FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

MIDDLE AGE MEANS "PRESBYOPIA" AND READING GLASSES

Question: I'm a dairy farmer who has started having prblems with my eyes for the first time at age 42. In your last column, you explained why vitamins and mineral supplements wouldn't help. Isn't there anything I can do to help my eyes? Do I just need to give up and wear glasses?

Answer: Since you haven't needed glasses before now, and your eye doctor said that everyone develops this type of trouble, it is likely that you are suffering from a condition called presbyopia, or in plain English "old eyes." You see, the human body was only designed to work well for about 40 years. Upon moving into the fourth decade, most body systems lose some of their previous youthful effectiveness. The hair thins and turns gray, joints "creak," and it becomes difficult to see objects up close. Let me explain a bit about the way the eye works to help you understand why close objects become difficult to see while distant ones remain in sharp focus.

I'm sure that you remember from health class that the eye works much like a camera. One of these similarities is the focusing system that utilizes two eye structures the cornea and the lens. The cornea is the slightly curved, transparent outer layer of the eye through which we see. It actually serves as the primary or "strongest" lens. The structure called the "lens" is located deeper within the eye, and its contribution is that it is adjustable in its strength. Our eye's two-element, fully automatic focusing system operates much like my new computerized 35mm camera. But unlike my camera, you can't hear the eye adjust its lens.

As in most cameras, only one lens moves or adjusts. While the cornea doesn't adjust, muscles within the eye pull on the lens in a way that causes it to become a more powerful magnifying glass when something close is viewed. The muscles relax to let distant objects be in sharp focus. This process happens so rapidly and accurately that one rarely notices it until it stops working properly.

An image is focused on the retina in the back of your eye just as picture image is focused on your camera's film. Close objects require a different focus than do distant objects.

In their fourth decade most people start holding the newspaper a little farther away and often using brighter light to read by. Ultimately, just as you eventually will, he or she acquiesces to wearing reading glasses.

Your near vision is getting worse because the lens within the eye becomes stiff with age. Your eye muscles are no longer able to reshape the lens to bring close objects into focus.

These changes do not occur overnight. Early on, reading is only difficult shortly after rising and later in the day as the eyes gets tired. Perhaps this is where you are now. A year or two later, reading is a strain even in the mid-day hours. This process continues slowly until some time in the fifth decade when the lens usually becomes so stiff that it loses all ability to accommodate. Then trifocals or progressive lenses are necessary to clearly see up close, at arm's length and at a distance.

Fortunately, you have lived long enough to have this "natural" process, presbyopia. There are no treatments that turn back the hands of time. Put on your glasses and see again!

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.