Regular eye exams can catch glaucoma early

Q: My mother has open-angle glaucoma. This increases my risk for glaucoma. Can I do anything to reduce that risk?

A: You're right to think that your risk is increased. Because your mother has the condition, your chance of getting it is at least double that of most people you know. That doesn't mean you will get glaucoma; it just means you inherit a risk, and therefore need to be particularly careful.

Glaucoma refers to a group of eye diseases that cause vision loss by damaging the optic nerve. The optic nerve relays visual information from the eye to the brain. In order to see, we need all three: the eye, the optic nerve and the brain. (Of course, it's a little more complicated than that.)

Normally, a liquid called aqueous humor fills the front part of the eye. From there, the liquid passes through a sievelike system of tissues and drains out of the eye to be absorbed into surrounding blood vessels. As more aqueous humor is produced, excess fluid is eliminated. This keeps a healthy balance of pressure in the eye.

In glaucoma, the drainage system breaks down, slowing or blocking fluid flowing out of the eye. The fluid backs up in the eye and internal pressure rises. This, in turn, stresses the optic nerve. If the pressure continues, nerve fibers begin to die and vision starts to fade. The pressure also can slow the flow of blood through tiny blood vessels that feed the retina and optic nerve. This can cause further vision loss.

Open-angle glaucoma is the most common form of glaucoma. In it, the angle through which fluid drains from the eye remains open, but the aqueous humor drains out too slowly. This leads to fluid backup and rising pressure.

There is no way to prevent glaucoma, and early glaucoma typically causes no noticeable symptoms. But comprehensive eye exams can catch glaucoma early. This provides an opportunity to begin treatment before it causes irreversible vision loss that can lead to blindness.

Anyone at high risk for glaucoma - as you are because of your family history - should have regular eye exams. That means every one to three years between the ages of 40 and 54; every one to two years between the ages of 55 and 64; and every six to 12 months from age 65 onward.

Drugs to lower pressure in the eye are the main treatment. If medication is not effective, your eye doctor may recommend laser treatment or eye surgery to improve the eye's natural drainage or to create a new route for fluid to drain.

Once you have glaucoma, your best bet for preventing vision loss is taking medications as directed. Even if a person's eye pressure is still in the normal range, further lowering it can prevent optic nerve damage from getting worse.

• Dr. Anthony Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.