique is known to have existed in Roman times and continued to be used throughout the Middle Ages and continues to be used in underprivilleged "Third world" countries today.The most effective and common treatment for is cataract surgery to remove the cloudy lens. There are two types of surgery that can be used to remove cataracts, extra-capsular and intra-capsular surgery. Extra-capsular surgery consists of removing the lens but leaving the back half of the lens capsule intact. High frequency sound waves (phacoemulsification) are sometimes used to break up the lens before extraction. Intra-capsular surgery involves removing the entire lens of the eye, including the lens capsule, but it is rarely performed in modern practice. The lens is then replaced with a plastic lens (an intraocular lens implant) which remains permanently in the eye.Cataract operations are mostly performed under a local anaesthetic and the patient will be allowed to go home the same day. Complications after cataract surgery are uncommon. Many people (up to 50%) can develop a posterior capsular opacification after initial cataract surgery. This is a thickening and clouding of the lens capsule (which was left behind when the cataract was removed) and it can be easily corrected using a laser to make holes in the capsule for the person to see through. Retinal detachment is an uncommon complication of cataract surgery.Previously, polymethylmethacrylate was used as the lens material. Advances have brought about the use of silicone acrylate which is a soft material. This allows the lens to be folded and injected into the eye through a smaller incision. Acrylic lenses can also be used with small incisions and are a better choice in people who have a history of uveitis or are at high risk of retinal detachment. Acrylic is not always an ideal choice due to it's added expense.Macular degeneration is a medical condition where the light sensing cells in the macula malfunction and over time cease to work. It is the main cause of central vision loss in the USA blindness today for those over the age of fifty (Am.Acad.Ophthalmol.). There are two basic types of the disease: Standard Macular Degeneration (MD) and Age Related Macular Degeneration (ARMD). The main cause of macular degeneration is old age and thus age related macular degeneration is the most common form of the condition. However macular degeneration that is not age related is most commonly caused by disease or a heredity illness or condition. These forms are sometimes called Juvenile macular degeneration. In macular degeneration the final form results in complete blindness in the central part of the patient's vision.Content 1 Types of Degeneration 2 Typical Symptoms 3 Illnesses and Conditions that Cause Macular Degeneration 4 Research on Prevention of AMD Types of Degeneration Eighty five to ninety percent of all macular degeneration is categorized as "dry" macular degeneration where fatty tissue will slowly build up behind the retina. Ten to fifteen percent of cases are not, however, resulting from the build up of fatty tissue; these cases are called "wet" macular degeneration due to the leakage of blood and other fluid from behind the retina into the eye. If wet macular degeneration continues without treatment it will completely destroy the macula. Medical, photodynamic, laser photocoagulation and laser treatment of wet macular degeneration are available. The success of treatment and vision preservation is facilitated by arly ww.macular-degenerationThis is contemplated by home monitoring by the patients using a grid pattern called Amsler Grid test (Home Amsler Color Test (http://www.amsler.cc)). The test that is a black and white pattern to be viewed misses majority of defects ( references at www.ixm.us ) caused by the progression and therefore a more sensitive blue on yellow test pattern has recently been introduced.Typical Symptoms A grid of straight lines appears wavy and parts of the grid appear blank.Visual acuity drastically decreasing (two levels or more) ex: 20/20 to 20/80.Holes visible in fundus photographs.Trouble discerning colors; specifically dark ones from dark ones and light ones from light ones.Illnesses and Conditions that Cause Macular Degeneration Best's Disease Genetic Defects Stargardt's Disease Sorsby's DiseaseResearch on Prevention of AMD Recent studies suggest that Statins, a family of drugs used for reducing cholesterol levels, may be effective in prevention of AMD, and in slowing its progression.In adult humans the entire retina is 72% of a sphere about 22 mm in diameter. At the centre of the retina attaches the optic nerve. This spot is known as the blind spot as it lacks photoreceptors. It appears as an oval white area of 3 mm2. Temporal (in the direction of the temples) to this disc is the macula. At its center is the fovea, a pit that is most sensitive to light and is responsible for our sharp central vision. Around the fovea extends the central retina for about 6mm and then the peripheral retina. The edge of the retina is defined by the ora serrata. The length from one ora to the other (or macula), the most sensitive area along the horizontal meridian is about 3.2 mm.Retina's simplified axial organisation. The retina is a stack of several neuronal layers. Light is concentrated from the eye and passes across these layers (from left to right) to hit the photoreceptors (right layer). This elicits chemical transformation mediating a propagation of signal to the bipolar and horizontal cells (middle yellow layer). The signal is then propagated to the amacrine and ganglion cells. These neurons ultimately may produce action potentials on their axons. This spatiotemporal pattern of spikes determines the raw input from the eyes to the brain. (Modified from a drawing by Ramón y Cajal.)In section the retina is no more than 0.5 mm thick. It has five layers, three of nerve cells and two of synapses. The optic nerve carries the ganglion cell axons to the brain and the blood vessels that open into the retina. Perhaps as a product of evolution, the ganglion cells lie innermost in the retina while the photoreceptive cells lie outermost. Because of this light must first pass through the thickness of the retina before reaching the rods and cones. However it does not pass through the epithelium or the choroid (both of which are opaque).The white blood cells in the capillaries in front of the photoreceptors can be perceived as tiny bright moving dots when looking into blue light. This is known as the blue field entoptic phenomenon (or Scheerer's phenomenon).Between the ganglion cell layer and the rods and cones there are two layers of neuropils where synaptic contacts are made. The neuropil layers are the outer plexiform layer and the inner plexiform layer. In the outer the rod and cones connect to the vertically running bipolar cells and the horizontally oriented horizontal cells connect to ganglion cells.The central retina is cone-dominated and the peripheral retina is rod-dominated. In total there are about six million cones and a hundred and twenty-five million rods. At the centre of the macula is the foveal pit where the cones are smallest and in a hexagonal mosaic, the most efficient and highest density. Below the pit the other retina layers are displaced, before building up along the foveal slope until the rim of the fovea or parafovea which is the thickest portion of the retina. The macula has a yellow pigmentation from screening pigments and is known to ophthalmologists as the macula lutea.Operation of human retina An image is produced by the "patterned excitation" of the retinal receptors, the cones and rods. The excitation is processed by the neuronal system and various parts of the brain working in parallel to form a representation of the external environment in the brain.The cones respond to bright light and mediate high-resolution vison and colour vision. The rods respond to dim light and mediate lower-resolution, black-and-white, night vision. It is a lack of cones sensitive to red, blue, or green light that causes individuals to have deficiencies in colour vision or various kinds of colour blindness. Humans and old world monkeys have three different types of cones (trichromatic vision) while other mammals lack cones with red sensitive pigment and therefore have poorer (dichromatic) colour vision. When light falls on a receptor it sends a proportional response synaptically to bipolar cells which in turn signal the retinal ganglion cells. The receptors are also 'cross-linked' by horizontal cells and amacrine cells, which modify the synaptic signal before the ganglion cells. Rod and cone signals are intermixed and combine, although rods are mostly active in very poorly lit conditions and saturate in broad daylight, while cones are not sensitive enough to work at very low light levels.Despite all being nerve cells only the retinal ganglion cells and few amacrine cells create action potentials. In the photoreceptors exposure to light hyperpolarizes the membrane in a series of graded shifts. The outer cell segment contains a photopigment and the process leads to a change in levels of cyclic GMP, altering the sodium conductance of the membrane. The amount of neurotransmitter released is reduced in bright light and increases as light levels fall. The actual photopigment is bleached away in bright light and only replaced as a chemical process, so in a transition from bright light to darkness the eye can take up to thirty minutes to reach full sensitivity (see dark adaptation).In the retinal ganglion cells there are two types of response, depending on the receptive field of the cell. The receptive fields of retinal ganglion cells comprise a central approximately circular area, where light has one effect on the firing of the cell, and an annular surround, where light has the opposite effect on the firing of the cell. One response, from on cells, is to increase the rate of firing to increases in light intensity in the centre of the receptive field. The other response, from off cells, is to decrease the rate of firing to increases in light intensity in the centre of the receptive field. Beyond this simple difference ganglion cells are also differentiated by chromatic sensitivity and the type of spatial summation. With spatial summation cells showing linear summation are termed X cells (also called "P", "parvocellular" or "midget" ganglion cells), and those showing non-linear summation are Y cells (also called "magnocellular, "M", or "parasol" retinal ganglion cells).In the transfer of signal to the brain, the visual pathway, the retina is vertically divided in two, a temporal half and a nasal half. The axons from the nasal half cross the brain at the optic chiasma to join with axons from the temporal half of the other eye before passing into the lateral geniculate body.Although there are more than 130 million retinal receptors, there are only approximately 1.2 million fibres (axons) in the optic nerve so a large amount of pre-processing is performed within the retina. The fovea produces the most accurate information. Despite occupying about 0.01% of the visual field (less than 2° of visual angle), about 10% of axons in the optic nerve are devoted to the fovea. The resolution limit of the fovea has been determined at around 104 points. The information capacity is estimated at 5 x 105 bits per second (for more information on bits, see information theory) without colour or around 6 x 105 bits per second including colour.Diseases, diagnosis and treatment Using an ophthalmoscope an ophthalmologist can see the retina of an eye to determine its health. Recently, adaptive optics have been used to image individual rods and cones in the living human retina.The upcoming technology, which is recently becoming widespreadly available is Optical Coherence Tomography (OCT). This non-invasive technique allows to obtain a 3D volumetric or high resolution cross-sectional tomogram of the retinal fine structure histologic-quality.OCT scan of a retina at 800nm with an axial resolution of 3µmRetinitis pigmentosa is a genetic disease that affects the retina and causes the loss of peripheral vision.Macular degeneration describes a group of diseases characterized by loss of central vision because of death of the cells in the macula.In retinal separation, the retina detaches from the back of the eyeball. Ignipuncture is one treatment method.Both hypertension and diabetes mellitus can cause damage to the tiny blood vessels that supply the retina, leading to hypertensive retinopathy and diabetic retinopathy.Retinoblastoma is a cancer of the retina.transplantation of retinas has been attempted, but without much success.At MIT and the University of New South Wales, an "artificial retina" is under development: an implant which will bypass the photoreceptors of the retina and stimulate the attached nerve cells directly, with signals from a digital camera.Difference between vertebrate and cephalopod retinas As described above, the vertebrate retina is inverted in the sense that the light sensing cells sit at the back side of the retina, so that light has to pass through a layer of neurons before it reaches the photoreceptors. By contrast, the cephalopod retina is everted: the photoreceptors are located at the front side of the retina, with processing neurons behind them. Because of this, cephalopods don't have a blind spot.The cephalopod retina does not originate as an outgrowth of the brain, as the vertebrate one does. This shows that vertebrate and cephalopod eyes are not homologous but have evolved separately The cornea is the curved,transparent layer that covers the front part of the eye and protects its inner structures. Together with the lens, the cornea refracts light and consequently helps the eye to focus. The cornea gives a larger contribution to the total refraction than the lens, but whereas the curvature of the lens can be adjusted to "tune" the focus, the curvature of the cornea is fixed. The cornea has sensitive nerve endings; touch of the cornea causes an involuntary reflex to close the eyelid. Because transparency is of prime importance, the cornea does not have blood vessels; it receives nutrients via diffusion from the tear fluid at the outside and the aqueous humour at the inside. In humans, the cornea has a diameter of about 12 mm and a thickness of 0.5 - 0.7 mm in the center and 1.0 - 1.2 mm at the periphery.Medical terms related to the cornea often start with "kerat-".Contents 1 Layers of the cornea Surgical procedures involving the cornea 3 Non-Surgical procedures involving the cornea layers of the cornea The cornea consists of five layers. Here they are listed from the outside to the inside:Corneal epithelium: a thin epithelial layer of fast-growing and easily regenerated cells. Tears keep this layer moist.Anterior limiting membrane (also Bowman's membrane): a tough layer that protects the corneal stroma. It consists of irregularly arranged collagen fibers.Corneal stroma (also substantia propria); a thick, transparent middle layer responsible for most of the focusing that the cornea performs. It consists of regularly arranged collagen fibers along with (few) fibroblasts. If the stroma is damaged, for example by injury or infection, it can lose its transparency, causing vision problems.Posterior limiting membrane (also Descemet's membrane): a thin acellular layer that serves as the modified basement membrane of the corneal endothelium.Corneal endothelium: a simple squamous or low cuboidal epithelium, an inner lining acting as a barrier to prevent water inside the eyeball from moving into and hydrating the cornea, which would lead to blurred vision. (The term endothelium is a misnomer here. The corneal endothelium is bathed by aqueous humour, not by blood or lymph, and has a very different origin, function and appearance from vascular endothelia.The cornea is composed mostly of dense connective tissue, similar to the surrounding sclera. However, the collagen fibers are arranged in a parallel pattern, allowing light waves to constructively interfere, allowing the light to pass through relatively uninhibited.Surgical procedures involving the cornea Various refractive eye surgery techniques change the shape of the cornea in order to reduce the need for glasses or otherwise improve the refractive state of the eye. In the techniques used today, parts of the cornea are removed with lasers.If the corneal stroma has developed opaque patches known as leukomas, a cornea of a deceased donor can be transplanted. Because there are few blood vessels in the cornea, there are also few problems with rejection of the new cornea.There are also synthetic corneas in development. Most are merely plastic inserts, but there are also some made of plastics that encourage the eye tissue to grow into the synthetic cornea making it a full replacement.
Diseases and Disorders Links pertaining to Eye Diseases Alert! Patients and laypersons looking for guidance among the target sources of this collection of links are strongly advised to review the information retrieved with their professional health care provider Start Page Contents: Acute Zonal Occult Outer Retinopathy (not on MeSH) Adie Syndrome Adie Syndrome Albinism Ocular Amaurosis Fugax Amblyopia Aniridia Aniridia Aniridia Anisocoria Anophthalmos Aphakia Astigmatism Blepharitis Blepharoptosis Blepharospasm Blindness Cataract Chalazion Chorioretinitis Chorioretinitis Chorioretinitis Choroideremia Choroideremia Coloboma Color Vision Defects Conjunctival Diseases Conjunctivitis Corneal Diseases Corneal Dystrophies (not on MeSH) Corneal Edema Corneal Ulcer Corneal Ulcer Diabetic Retinopathy Diplopia Distichiasis (not on MeSH) Dry Eye Syndromes Duane Retraction Syndrome Duane Retraction Syndrome Ectropion Entropion Esotropia Exfoliation Syndrome Exotropia Eye Abnormalities Eye Diseases Eye Hemorrhage Eye Neoplasms Eyelid Diseases Floaters (not on MeSH) General Fibrosis Syndrome (not on MeSH) Glaucoma Gyrate Atrophy Gyrate Atrophy Hemianopsia Hermanski Pudlak Syndrome Hordeolum Hordeolum Horner Syndrome Hyperopia Hyphema Iritis Iritis Kearns Sayer Syndrome Kearns Sayer Syndrome Keratitis Keratoconus Lacrimal Apparatus Diseases Lacrimal Duct Obstruction Lens Diseases Macular Degeneration Microphthalmos Myopia Nystagmus Pathologic Ocular Motility Disorders Oculomotor Nerve Diseases Ophthalmoplegia Optic Atrophies Hereditary Optic Atrophies Hereditary Optic Nerve Diseases Optic Neuritis Optic Neuropathy Ischemic Orbital Cellulitis (not on MeSH) Papilledema Peter's Anomaly (not on MeSH) Presbyopia Pterygium Pupil Disorders Refractive Errors Retinal Detachment Retinal Diseases Retinal Vein Occlusion Retinitis Pigmentosa Retinitis Pigmentosa Retinopathy of Prematurity Retinoschisis Scleritis Scotoma Strabismus Thygeson's Superficial Punctate Keratitis (not on MeSH) Trachoma Trachoma Trachoma Uveitis White Dot Syndrome (not on MeSH) Vision Disorders VITREOUS DISORDERS (not on MeSH) Eye Diseases Anatomy Physiology and Pathology of the Human Eye [TM Montgomery] Physical Structures of the Eye [text only; L Hahn] U of Pennsylvania (US) Colored Eyes TipsOfAllSorts About the 'Blind Spot' Actually: The Main Lens of Your Eye Is Not Inside The Eye Simulations of certain eye problems Ohio LIONS Eye Research Foundation Distance Vision Test Perrot Optic (CH) About Visual Acuity [TM Montgomery] and the typical Visual Acuity Test ADAM via MedlinePlus The Eye Exam [C Goldberg] School of Medicine UCSD (US) Eye examination Indiana University (US) School of Optometry and Dr Riley's Diagnostic Procedures Indiana University (US) Ophthalmology information eMedicine Eye Diseases and Disorders an illustrated encyclopedia StLukes Eye An Ocular Pathology Review [RC Eagle] Wills Eye Hospitale Red Eyes: The Good the Bad and the Ugly [DT Adamczyk 1999] Optometry Today (UK) Managing the Red Eye Well Close Square Surgery (UK) About Itchy Eyes Kellogg Eye Center Symptoms of damage to the optic chiasm Yale School of Medicine Ocular Symptoms and Diagnoses Richmond Eye Associates About some Selected Anomalies and Diseases of the Eye Texas School for the Blind (US) Testing Babies' Vision ICH (UK) About Children's Vision AOA Glasses for Children AAPOS Pediatric Vision Screening for the Family Physician [P Broderick] Am Family Phys Sep '98 About LEA symbols Am Assoc for Pediatric Ophthalmology & Strabismus including a Public Resource Library Handbook of Ocular Disease Management '98 Review of Optometry Online OPHTHALMIC hyperguide [free registration required] Success in MRCOphth [CN Chua] including the Oxford Eye Page and an Ophthalmic Kew Garden (UK) EyeAtlas Oculisti Online Atlas of Ophthalmology Online Journal of Ophthalmology Ophthalmic Pathology Archive JA Moran Eye Center Utah (US) SNOF Syndicat National des Ophtalmologistes de France including Maladies des yeux [in French] American Academy of Ophthalmology Clinical Cases (Grand Rounds) at DJO/Harvard Educational cases for diagnosis [image + Q/A] Umeå Univ/Dept of Ophthalmology (SE) Clinical section Richmond Eye Associates Digital Grand Rounds from OptComcom/CIBA Inc Lernprogramm für Augenfachärzte und Medizinstudenten [O Findl; in German and English] Vienna (AT) Der Augenfundus [C Daetwyler; in German] (CH) Eye Plastics Surgery EyePlastics LLC Abstracts and FAQs EyeCare Connection A Philosophy Of Blindness [K Jernigan] Blindness Related Resources on the Web & Beyond including a List of European Organizations & Foundations Oedipal Enterprises The US National Federation of the Blind Blind Childrens Center (US) Living with vision loss A handbook for caregivers Canadian Nat'l Inst for the Blind Links to Mobility & Braille Resources [R Marriage] Visual Prosthesis for the Totally Blind Seeing Eye Information Center (dog guide school) (US) About Leader Dogs GuideDogsOrgUK About Enucleation: Removal of an Eye Wills Eye Hospital (US) Enucleation information EyeCancer Network The Artificial Eye Information & Patient Support Page LostEyecom Movements On Line (about artificial eyes/implants) and Artificial Eyes: Surgical Techniques Bio eye Orbital Implants International Eye Foundation Vision Science [research; A Watson] NASA (US) 3 D Vision [R Cooper] About Rhodopsin [G Schertler] Lab Mol Biology MRC Centre/Cambridge (UK) How Photons Start Vision [D Baylor] PNAS '96 The NEIBank [a database of genes/proteins expressed in the eye/visual system] NEI/NIH (US) Useful Numbers in Vision Science: A Preliminary List [B Wandell] (US) Test Your Knowledge The Ophthalmic Photographers' Society Inc (US) Visionary: A Dictionary for the Study of Vision Sensation and Perception PsychScholar Hanover College (US) Glossary of Ophthalmologic Terms [L Bickford] The EyeCare Connection (US) A List of US Eye Health Organizations NEI/NIH (US) The Joy of Visual Perception [P Kaiser] York Univ (CA) The Art of Vision [M Dubin] Univ of Colorado (US) InterNet Journal of Ophthalmology [no charge] (IT) Molecular Vision [journal] (US) Review of Ophthalmology [journal] Ophthalmology Review Journal Conjunctival Diseases Notes about Diseases and Disorders of the Conjunctiva [K Reed] Conjunctival Disorders Merck Manual About Conjunctival Foreign Body [Buttravoli and Stair] NCEMI Removing a Foreign Object from Your Eye MedlinePlus/ADAM (US) Conjunctivitis Neonatal Conjunctivitis Adam via MedlinePlus About Pink Eye [D'Alessandro and Huth] Virtual Hosp Iowa Assessment of the Red Eye Canadian Ophthalmological Society Managing the Red Eye Well Close Square Surgery (UK) Conjunctivitis [Morrow and Abbot] Am Family Phys Feb '98 Allergic Conjunctivitis CIBA Vision Ocular Allergy [EK Akpek] MEEI/Harvard (US) A case of Giant Papillary Conjunctivitis Paragon Vision Sci About Giant Papillary Conjunctivitis [B Weissman] e Medicine Trachoma Helen Keller Int'l Trachoma Task Force Int'l Trachoma Alliance WHO (CH) WHO Treatment Recommendations via Univ of Cape Town/Groote Schuur Hosp (ZA) VITREOUS DISORDERS (not on MeSH) About Vitreous Detachment Richmond Eye Assoc About Vitreous Detachment NEI/NIH (US) About Vitrectomy StLukes Eye Institute (US) and some photos [WD Leahy Jr] Floaters (not on MeSH) Spots and Floaters AOA (US) About Eye Floaters Flashes and Floaters What you need to know [Goldman and Polk] The Retina Center Floaters discussions at Med Help International Vitreous Opacities GPnotebook (UK) Laser Treatment of Eye Floaters [JR Karickhoff] (US) About Vitreous and Retinal Detachment New England Eye Center (US) The American Society of Retina Specialists (formely 'The Vitreous Society') About Hyaluronan and the Vitreous Humor [JE Scott] Some FAQs about Floaters and Surgery [scroll down a bit] Charles Retina Institute Pterygium Pterygium DJO/Harvard (US) About Pterygium Handbook of Ocular Disease Mgmt and an image EyeMac About Pterygium and Pinguecula North Shore Eye C (AU) Brief description of Pingueculae (yellowish spots of conjunctival tissue) Eye Care Saratoga (US) About Pingueculum Kellogg Eye Center (US) Corneal Diseases The Cornea and Corneal Diseases NEI/NIH (US) Corneal Disease Management Review of Optometry/Handbook Corneal Disorders Merck Manual Managing the Red Eye Well Close Square Surgery (UK) Corneal foreign body and Corneal abrasion [Buttravoli and Stair] NCEMI PKA Pediatric Keratoplasty Association (US) About Corneal Modification techniques AOA (US) About Corneal Graft Moorfields Eye Hosp London (UK) Ny hornhinna ger synen tillbaka [M Claesson] (in Swedish) CORPUS MEDICUM Corneal Edema About Bullous Keratopathy EyeMDLink Keratopathy Pseudophakic Bullous [Aquavella and Singer] eMedicine Keratitis Herpes Simplex Keratitis Rev of Optometry/Handbook On Fungal Keratitis [T Romero Rangel] and Recurrent Herpes Simplex Keratitis in Penetrating Keratoplasty [N Tesavibul '97] MEEI/Harvard Peripheral Ulcerative Keratitis PUK [T Ekong] MEEI/Harvard Keratitis: A Quick and Accurate Diagnosis [LJ Catania] Rev of Optometry Nov 2001 Best Weapon Against Bacterial Keratitis? [JA McGreal] Review of Optometry/Educ Center 1999 UV Keratitis or Snowblindness [R Brozen] e Medicine Thygeson's Superficial Punctate Keratitis (not on MeSH) About Thygeson's Superficial Punctate Keratitis Univ of Iowa/OPHTH (US) Thygeson's Superficial Punctate Keratopathy Review of Optometry Corneal Ulcer Corneal Abrasion vs Corneal Ulcer [S Awwad] EyewebOrg Mooren's Ulcer [QD Nguyen] MEEI/Harvard (US) Cogan's Dystrophy (Map Dot Fingerprint Dystrophy) StLukesEyecom Dystrophy Map Dot Fingerprint [D Verdier] eMedicine Peter's Anomaly (not on MeSH) Peter's Anomaly Support Group Corneal Dystrophies (not on MeSH) Corneal Dystrophy factsheet RNIB (UK) Bietti's Crystalline Dystrophy NEI/NIH (US) About Fuchs' Endothelial Dystrophy Review of Optometry/Handbook Brief note on Fuchs' Endothelial Dystrophy Insight/Utah A question & answer about Fuchs' Syndrome The Eye Care Forum/MedHelp Genetic aspects of Corneal Dystrophy Juvenile Epithelial of Meesmann OMIM (US) Keratoconus Keratoconus Indiana University (US) and an image EyeMac About Keratoconus [R Pineda] Harvard Med School (US) Keratoconus: Diagnosis and Management [Burger et al] Pacific Univ/College of Optometry US Nat'l Keratoconus Foundation Center for Keratoconus (US) What happens during a cornea transplantation? TransWeb Trachoma See another location Eye Abnormalities About Orbital Reconstruction The Craniofacial Surgery Book Erlanger Health System (US) Aniridia Brief note about Aniridia Nobel Foundation (SE) About Aniridia The Aniridia Network (UK) About the WAGR Syndrome Anirida ; AN1 OMIM Anophthalmos The Micro and Anophthalmic Childrens Society (UK) ICAN Families with Anophthalmia Children Anophthalmia Microphthalmia and Other Related Eye Disorders [Diann ?] About Franchesca (anophthalmia) Coloboma About Coloboma RNIB (UK) About Coloboma MACS (UK) Coloboma Texas School for the Blind (US) Microphthalmos The Micro and Anophthalmic Childrens Society (UK) Anophthalmia Microphthalmia and Other Related Eye Disorders [Diann ?] Eye Diseases Hereditary Albinism Albinism Ocular About Ocular Albinism NOAH Philadelphia (US) Ocular Albinism Ocular Albinism [review course; JM Weber] MarchOn Training Center NY (US) Bianca's Pages the [Knowlton] family Albinism Oculocutaneous Hermanski Pudlak Syndrome About Hermansky Pudlak Syndrome NOAH Philadelphia (US) Hermansky Pudlak Syndrome [summary; Krisp et al] Eur J Dermatol 11/4 2001 Hermansky Pudlak Syndrome Type 3 in Ashkenazi Jews and Other Non Puertorican Patients with Hypopigmentation and Platelet Storage Pool Deficiency [Huizing et al] Am J Hum Genet 69/2001 The Hermansky Pudlak Syndrome Network Inc via MedHelpOrg Aniridia See another location Choroideremia About Choroideremia OMIM (US) The Chroroideremia Research Foundation Inc General Fibrosis Syndrome (not on MeSH) About Congenital Fibrosis Syndrome U of Buffalo (US) Duane Retraction Syndrome About Duane Syndrome [A Verma] eMedicine Duane Syndrome Children's Hospital Boston (US) Gyrate Atrophy About Gyrate Atrophy NCBI/NIH (US) Optic Atrophies Hereditary About Optic Atrophy The Leber's Optic Neuropathy [J Leeder] (UK) Genetic aspects of Leber's Hereditary Optic Neuropathy [D Berro] On Leber's hereditary optic neuropathy [Kerrison and Newman] Clinical neuroscience 1997 Retinitis Pigmentosa Information about Retinitis Pigmentosa Foundation Fighting Blindness (US) Retina International including the Retina Int'l Newsletter About Retinitis Pigmentosa [de Beus and Small] eMedicine About Retinitis Pigmentosa [JD Reynolds] MedHelp (US) Retinitis Pigmentosa links [J Wenberg] Retinitis Pigmentosa Genetics GeneTests Die Deutsche Retinitis Pigmentosa Vereinigung (DE) Eye Hemorrhage A note about Subconjunctival Hemorrhage Ocular Trauma information Univ of Wisconsin (US) About Preventing Eye Injuries and Management of Orbital Fractures [B Biesman] New England Eye Center (US) About 38 year old man who was hit in the left eye with a pool cue [Lucarelli et al] DJO Eye Casualty information Oxford (UK) Subconjunctival hemorrhage [Buttravoli and Stair] NCEMI Injured Eye a self directed learning module Canadian Opthalmological Society Hyphema A case of painful red eye [Hemphill & Doe] EMBBS (US) Spontaneous microscopic hyphema and an image of Hyphema [L Edwards] (US) Eye Infections Corneal Ulcer See another location Eye Infections Bacterial Conjunctivitis Bacterial Trachoma See another location Hordeolum About Hordeolum and Sty [M Bessette] and Chalazion [S Santen] eMedicine Hordeolum and chalazion treatment The full gamut [L Skorin] Optometry Today Jun 2002 (UK) Eye Neoplasms Articles about Ocular Tumors Cancer Control Jul/Aug '98/Moffitt Cancer Center The Eye Cancer Network [P Finger; texts & images] Orbital Tumors ASOPRS Center for Ocular Oncology Washington Univ St Louis (US) About Ocular Lymphoma [J Yang] Ocular Immunology/Mass Eye & Ear Infirmary (US) See also under Retinoblastoma [links] KIB A Choroidal Melanoma tumor [image] Ohio State Univ About Choroidal Melanoma from the Collaborative Ocular Melanoma Study Wilmer Eye Institute/JHU (US) Briefly about Melanoma of the Eye Adam via MedlinePlus and an image (malignant melanoma) [NC White] About Intraocular Melanoma Cancergov Eyelid Skin Cancers ASOPRS Eyelid Diseases Eyelid Disorders: Diagnosis and Management [SR Carter] Am Family Phys Jun '98 A brief note about Eccrine cysts in the eyelids EBM Guidelines Duodecim (FI) Eye Plastics (oculoplastic surgery) About Blepharoplasty questions & comments [M Bermant] (US) Blepharitis About various forms of Blepharitiis American Optometric Association Brief note about Phlyctenulosis Perret Opticiens (CH) Blepharoptosis About Acquired and Congenital Ptosis ASOPRS Ptosis Classification and Eyelid Surgery for Ptosis Qs & As [M Bermant] (US) Double Elevator Palsy [Olitsky and Nelson] Strabismus Web Book Blepharospasm About Eyelid Spasms/Twitching Kellogg Eye Center Blepharospasm Pages BEBRF Blepharospasm and Botox EyePlastics Blepharospasm Benign Essential [SM Saulny] eMedicine Essential Blepharospasm and Hemifacial Spasm ASOPRS On the Side Effects of Botulinum Toxin Therapy Smith Kettlewell Inst (US) Distichiasis (not on MeSH) Distichiasis [S Rostami] eMedicine Chalazion About Styes and Chalazions [L Bickford] The EyeCare Connection (US) A Case of Chalazion MDChoice (US) Ectropion About Ectropion: "Eyelid Turning Out" and some more on Ectropion [M Bermant] (US) Cicatricial Ectropion and Paralytic Ectropion ASOPRS Entropion Entropion: "Eyelid Turning In" ASOPRS Transconjunctival Entropion Repair [SC Dresner '93] Trichiasis [RW Pelton] eMedicine Hordeolum See another location Lacrimal Apparatus Diseases Disorders of the Lacrimal System Merck Manual The Wet Eye: "Excessive Tearing" ASOPRS Excessive tearing in infancy and early childhood [EA Ballard] PostGradMed May '00 Dacryocystorhinostomy for Tearing EyeMDLink About Dacryocystorhinostomy (DCR) [SV Fernandes] eMedicine About Surgery for Lacrimal Disorders EyePlastics LLC Two illustrations of the lacrimal system Texas Ophthal Plast Surg (US) Dry Eye Syndromes Dry Eye Syndrome StLukes Eye (US) Dry Eye Syndromes and an image of the tear film layers Schepens Eye Research Institute About Restasis Aging Eye Times See also under Sjogren's Syndrome Lacrimal Duct Obstruction About Tear Duct Obstruction and Surgery KidsHealth About Pediatric Balloon Dacryoplasty LacriCATH/Quest Medical Inc Nasolacrimal Duct obstruction AAPOS Lens Diseases The histology and biology of the lens [MJ Stafford] Optometry Today Jan 2001 (UK) Notes about Diseases and Disorders of the Crystalline Lens [K Reed] Aphakia Brief Note about Aphakia On Aphakia [CN Chua] About Pediatric Aphakia [C Sindt] Children's Virtual Hospital The PHPV and Aphakia Support Pages Cataract About Cataract [brochure for people at risk] National Eye Institute (US) About Cataracts NEEC (US) Cataracts [Trudo and Stark] PostGradMed May 1998 American Soc of Cataract & Refractive Surgery and the J of Cataract & Refractive Surgery (US) What Can Go Wrong With Cataract Surgery? [Insinga and Quinn] Review of Optometry/Study Center Cataract Removal YourSurgery My experience with Cataract Surgery [a personal account ; J Ott(?)] Care of the Adult Patient with Cataract [Rouse et al 1999] AOA Ocular Hypertension Glaucoma Facts about Glaucoma NEI/NIH and about Types of Glaucoma Glaucoma Foundation (US) Glaucoma Network Glaucoma Assoc of N Y (US) The Glaucoma Research Foundation including a What's New section San Francisco (US) The Glaucoma Foundation NY (US) Illustration of Flow of Aqueous Humor AHAF Brief note about Closed Angle Glaucoma JA Moran Eye C/Univ of Utah (US) What is Angle Closure Glaucoma? Wills Eye Hospital Subacute glaucoma masquerading as migraine [Nesher et al] PostGradMed Feb 2003 About Open Angle Glaucoma and Acute Narrow Angle Glaucoma VisionRx Some Glaucoma Related Articles State University NY Buffalo (US) Glaucoma and Intramedical Pressure [raych? 1993] A chat with Dr Rick Wilson on Normal Tension Glaucoma and the Family Connection Wills Glausoma About Glaucoma Medications and their Side Effects GANY (US) About Pilocarpine ADAM via MedlinePlus Ocular Motility Disorders American Orthoptic Journal (US) The Engle Laboratory at Children's Hospital Boston (US) Clinical Examination of Ocular Motility Richmond Eye Associates (US) Dancing Eyes and Other Maladies of the Nervous System [J Hsiao] Yale Journal for Humanities in Medicine On (Saccadic Nystagmus/) Opsoclonus [TC Hain] See also under Paraneoplastic Syndromes Nervous System [links] Brown Syndrome [K Wright] e Medicine Brown Syndrome [Olitsky and Nelson] Buffalo (US) Duane Retraction Syndrome See another location Nystagmus Pathologic Some notes on Nystagmus [J Hamilton] The Berries The Understanding Nystagmus Royal College of Ophthalmologists (UK) Understanding Nystagmus [RL Windsor] Nystagmus Congenital/Infantile [DT Wheeler] eMedicine The American Nystagmus Network Common cases in Nystagmus [CN Chua] (UK) Understanding Nystagmus RNIB (UK) On Nystagmus subtypes etc and Saccade Tests [TC Hain] (US) About Alström's syndrome Alstrom Syndrome support group in the (UK) Oculomotor Nerve Diseases The Oculomotor Nerve [image] Gray's Anatomy 1918 About Third Nerve Palsy U of Birmingham (UK) Adie Syndrome Brief Note about Adie's (Tonic) Pupil not to be confused with Argyll Robertson Pupil JHU/School of Med (US) Ophthalmoplegia About Internuclear Ophthalmoplegia Handbook of Ocular Disease Mgmt About Chronic Progressive Externav Ophthalmoplegia [Schmuckler and Hampton] eMedicine Tolosa Hunt Syndrome [Taylor and Mankowski] eMedicine About Tolosa Hunt Syndrome eMEDMAN A case of Miller Fisher Syndrome Baylor College TX (US) Ophthalmoplegia Chronic Progressive External Kearns Sayer Syndrome About Kearns Sayre Syndrome OMIM (US) Kearns Sayre Syndrome "Plus": A Case Report [Foyaca Sibat and Ibanez Valde's] Internet J of Neurology 1/2 Strabismus American Association for Pediatric Ophthalmology and Strabismus and some General info about Strabismus A Strabismus Web Book [Olitsky and Nelson] Buffalo (US) The Pediatric and Adult Strabismus Resource at McGill Univ (CA) Strabismus a self directed learning module Canadian Opthalmological Society Angle of Deviation (Differentiating between Non Strabismus and Strabismus Disorders) [BB Rainey] Indiana Univ/Optometry George's Eyes (Strabismus surgery) [G Westlund] Esotropia About Accomodative Esotropia (eye turning inward) PedsEye (US) Exotropia About Exotropia (eye turning outward) PedsEye (US) Optic Nerve Diseases Optic Nerve Disorders Merck Manual Home Edition International Foundation for Optic Nerve Disease Optic Nerve Head Drusen Review of Optometry Online What a Nerve! Differentiating Congenital Anomalies of the Optic Disc [Kabat and Sowka] Pacific Univ College of Optometry Optic Atrophies Hereditary See another location Optic Neuritis On Optic Neuritis and MS Nat'l MS Society (US) Optic Neuritis (and MS) FireLady About Optic Neuritis and Multiple Sclerosis MayoClinic Optic Neuritis in Multiple Sclerosis [TJ Copeland Jr] A Review of Optic Neuritis [Graham and Rizzo] DJO/Harvard (US) About Papillitis SpEdEx Optic Neuropathy Ischemic Ischemic Optic Neuropathy IFOND About Anterior Ischemic Optic Neuropathy Univ of Iowa (US) On Surgery for nonarteritic anterior ischemic optic neuropathy Cochrane Review 2003 Papilledema Optic Disc Edema & Papilledema Review of Optometry Online About Papilledema [Giovanni and Chrousos] e Medicine Synopsis of Papilledema examination FP Notebook On Papilledema and Pseudo Papilledema [WF Hoyt] Univ of Utah Pupil Disorders Common pupillary cases [CN Chua] (UK) About Marcus Gunn Jaw winking Syndrome [SM Blaydon] eMedicine and an animated illustration [CN Chua] (UK) About the Argyll Robertson pupil [Dente and Gurwood] Optometry Today 10/1999 (UK) Argyll Robertson Pupil synopsis FPNoteBook About Leukocoria (white pupil cat's eye) Paediatric Ophthalmology Univ of Toronto (CA) A case of Leukocoria Indian Pediatrics Brief note about Leukocoria (white pupil) Univ of Maryland medicine Anisocoria About Anisocoria (Unequal Pupils) [W Zein] EyewebOrg Miosis Horner Syndrome About Horners Syndrome DrugInfoNet Horner's Syndrome Review of Optometry A Case of Unilateral Ptosis Headache (Horner's Syndrome) Richmond Eye Associates About Raeder's Paratrigeminal Syndrome [SH Schechter] eMedicine Tonic Pupil Adie Syndrome See another location Refractive Errors About Accomodation Indiana Univ/School of Optometry (US) Some FAQs about Contact Lenses Contact Lens Manufactures Assoc About Corneal Topography [P Kollbaum] School of Optometry Indiana Univ (US) About Contact Lenses HON (CH) and some some FAQs Contact Lens Council (US) Advantages and Disadvantages of Various Types of Contact Lenses AOA (US) Contact lens irritation contamination overuse [Buttravoli and Stair] NCEMI Removal of dislocated contact lens [Buttravoli and Stair] NCEMI On Contact Lens Associated Eye Infections Topics in Infect Dis Newsletter Jul 2001 (AU) Corneal Modifications for Improved Vision American Optometric Association Refractive Source (refractive surgery information) including a collection of Refractive Surgery Grand Rounds [B Chou] About Monovision St Lukes Eye and The Controversy over "Monovision" Lenses Aviation Medicine Jan 1998 A Letter by FDA on Lasers and Refractive Surgery July '97 How LASIK Surgery works Columbia Vision Correction About LASIK PRK LASEK Refractive Surgery The LASIK Institute and LASIK fundamentals and what can realistically be expected from having refractive surgery (US) Eye Surgery Education Council ASCRS (US) An How Lasers Work How Stuff Works Astigmatism About Astigmatism AOA (US) About Astigmatism St Lukes Eye (US) Windows based software for Astigmatism analysis (NA Alpins' method) Buzard Incisional Astigmatism Nomograms Buzard Eye Institute An Astigmatism Test Perret Optic (CH) Correct astigmatism with peripheral corneal relxing incisions after LASIK [M Lipner] EyeWorld Hyperopia Hyperopia TLC and briefly about treatment by LASIK Schulze Eye & Surgery C Care of the Patient with Hyperopia AOA Myopia About Myopia [L Bickford] The EyeCare Connection (US) Can We Conquer Myopia? [DO Mutti] Review of Optometry/Study Center The Neural Basis of Myopia [Raviola and Wiesel] On The Brain/Harvard Mahoney Neurosci Inst Letter '95 Myopia Prevention Home Page [a personal view by J Arthur] About High Degree Myopia (Pathological/Degenerative Myopia) RNIB (UK) Presbyopia AgingEye Times Aging Eye (CA) Examining the elderly population Strategies for the optometrist [L Weddell] Optometry Today Feb 2003 (UK) Refractive Error and Presbyopia Refractive Surgery Presbyopia CIBA Vision Presbyopia [J Rumsey] Nova SE Univ FL (US) Surgery for 'Short Arm Syndrome' [J Murphy] Review of Optometry Dec 2003 PresbyopiaOrg Varilux/Essilor Int'l Presbyopia surgically corrected with PMMA segments Marmer Med Eye C Atlanta (US) Retinal Diseases The Neural Organization of the Vertebrate Retina [Kolb et al] WebVision Utah (US) Retina neurons map (CA) Diseases of the Vitreous and Retina Review of Optometry Peripheral Retina Lecture Diagnostic Procedures [HD Riley] Indiana School of Optometry Retina Reference University of Pennsylvania (US) RetNet: Retinal Information Network including a current list of Genes Causing Retinal Diseases TX (US) Retina International The Retina Source com Retina France (FR) What's New in Science from the Foundation Fighting Blindness (US) About Optical Coherence Tomography New England Eye Center (US) The Boston Retinal Implant Project MIT (US) About some Inherited Retinal Disorders and Retinal Ischemic Diseases LKC Technologies Inc (US) About Vitrectomy StLukes Eye Surgery (US) Macular Pucker / Epithelial Membrane AQngeles Vision Clinic (US) About Macular Hole Macula Surgery Alabama (US) Developments in retinal cell transplants [Sharma et al] Dig J Ophthalmol 7(2) 2001 A case of Coat's Disease DJO Harvard (US) The Paradigm/Dicon Company Home Page (US) RETINA (journal of Retinal & Vitreous diseases) Diabetic Retinopathy Diabetic Retinopathy NEI (US) About Diabetic Retinopathy St Luke's Cataract & Laser Institute Diabetic Retinopathy DJO Harvard (US) European Association for the Study of Diabetic Eye Complications MedWeb Birmingham (UK) Retinal Degeneration Macular Degeneration An overview of some Diseases of the Macula (HK) Age Related Macular Degeneration Indiana University (US) About Age related Macular Degeneration [brochure for people at risk] National Eye Institute (US) Age related macular degeneration An overview [Mathews Mathews and Kelly] Optometry Today Feb 2003 (UK) Loss of Central Vision illustrated Retina International Illustrations of Macular Degeneration AHAF Macular Degeneration Help Center MD Partnership Macular Degeneration Network [PT Finger] NY (US) Juvenile Macular Degeneration Macular Degeneration Int'l Information about Age Related Macular Degeneration Stargardt Disease some more on Stargardt Disease MedStudents (BR) and about Best Disease (Vitelliform Macular Dystrophy type 2) Foundation Fighting Blindness (US) About Best's Disease RNIB (UK) About the Dry and Wet form of MD Wilmer Eye Inst/JHU The Amsler Test Augende (DE) The Macular Degeneration Foundation including a Blind Spot Amsler Grid test and a News Section Macular Degeneration Foundation Inc (US) What Is Fluorescein Angiography? St Lukes Eye (US) About Fluorescein Angiography Ophthalmic Photographers' Society Inc Brian's Eye Story (CA) On Macular Degeneration and Cataract Surgery St Luke's Eye and reference abstract PubMed Photodynamic Therapy Approved for the Wet Type of Age Related Macular Degeneration Oct '00 Univ of Washington/Ophthalmology (US) Antioxidant Vitamins and Zinc Reduce Risk of Vision Loss from Age Related Macular Degeneratio NIH News Oct 2001 (US) Retinitis Pigmentosa See another location Kearns Sayer Syndrome See another location Retinoschisis About Retinoschisis EyeMDLink Retinoschisis Kellogg Eye Center About Retinoschisis Juvenile [M K Song] and Retinoschisis Senile [Philpotts and Gounder] eMedicine The X linked Retinoschisis sequence variation database [JT den Dunnen] (NL) Retinal Detachment About Detached Retina Kellogg Eye Center What is Retinal Tear or Detachment? St Lukes Eye Retinal Detachment EyeSite (CA) About Vitrous and Retinal Detachment New England Eye Center (US) Retinal Vein Occlusion Brief note about Retinal Vessel Occlusion Adam via MedlinePlus About Central Retinal Vein Occlusion [SS Hayreh] U of Iowa/Ophth and Visual Sci Retinal Vein Occlusions Handbook of Ocular Disease Management Retinal Vein Occlusion Diagnosis and management [L Skorin Jr] Optometry Today Jan 2002 (UK) Retinal Vein Occlusion (Central and Branch) Angeles Vision Clinic (US) Retinal Vein Occlusion Guidelines Royal College of Ophthalmologists 2004 (UK) A 43 year old man with 3 days of blurry vision OS DJO Harvard (US) Retinal Vein Occlusions GoodHope Predicting Outcome in Central Retinal Vein Occlusion LKC Tech Branch Retinal Vein Occlusion [Wu and Mena] eMedicine A 73 year old healthy woman EBOLA Retinitis Chorioretinitis About Chorioretinitis [QV Nguyen] eMedicine Chorioretinitis in Congenital Toxoplasmosis [a few images included] Cytomegalovirus infections in AIDS patients AIDS Knowledge Base Acute Zonal Occult Outer Retinopathy (not on MeSH) About AZOOR Moorfields Eye Hospital (UK) AZOOR Support Group and Information Forum [L Upchurch] (UK) Retinopathy of Prematurity A Retinopathy of Prematurity Information Library [S Jane?] ROPARD: The Association for Retinopathy of Prematurity Michigan (US) Understanding Retinopathy of Prematurity [R and L Windsor] Low Vision Gateway Retinopathy of Prematurity [K Moss] TSBVI (US) Malina's story (ROP with complications) via GrowingStrong White Dot Syndrome (not on MeSH) White Dot Syndromes [Tewari and Eliott] eMedicine Multifocal Choroiditis and Panuveitis ( MCP ) [Pinar and Foster] MEEI/Harvard (US) Atlas de Coriorretinitis Multifocales [de Figueroa et al; in Spanish] Scleral Diseases Scleritis On Scleritis Merck Manual A 28 year old woman NetMedicine and some brief info about Episcleritis St Luke's Cataract & Laser Inst About Episcleritis Review of Optometry About Episcleritis [H Roy] eMedicine About Scleritis Review of Optometry and an image (Scleritis) via EyeMac Correspondence on SOS (Sands of the Sahara) Syndrome Buzard Eye Institute Uveal Diseases Choroid Diseases Choroideremia See another location Choroiditis Chorioretinitis See another location Gyrate Atrophy See another location Iris Diseases Aniridia See another location Exfoliation Syndrome Exfoliation syndrome: Clinical findings and Occurrence in [R Ritch] Pseudoexfoliation Glaucoma [ME Pons] eMedicine Brief note on Pseudoexfoliation Univ of Utah (US) Pseudoexfoliation Syndrome and Pseudoexfoliative Glaucoma Review of Optometry Iritis Managing the Red Eye Well Close Square Surgery (UK) The Iritis Organization (US) A brief note about Vossius Ring Univ of Wisconsin (US) Uveitis Uveitis Merck Manual Uveitis factsheet from RNIB (UK) About Uveitis and Immunology MEEI/Harvard (US) Differential diagnosis and management of uveitis [Kok and Lightman] Optometry Today Nov 2002 (UK) Uveitis When to investigate? Ophthalmic Network Research/Royal Coll of Ophthalmologists (UK) Juvenile Rheumatoid Arthritis associated Uveitis [M Samson] MEEI/Harvard (US) Pediatric Uveitis [S Foster] MEEI/Harvard (US) HLA B27 Associated Uveitis [NK Waheed] MEEI/Harvard (US) Intermediate Uveitis [V Pinar] MEEI/Harvard (US) Syphilitic Uveitis [M Samson] MEEI/Harvard (US) New Treatment May Improve Patient's Quality Of Life NIH Jun '99 Masquerade Syndromes [QD Nguyen] MEEI/Harvard (US) Notes on Posterior Uveitis [J Sowka] A Case of Endophthalmitis ACEP Hawaii Findings from the Endophthalmitis Vitrectomy Study [Oct '95] NLM (US) Iritis See another location Uveitis Posterior Choroiditis Chorioretinitis See another location Vision Disorders On evaluating Loss of Vision [Pathai and McNaught] StudentBMJ Nov 2002 On Sudden Painless Loss of Vision Canadian Ophthalmological Society Amblyopia Care of the Patient with Amblyopia [Rouse et al] AOA 1998 About Amblyopia / Lazy Eye Optometrists Network Atropine Information MedlinePlus/ADAM (US) On Amblyopia treatment of older children NEI/NIH Apr 2005 The Early Adaptive Syndrome [Apell and Streff; Jan '63] Blindness Leber's Congenital Amaurosis [I Russel Eggitt] (UK) Leber's Congenital Amaurosis Texas School for the Blind (US) Leber's Congenital Amaurosis Foundation Fighting Blindness (UK) Amaurosis Fugax About Amaurosis Fugax APMA Amaurosis Fugax and Transient Ischemic Attack Handbook of Ocular Disease Management Hemianopsia About Hemianopsia Brief Note about Homonymous Hemianopsia Royal Soc for the Blind (AU) Brief facts about Stroke Related Sight Loss Hemianopsia RNIB (UK) Color Vision Defects How do we see colors? HHMI (US) Color Vision Deficiency AOA (US) Color Vision Problems HON (CH) About Color Vision Color and the Aging Eye Congenital Color Vision Defects LKC Technologies Inc (US) Ishihara Test for Color Blindness On the Evolution of Color Vision [M Rowe] via TalkOrigins Archive and Ecological importance of trichromatic vision to primates [Dominy and Lucas] letter to Nature 2001 Color & Vision Database San Diego (US) The Achromatopsia Network Berkeley CA (US) Putting Color Back Where It Belongs [A Revonsuo; commentary] Consciousness and Cognition 10 2001 About Rainbows [BT Lynds] Diplopia Diplopia LowVisionorg About Double Vision Strabismusorg Red Lens Test Johns Hopkins U (US) The Differential Diagnosis of Diplopia [A Finlay] Scotoma Some brief notes about Scotoma SpEdEx A case of Absolute Scotoma [CH Gonzalez] UMDNJ Scotoma information
Have your eyes ever been watery, itching, swollen or just plain irritated? Do you suffer regularly from these uncomfortable eye irritations? If so, you may be one of the over 22 million people in the United States that suffer from the most common eye allergy--allergic conjunctivitis (this condition is also referred to as ocular allergies or allergy eyes).There is a thin clear mucous membrane that lines the inside of your eyelids and the white part of your eye called the conjunctiva. When this membrane becomes irritated by an external allergen, the resulting condition is called allergic conjunctivitis. As the name suggests, this condition is an allergy of the eye, no different than other common allergies in terms of its causes and prevention.The conjunctiva membrane can also become irritated by viral and bacterial infections or by exposure to a chemical substance. In these cases, the resulting symptoms may be similar to allergic conjunctivitis, but the conditions are called infectious conjunctivitis (viral or bacterial) and chemical conjunctivitis respectively. It is critical to determine whether you have allergic conjunctivitis or one of these other forms of conjunctivitis since these conditions require very different treatments.What is an allergic response? An allergic response is an unwarranted over-reaction of the body's immune system to foreign substances known as allergens, which the body wrongly perceives as a potential threat. As mentioned above, allergic conjunctivitis is an allergy that affects the membrane that covers the inside of your eyelids and the white part of your eye. When the eye comes into contact with certain allergens, an allergic response can result.Common allergens that cause allergic conjunctivitis include:Plant pollens Animal dander Dust mites Mold spores Grass and ragweed Cosmetics and perfumes Skin medicines Air pollution Contact lenses and contact lens solutions Common symptoms of allergic conjunctivitis include: Itchy eyes and eyelids
Watery/mucus discharge from the eye Dilated vessels in the conjunctiva Burning sensation around the eyes Redness around the eyes Swollen eyelids Blurred vision Sensation of fullness in the eyes or eyelid Sensation of foreign body in the eye An urge to rub the eyes Once allergic conjunctivitis has occurred, there are several environmental factors that can affect the intensity and duration of the condition. Hot and dry weather usually aggravates the condition and intensifies the symptoms, whereas cold and wet weather generally alleviates and soothes the symptoms.Two Types of Allergic Conjunctivitis There are two types of allergic conjunctivitis, seasonal and perennial. The former is the more common of the two occurring in the majority of people who suffer from this condition. It is associated with seasonal allergies which commonly occur during the spring and summer months and is usually caused by exposure to airborne allergens, such as grass and plant pollens. Perennial allergic conjunctivitis persists throughout the year and is generally triggered by indoor allergens such as animal dander, dust mites and mold spores.It's important to remember that although allergic conjunctivitis may be extremely irritating and uncomfortable, it will not cause any damage to the internal structure of your eye nor will it cause any permanent damage to your eyesight or eyelids in any way.Conjunctivitis refers to any inflammatory condition of the membrane that lines the eyelids and covers the exposed surface of the sclera. It is the most common cause of "red eye." The etiology can usually be determined by a careful history and an ocular examination, but culture is occasionally necessary to establish the diagnosis or to guide therapy. Conjunctivitis is commonly caused by bacteria and viruses. Neisseria infection should be suspected when severe, bilateral, purulent conjunctivitis is present in a sexually active adult or in a neonate three to five days postpartum. Conjunctivitis caused by Chlamydia trachomatis or Neisseria gonorrhoeae requires aggressive antibiotic therapy, but conjunctivitis due to other bacteria is usually self-limited. Chronic conjunctivitis is usually associated with blepharitis, recurrent styes or meibomianitis. Treatment requires good eyelid hygiene and the application of topical antibiotics as determined by culture. Allergic conjunctivitis is distinguished by severe itching and allergen exposure. This condition is generally treated with topical antihistamines, mast-cell stabilizers or anti-inflammatory agents.the conjunctiva is a thin, translucent, relatively elastic tissue layer with both bulbar and palpebral portions. The bulbar portion of the conjunctiva lines the outer aspect of the globe, while the palpebral portion covers the inside of the eyelids. Underneath the conjunctiva lie the episclera, the sclera and the uveal tissue layers The clinical term "red eye" is applied to a variety of distinct infectious or inflammatory ocular disease processes that involve one or more tissue layers of the eye. Red eye is the most common ocular problem seen by primary care physicians.The term "conjunctivitis" encompasses a broad group of conditions presenting as inflammation of the conjunctiva. The inflammation can be hyperacute, acute or chronic in presentation and infectious or noninfectious in origin. Conjunctivitis is the most common cause of red eye.Most frequently, conjunctivitis (and thus red eye) is caused by a bacterial or viral infection. Sexually transmitted diseases such as chlamydial infection and gonorrhea are less common causes of conjunctivitis. However, these infections are becoming more prevalent and are important to recognize because of their significant associated systemic, ocular and social implications.Ocular allergy in its many forms is one of the major causes of chronic conjunctivitis. Blepharitis (inflammation of the eyelid margin), dry eye and the prolonged use of ophthalmic medications, contact lenses and ophthalmic solutions are also relatively frequent causes of chronic conjunctival inflammation.This article highlights key features in the clinical history and ocular examination that can help family physicians to formulate a differential diagnosis and a management plan for patients with conjunctivitis or red eye of uncertain etiology (Figure ). The diagnosis and treatment of the most common forms of conjunctivitis are also reviewed. The history of a patient with conjunctivitis should include a thorough ocular, medical and medication history. This should establish whether the condition is acute, subacute, chronic or recurrent, whether it is unilateral or bilateral, and whether it is associated with any specific environmental or work-related exposure. Many symptoms of conjunctivitis, such as tearing, irritation, stinging and burning are nonspecific. However, certain symptoms may strongly suggest a particular diagnosis.Itching Itching is the hallmark of allergic conjunctivitis, as well as other forms of allergic eye disease. The itching may be mild to severe. In general, a red eye in the absence of itching is not caused by ocular allergy.A history of recurrent itching or a personal or family history of hay fever, allergic rhinitis, asthma or atopic dermatitis is also suggestive of ocular allergy. Mild itching can also be a feature of blepharitis, dry eyes and, occasionally, bacterial or viral conjunctivitis. Discharge The type of ocular discharge, such as serous (watery), mucoid, mucopurulent or grossly purulent, can be helpful in determining the underlying cause of conjunctival inflammation (Table ). A serous discharge is most commonly associated with viral or allergic ocular conditions. A mucoid (stringy or ropy) discharge is highly characteristic of allergy or dry eyes. A mucopurulent or purulent discharge, often associated with morning crusting and difficulty opening the eyelids, strongly suggests a bacterial infection. The possibility of Neisseria gonorrhoeae infection should be considered when the discharge is copiously purulent. The preceding generalizations about ocular discharges can be helpful in distinguishing between viral and simple bacterial conjunctivitis. However, in the absence of a definitive diagnosis, many physicians elect to empirically prescribe topical antibiotics. Unilateral or Bilateral Conjunctivitis Allergic conjunctivitis is almost always secondary to environmental allergens and, therefore, usually presents with bilateral symptoms. Infections caused by viruses and bacteria (including Chlamydial organisms) are transmissible by eye-hand contact. Often, these infections initially present in one eye, with the second eye becoming involved a few days later. Since chronic unilateral conjunctivitis can have a number of causes, it often presents a difficult diagnostic dilemma. Therefore, patients with this condition should be referred for full ophthalmic assessment to rule out less common entities, such as keratitis, nasolacrimal duct obstruction, occult foreign body and conjunctival neoplasia Pain, Photophobia and Blurred Vision
Pain and photophobia are not typical features of a primary conjunctival inflammatory process. If these features are present, the physician should consider more serious underlying ocular or orbital disease processes, including uveitis, keratitis, acute glaucoma and orbital cellulitis. Similarly, blurred vision that fails to clear with a blink is rarely associated with conjunctivitis. Patients with pain, photophobia or blurred vision should be referred to an ophthalmologist. Other Aspects of the History A recent upper respiratory tract infection in the patient's home, school or workplace suggests a diagnosis of infectious conjunctivitis, especially of adenoviral origin. Chlamydial or gonococcal infection may be suggested by the patient's sexual history, including a history of urethral discharge. The physician should also inquire about the patient's use of systemic and over-the-counter topical medications (e.g., vasoconstrictors or artificial tears), as well as the use of cosmetics and contact lenses, since any of these can produce acute or chronic conjunctivitis. Most patients do not regard nonprescription eye medications as possible causes of ocular problems. Therefore, unless questioned directly, they generally do not volunteer information about their use of these medications. A history of collagen vascular disease or the use of diuretics or antidepressant medications should alert the physician to the possibility of dry eyes. Physical Clues to the Etiology of Conjunctivitis The patient should be examined in a well-lit room. Before performing the ocular examination, the physician should search for regional lymphadenopathy and should examine the face and eyelids carefully. Viral or chlamydial inclusion conjunctivitis typically presents with a small, tender, preauricular or submandibular lymph node. Toxic conjunctivitis secondary to topical medications can also produce a palpable preauricular node. Palpable adenopathy is rare in acute bacterial conjunctivitis. The exception is hyperacute conjunctivitis caused by infection with Neisseria species. Other facial clues to the etiology of conjunctivitis include the presence of herpes labialis or a dermatomal vesicular eruption suggestive of shingles. Either of these findings may indicate a herpetic source of conjunctivitis. Diagnostic Tests Cultures usually are not required in patients with mild conjunctivitis of suspected viral, bacterial or allergic origin. However, specimens for bacterial cultures should be obtained in patients who have severe inflammation (e.g., hyperacute purulent conjunctivitis) or chronic or recurrent conjunctivitis. Cultures also should be obtained in patients who do not respond to treatment. Several laboratory procedures can be used to identify chlamydial infections. These include cell culture, direct fluorescent monoclonal antibody staining of smears, enzyme immunoassays for Chlamydia organisms, DNA hybridization assays and a polymerase chain reaction test to identify chlamydial antigens. Many ophthalmologists obtain conjunctival cytology scrapings for Gram's staining and/or Giemsa staining to help characterize the conjunctival inflammatory response. The findings can be helpful, particularly for diagnosing allergic, chlamydial and certain atypical forms of conjunctivitis in which the clinical diagnosis is not immediately apparent. Bacterial Conjunctivitis Hyperacute Bacterial Conjunctivitis Hyperacute bacterial conjunctivitis is a severe, sight-threatening ocular infection that warrants immediate ophthalmic work-up and management. The infection has an abrupt onset and is characterized by a copious yellow-green purulent discharge that reaccumulates after being wiped away. The symptoms of hyperacute conjunctivitis, which typically are rapidly progressive, also include redness, irritation and tenderness to palpation. Patients demonstrate marked conjunctival injection, conjunctival chemosis (excessive edema), lid swelling and tender preauricular adenopathy. The most frequent causes of hyperacute purulent conjunctivitis are N. gonorrhoeae and Neisseria meningitidis, with N. gonorrhoeae being by far the more common. These two infections have similar clinical presentations, and they can be distinguished only in the microbiology laboratory. Gonococcal ocular infection usually presents in neonates (ophthalmia neonatorum) and sexually active young adults. Affected infants typically develop bilateral discharge three to five days after birth (Figure ). Transmission of the Neisseria organism to infants occurs during vaginal delivery. In adults, the organism is usually transmitted from the genitalia to the hands and then to the eyes. If a gonococcal ocular infection is left untreated, rapid and severe corneal involvement is inevitable. The resulting ulceration and, ultimately, perforation lead to profound and sometimes permanent loss of vision. Infected infants may also have other localized gonococcal infections, such as rhinitis or proctitis, or they may have disseminated gonococcal infection, such as arthritis, meningitis, pneumonia or sepsis. The diagnostic work-up for a gonococcal ocular infection includes immediate Gram staining of specimens for gram-negative intracellular diplococci, as well as special cultures for Neisseria species. All patients should be treated with systemic antibiotics supplemented by topical ocular antibiotics and saline irrigation. Because of the increasing prevalence of penicillin-resistant N. gonorrhoeae in the United States, ceftriaxone (Rocephin), a third-generation cephalosporin, is currently the systemic drug of choice. Spectinomycin (Trobicin) or oral ciprofloxacin (Cipro) can be used in patients who are allergic to penicillin. Over percent of patients with gonococcal conjunctivitis have concurrent chlamydial venereal disease. For this reason, it is advisable to treat patients with supplemental oral antibiotics that are effective against Chlamydia species. Acute Bacterial Conjunctivitis Acute bacterial conjunctivitis typically presents with burning, irritation, tearing and, usually, a mucopurulent or purulent discharge (Figure ). Patients with this condition often report that their eyelids are matted together on awakening. Conjunctival swelling and mild eyelid edema may be noted. The symptoms of acute bacterial conjunctivitis are far less severe, less rapid in onset, and progress at a much slower rate than those of hyperacute conjunctivitis. The three most common pathogens in bacterial conjunctivitis are Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus. Infections with S. pneumoniae and H. influenzae are more common in children, while S. aureus most frequently affects adults , .Although acute bacterial conjunctivitis is usually self-limited and does not cause any serious harm, there are several justifications for treatment. These include decreasing patient morbidity by shortening the course of the disease, reducing person-to-person spread, lowering the risk of sight-threatening complications such as corneal ulceration, and eliminating the risk of more widespread extraocular disease. Cultures should be obtained in certain patients, including young children and debilitated persons. However, empiric treatment with a topical medication is a safe and cost-effective approach in most patients with clinically mild acute bacterial conjunctivitis. Unfortunately, no single broad-spectrum antibiotic covers all potential conjunctival bacterial pathogens. In choosing an appropriate topical antibiotic, the physician should keep in mind the most likely conjunctival pathogens, as well as the cost and side effects of each medication. Since most adult cases of acute bacterial conjunctivitis are caused by gram-positive organisms, it is best to choose an antibiotic with adequate gram-positive coverage (in particular, good staphylococcal coverage).The clinical response to the antibiotic should be assessed after the patient has completed a short course of therapy. If the inflammation has resolved, the antibiotic should be discontinued. However, if the condition has not improved, an ophthalmologist should be consulted. In such patients, laboratory test results can be used to direct changes in therapy.Examples of currently available topical broad-spectrum antibiotics include erythromycin ointment and bacitracin-polymyxin B ointment (e.g., Polysporin ophthalmic ointment), as well as combination solutions such as trimethoprim-polymyxin B (e.g., Polytrim). These medications are well tolerated, and they provide excellent coverage for most conjunctival pathogens in both children and adults. In general, ointments are better tolerated by young children, who are less apt to complain about associated blurring of vision. Solutions are preferred by most adolescents and adults. Aminoglycosides, such as gentamicin (Garamycin), tobramycin (Tobrex) and neomycin are inexpensive choices for the treatment of acute bacterial conjunctivitis. These agents provide good gram-negative coverage, but they have relatively poor gram-positive coverage, including incomplete coverage of Streptococcus and Staphylococcus species. Furthermore, aminoglycosides are associated with a relatively high incidence of toxicity to the corneal epithelium (primarily with prolonged use). Neomycin, in particular, can cause local oculocutaneous allergic reactions. For this reason, topical ophthalmic preparations containing neomycin probably should be avoided as first-line therapy. The percent sulfacetamide solution (Bleph- ) is still a commonly prescribed topical antibiotic for conjunctivitis. This bacteriostatic agent has weak to moderate activity against many gram-positive and gram-negative organisms, including those that commonly cause conjunctivitis. Although sulfacetamide is less effective than some of the other drugs mentioned in this article, it is inexpensive and well tolerated. A rare potential treatment side effect is Stevens-Johnson syndrome. In topical form, tetracycline and chloramphenicol (Chloromycetin) are commonly used to treat bacterial conjunctivitis. Tetracycline is available only in an ointment form. Chloramphenicol, which is available in both drop and ointment forms, has a broad spectrum of antimicrobial activity. Although chloramphenicol is generally well tolerated, topical application of this agent has been associated with a few cases of aplastic anemia. For this reason, chloramphenicol is not widely prescribed in the United States. The fluoroquinolones, which include ciprofloxacin (Ciloxan), ofloxacin (Ocuflox) and norfloxacin (Chibroxin), are a new class of potent topical antimicrobials. Agents from this class are commonly used to treat bacterial keratitis. Given the generally benign, self-limited nature of acute bacterial conjunctivitis, the high cost of topical fluoroquinolones, their poor coverage of Streptococcus species and the potential for developing resistant pathogens with indiscriminate use of this antibiotic class, the fluoroquinolones generally should be reserved for use in more severe ocular infections, including bacterial keratitis. Chronic Bacterial Conjunctivitis and Blepharitis Chronic bacterial conjunctivitis is most commonly caused by Staphylococcus species, although other bacteria are occasionally involved. This type of conjunctivitis often develops in association with blepharitis, which is a common but often unrecognized inflammatory condition related to bacterial colonization of the eyelid margins. Some cases of chronic bacterial conjunctivitis are also associated with facial seborrhea. The symptoms of chronic bacterial conjunctivitis vary and can include itching, burning, a foreign-body sensation and morning eyelash crusting. Signs of this conjunctival condition include flaky debris, erythema and warmth along the lid margins, as well as eyelash loss and bulbar conjunctival injection. Some patients with chronic bacterial conjunctivitis also have recurrent styes and chalazia (lipogranulomas) of the lid margin. The meibomian glands are sebaceous glands that line the posterior lid margin behind the eyelashes. These glands secrete an important oily component of the tear film. When inflamed, the meibomian glands malfunction, producing chronic inflammation of the eyelid margins and the conjunctiva as well as irritating dry-eye symptoms. This condition is referred to as meibomianitis. Chronic inflammation of the meibomian glands and eyelid margins is a predisposing factor for the formation of chalazia within the eyelids. Blepharoconjunctivitis and meibomianitis are common associated findings in patients with acne rosacea. This skin disorder typically affects adults between and years of age and occurs more commonly in women than in men. Diagnostic clues include a history of periodic facial flushing (usually in response to the consumption of certain foods or alcohol) and the presence of erythematous and telangiectatic skin changes on the forehead, cheeks, chin and nose. Some patients also have acneiform lesions and rhinophyma. Ocular findings include recurrent chalazia and styes secondary to chronic blepharitis and meibomianitis, as well as keratitis and dry eyes . The work-up of patients with chronic conjunctivitis and blepharoconjunctivitis involves culturing the conjunctiva and the eyelid margins to identify the predominant bacterial pathogen. Treatment includes the establishment of good eyelid hygiene using warm compresses and eyelid margin scrubs and the application of appropriate topical antimicrobials (e.g., erythromycin). Patients with meibomianitis and acne rosacea often benefit from oral tetracycline therapy. Systemic tetracyclines are contraindicated in nursing mothers, pregnant women and children. Topical metronidazole (Metrogel) is helpful in some patients with acne rosacea. Ocular Chlamydial Infections Ocular Chlamydia trachomatis infection can occur in two distinct clinical forms: trachoma (associated with serotypes A through C) and inclusion conjunctivitis (associated with serotypes D through K). Trachoma, a chronic keratoconjunctivitis, is the most common cause of ocular morbidity and preventable blindness throughout the world. It is a major public health concern in the rural areas of developing countries, particularly in Africa, Asia and the Middle East. , Active trachoma is uncommon in North America. However, patients who have immigrated to North American countries from regions in which trachoma is endemic frequently present to ophthalmologists with cicatricial ocular and eyelid changes secondary to previous recurrent infections Inclusion conjunctivitis is a common, primarily sexually transmitted disease that occurs in both newborns (ophthalmia neonatorum) and adults (adult inclusion conjunctivitis). It is the most frequent cause of conjunctivitis in neonates, followed, in order of decreasing prevalence, by infections with several bacteria species and, finally, N. gonorrhoeae.Infants who are exposed during vaginal delivery to C. trachomatis from the mother's infected cervix develop tearing, conjunctival inflammation, moderate discharge and eyelid swelling five to days after birth Ophthalmic referral is essential. Neonatal inclusion conjunctivitis usually responds to topical antibiotics. However, this condition can be associated with otitis media, and respiratory and gastrointestinal tract infections. Such infants should be treated with a two-week course of systemic erythromycin.Adult inclusion conjunctivitis typically presents in young, sexually active persons between and years of age. Transmission most often occurs by autoinoculation from infected genital secretions The usual presentation is subacute or chronic infection characterized by unilateral or bilateral redness, mucopurulent discharge, a foreign-body sensation and preauricular adenopathy. Laboratory tests are indicated in neonates and adults with suspected inclusion conjunctivitis. At least percent of affected adults have concurrent, possibly asymptomatic chlamydial urethritis or cervicitis.Coinfection with pathogens that cause other sexually transmitted diseases (e.g., syphilis and gonorrhea) is not uncommon. Therefore, once a diagnosis has been established, a genital work-up of the patient and his or her sexual contacts is indicated before antibiotic treatment is initiated. Treatment consists of a two- to three-week course of oral tetracycline, doxycycline, minocycline (Minocin) or erythromycin. A single g dose of azithromycin (Zithromax) is recommended for adults with lower genital tract infection, but a longer course may be necessary in patients with chlamydial conjunctivitis.Viral Conjunctivitis Adenovirus is by far the most common cause of viral conjunctivitis, although the condition can also be caused by other viruses. Viral conjunctivitis often occurs in community epidemics, with the virus transmitted in schools, workplaces and physicians' offices. The usual modes of transmission are contaminated fingers, medical instruments and swimming pool water. Proper hand and instrument washing following patient contact can help to reduce the spread of this highly contagious infection. Patients with viral conjunctivitis typically present with an acutely red eye, watery discharge, conjunctival swelling, a tender preauricular node, and, in some cases, photophobia and a foreign-body sensation. Occasionally, patients also have subconjunctival hemorrhage . Both eyes may be affected simultaneously, or the second eye may become involved a few days after the first eye .Some patients have an associated upper respiratory tract infection. Since the ocular infection is contagious for at least seven days, patients should be instructed to avoid direct contact with other persons for at least one week after the onset of symptoms. Treatment is supportive. Cold compresses and topical vasoconstrictors may provide symptomatic relief. Topical antibiotics are rarely necessary, because secondary bacterial infection is uncommon. Herpes simplex virus keratoconjunctivitis can closely mimic the presentation of ocular adenovirus infection. In such patients, topical corticosteroid therapy can lead to severe ocular complications as a result of uncontrolled virus proliferation. Therefore, topical corticosteroids should not be used in the management of infectious conjunctivitis unless under the direction of an ophthalmologist. Furthermore, viral conjunctivitis is generally benign and self-limited. Treatment with corticosteroids can prolong the course of the disease and also place the patient at risk for other steroid-induced ocular complications, such as glaucoma and cataracts.Ocular infections due to herpes simplex and herpes zoster are becoming more prevalent as the incidence of human immunodeficiency virus infection continues to increase. Patients with suspected ocular herpetic infection should be referred to an ophthalmologist. Ocular herpes simplex and herpes zoster are often managed with topical and/or systemic antiviral agents. Various topical agents, including trifluridine (Viroptic), may be helpful. Useful systemic antiviral agents include acyclovir (Zovirax), famciclovir (Famvir) and valacyclovir (Valtrex).Allergic Conjunctivitis Ocular allergy encompasses a spectrum of distinct clinical conditions usually characterized by itching. The most common of these conditions is seasonal allergic rhinoconjunctivitis, also called hay fever rhinoconjunctivitis. Seasonal allergic rhinoconjunctivitis is an IgE-mediated hypersensitivity reaction precipitated by small airborne allergens. The condition is usually, although not invariably, seasonal. Patients typically experience intermittent bouts of itching, tearing, redness and mild eyelid swelling. The personal or family history is often positive for other atopic conditions, such as allergic rhinitis, asthma or eczema.Treatment measures for seasonal allergic rhinoconjunctivitis include allergen avoidance, cold compresses, vasoconstrictors, antihistamine drops, topical nonsteroidal anti-inflammatory agents and mast-cell stabilizers such as cromolyn sodium (Crolom) or lodoxamide (Alomide). Oral antihistamines help to relieve symptoms in many patients.Allergic conjunctivitis has also been successfully treated with levocabastine (Livostin), which is a topical antihistamine, and with ketorolac tromethamine (Acular) and diclofenac sodium (Voltaren), which are topical nonsteroidal anti-inflammatory agents. All three agents are well tolerated and have a rapid onset of action. In severe cases, a short course of topical corticosteroids is often required for adequate symptomatic relief. However, corticosteroid therapy should only be administered under the direction of an ophthalmologist. Immunotherapy can be beneficial in some patients with allergic conjunctivitis.Other Causes of Conjunctivitis Common noninfectious causes of conjunctivitis include dry eye and inflammation of the conjunctiva related to use of medications or wearing contact lenses. These entities should be considered in patients with chronic signs and symptoms that do not appear to be of infectious or allergic flowers origin pregnant, target, google, yahoo, health, search engines hotmail parent women men hair usher pregnancy dog dods cat cats heart free pictures.