The cornea is the first line of defense against injury to the eye. The dome-shaped, clear tissue of the cornea covers the iris, the colored part of the eye, and the pupil, the hole that adjusts to let light into the eye. Diseases that damage the cornea cause the clear tissue to become cloudy or hazy, decreasing vision. There are a number of diseases that affect the cornea.
Fuchs' Dystrophy
Fuchs' dystrophy is an inherited, progressive disease that destroys the epithelial cells of the cornea. As the epithelial cells disappear, the cornea swells, changing its shape, and becomes hazy. Vision decreases as a result. The swelling epithelium causes pain and severe vision loss, as painful blisters form on the surface of the cornea. Ophthalmic drops may be used to decrease swelling and pain, but corneal transplant is often required to restore vision.
Iridocorneal Endothelial Syndrome (ICE)
The National Eye Institute claims that ICE is a corneal disease that usually affects women between the ages of 30 and 50. The disease is usually present in only one eye. Three symptoms define the disease: swelling of the cornea; glaucoma, or high pressure within the eye; and changes in the iris caused by endothelial cells from the cornea falling onto the iris. Cells from the corneal endothelium block fluid drainage from the eye, causing high eye pressure. Glaucoma medications reduce pressure within the eye, but corneal transplant may be necessary to improve vision.
Keratitis
Keratitis is the presence of corneal ulcers caused by corneal infection, the University of Michigan Kellogg Eye Center states. Bacteria or fungi entering the eye cause pain, redness, blurred vision and light sensitivity. Corneal erosion may occur. Keratitis is treated with antibiotic or antifungal drops or systemic medication; some cases may require steroid eyedrops to reduce inflammation. A scarred or thinned cornea may necessitate corneal transplant.
Keratoconus
Keratoconus, a corneal dystrophy, affects one in 2,000 young Americans in their teens and twenties, the National Eye Institute reports. Keratoconus is sometimes inherited, but it can also result from injury or systemic diseases, such as Down syndrome. The middle part of the cornea thins and then bulges outward in keratoconus, causing blurriness and distortion. The corneal tissue may swell and scar. Keratoconus usually affects both eyes; glasses and well-fitting contact lenses can be used to improve vision, unless severe scarring occurs, at which point a corneal transplant may be needed.
Lattice Dystrophy
Lattice dystrophy scars the cornea when abnormal protein fibers, called amyloid, are deposited in the cornea. Erosion of the epithelium causes severe pain from exposed nerves. The natural curve of the cornea is changed, affecting vision. Scarring of the retina usually occurs by the time a person with the disease reaches age 40 and may require corneal transplant.
Ocular Herpes
Ocular herpes is a painful viral infection caused by the herpes simplex virus. Symptoms of ocular herpes include tearing, swelling around the eyes, redness and light sensitivity. Ocular herpes infections often recur, causing serious damage to the cornea over time. Superficial infection of the top layers of the cornea may be treated with antiviral eyedrops. Deeper infections of the stromal layer of the cornea may require steroid treatment, but this should be done only under your doctor's supervision, AllAboutVision.com states, because steroid drops suppress the eye's immune system. Scarring may occur, leading to a need for corneal transplant.
Pterygium
Pterygium is a benign, pinkish, triangular growth on the cornea that occurs most frequently in sunny climates. Pterygium grows slowly and may return if surgically removed. Surgical removal may be tried if the growth is affecting a person's vision.
