By Aparna Mani, MD, PhD
MGH Medical Walk-In Unit

Eyesight develops from the initial rudimentary flickers of a newborn to the full kaleidoscope of adult vision over the first three to five years of life. Our sense of vision has such a powerful impact on how we define ourselves, our loved ones, and the world in which we live.  Yet it’s one sense that can slowly slip away as we age.  Glaucoma and cataracts are two of the most common causes of vision loss and blindness in the aging adult population. But here’s some good news:  both conditions are treatable when caught and acted on early.  I will look at both in depth, starting today with glaucoma and continuing next week with a discussion on cataracts.

Glaucoma is a disease of increased pressure in the eye leading to damage of the optic nerve – the nerve that carries all the visual information our eyes pick up to the brain where it is interpreted. Think of the eye as a fluid filled, globe-like structure with the optic nerve exiting the back like the electrical cord on a toaster or TV. If the flow of fluid in the eye is not kept in balance, increased fluid pressure can develop inside the globe leading to compression and irreversible damage to the optic nerve.  There are two main types of glaucoma:  open angle, which accounts for approximately 90% of the glaucoma in the United States, and closed or narrow angle glaucoma.

Open angle glaucoma affects about 1 in 200 people over the age of 50.  A slow, chronic process, this type of glaucoma develops over a number of years. In fact, open angle glaucoma is often called the ‘silent thief of sight’ because of its painless presentation. However, once vision loss sets in, it is progressive and irreversible. People at increased risk for glaucoma include those with a family history of the disease; African Americans and Latinos; and people with heart disease or diabetes.   The risk of developing glaucoma also increases with age for everyone, regardless of whether they have any of the above risk factors.

So if glaucoma is “silent” how can you detect changes in time for treatment to be effective? Your health care provider can detect early changes with an eye exam before noticeable vision changes develop. In addition to examining the optic nerve, they will do a formal visual field test, measure intraocular pressure (fluid pressure in the eyes), and observe for any changes in eye size and shape. Although there is no cure for glaucoma at this time, early detection and initiation of treatment can help halt or slow down the progression of the disease. Treatment may entail prescription topical eye drops, laser therapy, or surgery. If you are prescribed eye drops for glaucoma, it’s crucial you take them as directed —not keeping up with treatment is a major reason for progression to vision loss. The American Diabetes Association also recommends seeing an eye care professional (either an ophthalmologist or optometrist) for a comprehensive eye exam at least once a year.  Don’t hesitate to ask if your provider is familiar with identifying and treating glaucoma and other diabetes eye conditions.

In contrast to the quiet and slow progression of open angle glaucoma, closed angle glaucoma is a medical emergency. Closed angle glaucoma presents with sudden vision loss and pain that often prompts one to seek medical care right away. In addition, a person may experience any of these symptoms:  seeing halos around lights, nausea and vomiting, developing a red eye and/or a fixed and dilated pupil. Again, this form of glaucoma is considered a medical emergency – if you experience any of these symptoms seek medical attention immediately.