The cornea is the clear layer in front of the iris and pupil. It protects the iris and lens and helps focus light on the retina. It is composed of cells, protein, and fluid. The cornea looks fragile but is almost as stiff as a fingernail. However, it is very sensitive to touch.
Corneal disorders include the following:
CORNEAL ABRASION – Corneal abrasions, a cut or scratch of the clear window of the eye, are associated with light sensitivity, pain, and tearing. Corneal abrasions may cause mild discomfort or severe pain, depending on the size of the abrasion. Treatment may include lubrication, bandage contact lens, eye patching and/or preventative antibiotic ointment. The cornea is the fastest healing tissue in the human body, thus, most corneal abrasions will heal within 24-36 hours.
BAND KERATOPATHY – Band keratopathy is a calcium deposit at the 3-9 o’clock positions in the front layer of the cornea. This deposit of calcium may spread across the cornea in band like appearance. The condition is caused by inflammations, trauma, chronic ocular disease, or even systemic diseases.
Treatment is necessary when the deposits affect vision. If the band of calcium deposits affect visions, chemical removal can be considered. Usually, vision improves following the removal of calcium from the cornea.
CORNEAL DELLEN – Dellen are localized areas of thinning, or drying, of the peripheral cornea. Dellen are usually located adjacent to an area of tissue swelling, tissue growth, inflammation, or eyelid abnormality. These abnormalities may alter the eye’s normal ability to spread the tear layer uniformly over the cornea.
Initial treatment involves the use of eye lubrication with artificial tears, and/or ointments. Occasionally bandage contact lenses are used to protect the cornea and promote healing.
CORNEAL ENDOTHELIAL DYSTROPHY – Corneal endothelial dystrophies are disorders involving the layer of the cornea closest to the inside of the eye. This condition may result in thickening, cloudiness of the cornea with resultant decreased vision over time. Glare and blurred vision are common upon awakening. The condition, which is usually hereditary usually develops after age 50. Many patients are comforted by the gentle use of a warm hair dryer for 5-10 minutes to dry the cornea. Salt solutions like Muro 128 are helpful. Treatment decreases symptoms, but does not effect the disease.
CORNEAL EPITHELIAL DYSTROPHY Corneal epithelial dystrophies are disorders involve the front surface of the cornea which result in decreased vision due to cloudiness, and surface irregularities of the cornea. If the corneal lesions loose their outer surface layer, like any other wound, they become very painful. These lesions or erosions may become recurrent. Half of the corneal epithelial dystrophies are hereditary in nature.
CORNEAL STROMAL DYSTROPHY – Corneal stromal dystrophies are disorders of the middle layer of the cornea. Corneal dystrophies are inherited conditions diseases which may cause symptoms such as glare and/or cloudy vision. Some are only be visible under the microscope and may never affect your vision. Others result in intense glare with diminishing visual acuity.In these cases, a cornea transplant may be necessary to restore useful vision.
RECURRENT CORNEAL EROSIONS – Recurrent corneal erosions are a disruption of the front surface of the cornea, which recurs in the same area of the cornea. The normal history is one in which the patient initially had a cut or abrasion to the cornea, which healed normally. Some time later the patient wakes up in the middle of the night with intense pain, blurred vision, and a water eye. Fortunately, the cornea heals rapidly, within 24 hours the cornea has re-surfaced the eroded area. For some unknown reason, when the cornea heals the new tissue does not properly glue down to the underlying surface. The episodes may occur as frequently as weekly or as rarely as years later.
The diagnosis of recurrent corneal erosion is often made by history only. Treatment may range from initial patching and use of medicated drops or ointments, to Laser procedures to aid tissue attachment and stability.
CORNEAL NEOVASCULARIZATION (neo’-vas-cu-lar-ize-a-tion) – Corneal neovascularization describes new growth of, undesired blood vessels into the normally clear cornea. These blood vessels are a response to lack of oxygen or significant inflammation of the cornea. When such vascularization of the cornea is observed, it is important to attempt to diminish and hopefully stop this vascular growth. A common cause of neovascularization is over-wear or sleeping with contact lenses. When left uncontrolled, progressive corneal neovascularization may lead to diminished or lost vision.
CORNEAL SCAR – The transparency of the cornea can be damaged by disease or by injury to a degree which affects vision. A scar may develop from injury. If the scar is in the middle of the cornea it may affect vision alternatively, if there is scarring in the peripheral area vision will not be affected. If the vision loss due to corneal scarring significantly reduces vision either LASIK or a corneal transplant can restore sight.
CORNEAL ULCER – A corneal ulcer is an area of tissue loss from the surface of the cornea. Corneal ulcers may result from bacterial, fungal, or viral infection of the corneal tissue or loss of innervation of the pain nerves to the cornea. All corneal ulcers are serious, sight-threatening lesions that require immediate, aggressive treatment and management. Eye pain, light sensitivity, decreased vision and tearing are common symptoms of these lesions. Treatment is dependent on the cause of inflammation Frequent examination will be necessary until the ulcer has completely resolved.
CORNEAL FOREIGN BODY – Corneal foreign body is material that has become embedded in the front part of the eye. Symptoms vary greatly depend on severity; usually producing pain, light sensitivity and tearing. All foreign bodies, especially dirt, metal or glass must be removed for proper healing to occur. After removal, treatment may include any or all of the following: antibiotic drops or ointment, therapeutic contact lens, eye patching and dilation drops. Return visits are necessary until complete healing has occurred.
FUCH’S DYSTROPHY – Fuch’s Dystrophy is a degeneration of tissue of the most inner layer of the cornea. This corneal degeneration begins with a loss of the cells that keep the cornea clear. When these cells die, the cornea may swell thereby decreasing vision. This swelling may cause the formation of blisters on the corneal surface. If these blisters open, you may experience discomfort, pain and variable vision. One of the chief symptoms of Fuch’s is variability of vision. Swelling of the cornea is usually worse in the morning with a resultant decrease in vision improving as the day goes on.
Fuch’s Dystrophy, often a hereditary condition, affects women more than men. When patients suffer This condition is chronic apart from surgery to decrease pain and/or to improve vision treatment is palliative. Many patients are comforted by the gentle use of a warm hair dryer for 5-10 minutes to dry the cornea. Salt solutions like Muro 128 are helpful, ointment at night drops during the day. Treatment decreases symptoms, but does not effect the disease. If vision decreases to a level that visual functioning is affected a new cornea can be transplanted with a high degree of success
HERPES ZOSTER (SHINGLES) – Herpes zoster, or “shingles,” is a painful viral infection of the nervous system that causes a rash and blistering limited to one region of the body. A Herpes zoster attack usually begins with pain, followed by a rash and blisters. Once the pain begins you have a short window of time to begin a course of oral antiviral medication to shorten the duration of the disease. Get to your primary care doctor immediately.
The eye may become involved in Herpes zoster infections, the eye becomes red with involvement of the cornea. When the eye becomes involved, eye drops which include antibiotics, steroids, or even anti-glaucoma medications. These medications diminish, the risk of scarring, cataracts and glaucoma.
HYPHEMA (hi-fee’-mah) – Hyphema is the accumulation of blood in the space between the cornea and the iris. This space is normally filled with a clear fluid. Trauma may cause a break in the blood vessels with resultant bleeding into the space between the cornea and iris (anterior chamber). The most important concern with the diagnosis of hyphema is the possibility of developing glaucoma. During the reabsorption of the blood cells from the anterior chamber, it is possible for the blood cells to block the drainage system of the front of the eye. This causes the pressure in the eye to rise.
An additional concern is a risk of rebleeding during the first week following the injury. Thus activity should be restricted. Repeated eye examination and treatment are required to minimize damage. Topical and in some cases oral medications are necessary to decrease risks of rebleeding. Sleeping with the head elevated at night will facilitate reabsorption of the blood.
NON-INFECTIOUS CORNEAL INFILTRATES – Non-infectious corneal infiltrates, corneal subepithelial infiltrates and infiltrative keratitis, result from a delayed hypersensitivity to an by-product of bacteria and virus, i.e., allergic reaction. Your body’s immune system responds by sending white blood cells to protect the body. The presence a large number of white blood cells causes an inflammation of the tissue. These corneal infiltrates may cause decreased clarity of the cornea, pain, redness and tearing. Treatment of these conditions may include drops to quiet the eye.
EXPOSURE KERATITIS – The cornea maintains its health and clarity, by being constantly bathed in tear fluid to nourish and lubricate the eye. Exposure keratitis is an inflammation of the cornea that results from drying of the cornea. This drying results from the incomplete closure of the eyelids during the day and/or night while sleeping or from inadequate tear production. The most common symptoms of this condition include discomfort when blinking, a scratchy/gritty sensation, increased sensitivity to light and/or increased tearing of the eyes.
Some environmental conditions contribute to exposure keratitis, such as excessive wind, heat or dry environments.
FILAMENTARY KERATITIS – Filaments or tags of cells and mucus on the corneal surface can be associated with a variety of conditions. Filaments occur most frequently in patients with severe dry eyes and/or inflammatory conditions.
Treatment may require the removal of the loosely attached filaments in the office or a bandage contact lens to protect the irritated corneal surface. When a dry eye is involved, artificial tears may increase comfort and decrease filament formation.
HERPES KERATITIS – Herpes simplex keratitis is an infection of the cornea, caused the same virus as cold sores. A herpetic eye infection may involve an ulcer, or break in the corneal surface. The eye may feel scratchy, red and/or be painful. Vision is usually effected from swelling of “disciform” keratitis. Herpetic keratitis tends to recur, with possible permanent scarring and vision loss.
Early and consistent treatment is important to minimize the risk of eye damage. The herpes virus does not always respond to the initial medication and it may require a change of medications. Treatment may last for months. Vision usually returns to normal, however, repeated reoccurrences associated with permanent scarring may require a corneal transplant to restore vision.
Because herpetic infections tend to recur, it is important to recognize the symptoms and seek early treatment. While the exact cause of recurrence is not fully understood, there is an association with fevers, sun exposure, and steroid medications. It is important not to self-medicate. You must be seen as soon as you suspect symptoms.
SUPERFICIAL KERATITIS (SPK) – Superficial keratitis results from a mild, diffuse inflammation of the outer layer of the cornea tissue. It may be caused by dry eye, foreign particles in the eye, contact lenses, chemical/drug toxicity. Symptoms include mild to moderate discomfort, redness, light sensitivity, and a gritty foreign body sensation.
Treatment begins with the elimination of the cause. Fortunately, the front surface of the cornea heals rapidly, thus, superficial keratitis may resolve without any treatment. Usually lubricating or antibiotic ointments and/or drops will aid in the healing process and provide comfort.
THYGESON’S KERATITIS – Thygeson’s keratitis is an uncommon, chronic inflammatory disease affecting the front layer of the cornea. Symptoms vary from a scratchy, foreign-body sensation to pain with sensitivity to light. This condition usually affects both eyes. Thygeson’s keratitis is characterized by recurrent episodes of surface irritation. A virus is thought to be the culprit but it has never been identified.
Although this disease may continue for several years, episodes respond to treatment to topical steroids. It should be remembered that steroids are powerful medications if incorrectly used it may cause glaucoma, infections or cataracts.
KERATOCONUS (ker-a-toe-CO-nus) – The word keratoconus comes from two Greek words: kerato, meaning cornea, and bonus, meaning cone. The cornea is generally shaped like a dome. The cornea provides protection of the eye and provides the majority of the focusing power of the eye.
Keratoconus, which occurs in 1 out of every 2,000 persons, is an irregular bulging of the central area of the cornea. The condition is due to weakening and thinning of the central portion of the cornea causing a change in shape of the central portion of the cornea. The cornea becomes more conical and distorted causing significant changes in vision which may begin in the late teen years and may not stop until age 40. In some patients, keratoconus appears to be an inherited bilateral (two eye) condition, while in other patients there is no evidence of an inherited disorder.
During the earliest stages of keratoconus, there may be frequent changes of glasses. As the corneal distortion increases, rigid contact lenses may be required to obtain the adequate vision. Contact lenses mask the distortion of the underlying cornea. Most keratoconus patients can be managed with contact lenses which provide good vision and comfort.
When contact lenses can no longer correct vision adequately, or comfortably, surgical replacement of the cornea may be considered. Surgical treatment is necessary in about 10% of the cases. Cornea transplants are highly successful (over 95%). The transplant may not eliminate the need for glasses or contacts.
PELLUCID (pel-lu’-acid) MARGINAL DEGENERATION – Pellucid marginal degeneration describes an uncommon non-inflammatory, thinning of the inferior periphery of the cornea. The condition is more common in males and first noted in patients ranging from 20 to 40 years of age.
The initial symptom is a periodic change of eyeglass prescription due to astigmatism. Glasses may initially correct the vision, however, contact lenses may help in more difficult cases.
SALZMAN’S DEGENERATION – Salzman’s degeneration is a non-inflammatory, progressive, disorder that results in nodular elevations on the cornea. Treatment is necessary only if there are persistent symptoms such as tearing, light sensitivity, or vision loss.
TERRIEN’S DEGENERATION – Terrien’s degeneration is a gradual thinning of the area around the outer edge of the cornea. The thinning takes the form of a trough. It can affect vision by causing surface irregularity. This condition usually affects males appearing in their late teens and older.
Symptoms of this slowly progressive disease include mild irritation, which may help with lubricating drops or ointment and the possible intermittent use of mild steroid drops. Vision-threatening complications are rare.
MOORE’S CORNEAL ULCERATION – Mooren’s ulcer is a severe progressive disease of the peripheral cornea. This auto-immune is frequently painful. The condition may be a benign form, or progressively destructive. Treatment is often frustrating with the use of topical medications, bandage contact lenses, or surgery.
ARCUS JUVENILES OR SENILIS – Arcus Juveniles or senilis is a deposition of lipids causing a white ring at the periphery of the cornea. In general, this condition is benign and age-related.
When younger patients have prominent arcus senilis, there may be an association with elevated blood cholesterol. It is prudent to test cholesterol and lipid levels during the next medical examination.
