Glaucoma, simply put, is the name given to a family of diseases of the eye in which there is slow, chronic, and insidious degeneration of the nerve, known as the “optic nerve”, which travels from eye to brain, carrying the signals that convey sight.
The degeneration of glaucoma is typically, but not always, related to the buildup of pressure inside the eye. However, about one-third of glaucoma patients have “normal” eye pressure, so screening for glaucoma by checking only the pressure in the eye will unfortunately miss the diagnosis in many affected people. Glaucoma afflicts approximately 5 - 7% of the adult population of the United States, and glaucoma is 5 times as common in family members of affected individuals as it is in the general population.
Most people mistakenly assume that glaucoma causes “tunnel vision”, but this is not really a very accurate concept. The varieties of vision loss that occur in glaucoma do have characteristic patterns, and the loss does involve “side” vision, primarily, but the loss varies from person to person in the specifics and details in an almost infinite variety of subtle ways. Modern testing can easily detect and track the loss, with far greater sensitivity than the patient’s own subjective impressions can yield.
In popular culture, glaucoma is sometimes referred to as the “sneak thief of sight," because it is usually painless and proceeds very slowly, often taking place over many years, so that the affected person is typically unaware even of having the condition until quite late in the course of disease. In fact, studies consistently show that about half the glaucoma in the United States is undiagnosed and thus about one-half of affected patients are unaware they even have the condition. This is unfortunate, because glaucoma is overwhelmingly a treatable condition when diagnosed properly and early, and when treated knowledgeably. People with glaucoma who come to diagnosis relatively early, and who avail themselves of proper care, will typically have excellent vision all of their lives. When left untreated, however, glaucoma can lead to irreversible loss of sight, and is in fact one of the leading worldwide causes of blindness, along with cataract, macular degeneration, and diabetic retinopathy.