Hereditary Glaucoma

Q:  I am worried about glaucoma of the hereditary type and wonder if you could tell me more about that condition. In 1998 my older sister was diagnosed with it and all her siblings were advised to take note and be careful to have regular eye exams themselves. A few members of the family were found to have increased ocular pressure and are using eye drops to protect their sight. What worries me is that my sister was in the care of competent doctors who monitored her eye pressure but never prescribed eye drops because her pressure never was high enough until the last visit when apparently "it was too late" and only surgery offered hope of saving even one eye. Nothing worked and within about 18 months she was legally blind.

I’ve been examined regularly and the pressure in my eyes is only moderately increased so I too am having 6 month checkups and need no drops. BUT THAT SCARES ME! The sister who didn’t have many signs went blind. Is hereditary glaucoma going to cause blindness regardless of treatment? Can you prevent or even predict that?

A:  Glaucoma is a disorder of the eyes in which there is increased pressure inside the eye that can lead to impaired vision and even blindness. There are a few different types of glaucoma, but "chronic open-angle glaucoma" is the most common and usually runs in families. Although you don't mention the age of your older sister, it usually occurs after the age of 35, but has been reported even in children. The eye pressure may be only slightly elevated (22-30 mm Hg) or quite high (30-45 mm Hg). A person may notice some blurring of vision or headache or have no symptoms at all. Fortunately treatment for glaucoma, whether with eye drops, laser surgery, and/or conventional surgery, is usually effective at stopping or slowing vision loss from glaucoma.

Dale K. Heuer, MD, Chairman and Professor of Ophthalmology at the Medical College of Wisconsin, is a glaucoma expert. He told me that the fact that your sister apparently never had "high" eye pressure until her last visit is not unusual. Perhaps as many as one out of three people with glaucoma damage will not have "high" eye pressure on a single test, and one out of six may never have "high" eye pressure. The possibility of glaucoma in people with "normal" eye pressure is sometimes overlooked until later in the course of the glaucoma damage when the findings are more easily recognized. Unfortunately, in such people with "normal" eye pressure, the start of treatment may therefore be delayed and it may not be as easy to prevent more damage.

The decision of whether or not to treat someone with "high" eye pressure but without evidence of damage is based on multiple factors, one of the strongest of which is a family history of glaucoma, particularly a family history of significant visual loss from glaucoma. Dr. Heuer emphasized that it is essential for you and your sisters to convey this information about your family history to your ophthalmologists. It is certainly not inevitable that you will get glaucoma or go blind as long as you have careful and close monitoring.

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.