Glaucoma is indeed a potentially blinding disease. Worldwide, it is the second most common cause for irreversible blindness. However, with early diagnosis and modern treatment, blindness is very uncommon.
What does blindness mean?
Blindness means different things to different people. To the average person, blindness means the absence of all vision. However, the U.S. government defines blindness as severe loss of vision which limits mobility and other activities. The official definition is visual acuity in the better of the two eyes that cannot be corrected by lenses to better than 20/200 or loss of peripheral vision to less than 20 degrees. While “legal” blindness certainly restricts visual capability, it is far from the total blackness that most people imagine.
What are the actual chances that a patient with glaucoma will reach “legal” blindness?
In general, from the best data in developed countries of the world, the risk of reaching that level of visual loss with a diagnosis of glaucoma is about 5%. In many of those people, the visual loss is compounded by the added presence of other eye conditions such as macular degeneration.
Each person’s actual risk will depend on how far advanced the glaucoma is when first diagnosed. The more advanced the glaucoma, the greater the risk. Therefore, it is critical to get regular eye examinations before symptoms appear so that, if glaucoma does develop, it is caught early when treatment is most effective at preventing vision loss. Of course, regular follow up and adherence to prescribed treatment are also critical in slowing or stopping progression.
New and improved treatments should make severe vision loss even less likely. Although some eyes seem to be resistant to all modalities of treatment, for the vast majority of patients with glaucoma, adherence to treatment and appropriate monitoring will keep them from becoming blind by any definition.
Posted on May 3, 2021; Reviewed on March 23, 2022
Robert L. Stamper, MD
Robert L. Stamper, MD is a Distinguished Professor of Clinical Ophthalmology and Director Emeritus of the Glaucoma Service at University of California, San Francisco.