A wide range of diseases afflict the cornea, which is the clear, outer layer of the eyes. Corneal diseases may include infections caused by pathogenic agents such as bacteria or viruses. In addition, dystrophies and ectasias are diseases in which the cornea begins to break down or wear out. Many types of cornea diseases respond well to treatment if handled by a specialist.
The cornea consists of five layers, and each of these may be affected by disease. From exterior to interior, these layers are the corneal epithelium, Bowman’s layer, the corneal stroma, Descemet’s membrane (or the posterior limiting membrane), and the corneal endothelium.
Although they stem from various issues, dystrophies may cause a loss of vision clarity. Fuchs’ dystrophy is one of the most common types, causing vision cloudiness over time. In this disease, the cells of the endothelium break down very gradually. One of their functions includes pumping water out of the stroma. When the endothelium cells cease to perform this function, the cornea may begin to swell, leading to poor vision and may even cause small blisters than may painfully rupture.
A type of dystrophy that affects the stroma directly is lattice dystrophy. Under regular function, the stroma serves as a support network for the other elements of the cornea. However, if the stroma begins to produce fibers at an accelerated rate, a lattice-like distortion of the vision may occur. Often, patients with lattice dystrophy see small dots, and as the disease progresses, these dots accumulate into larger cloudy areas.
Another type of disorder, epithelial basement membrane dystrophy, or map-dot-fingerprint dystrophy, affects the corneal epithelium. As cells develop in abnormal patterns, they may cause irregularity of the surface, affecting vision and may even cause painful erosions. Individuals with this disorder may display grayish patterns on the epithelium.
Many types of pathogenic infections can affect the cornea, though one of the most common is ocular herpes. Caused by the same virus that causes cold sores, ocular herpes can lead to lesions on the eyes and on the eyelids. Ocular herpes can also cause secondary inflammation that may lead to blindness if left untreated.
If you are having eye pain or unusual vision problems, consult your physician.
About the Author: Eleanor Cheng, MD serves as an Associate at Corneal Associates of New Jersey. She has been practicing ophthalmology for nearly a decade.
