DEAR DR. DONOHUE: Is it possible to get wet macular degeneration from a scratch on the left eye during cataract surgery, or could it have been a cyst that caused wet macular degeneration? I am 85, and my right eye is perfect. I had cataract surgery on that eye also. — C.

ANSWER: A scratch on the eye isn’t likely to cause macular degeneration. The possibility of cataract surgery leading to macular degeneration is a remote one. More than 6,000 people who had had a cataract removed were followed for five years after the operation. Slightly more people who had the operation developed macular degeneration, dry or wet, in the operated eye than did a similar group of people who had not had an operation. This isn’t proof that cataract surgery leads to macular degeneration. The same risks that cause cataracts also cause macular degeneration. The numbers that do develop it after cataract removal are small. A cause-and-effect relationship has not been proven.

I am not clear what you mean by a cyst causing the degeneration. In what part of the eye was the cyst? I have not seen a link between cysts and macular degeneration.

The retina is the back layer of the eye, the layer that converts incoming images into nerve signals that can be transmitted to the brain so we can see. The macula is a small, round area of the retina where there’s an aggregation of cells that are essential for central vision — the kind of vision needed to read a paper, watch TV and drive. Dry macular degeneration, accounting for 85 percent to 90 percent of cases, is a wasting away of macular cells. Wet macular degeneration results from a sprouting of blood vessels in that region. Those newly formed blood vessels leak fluid and destroy macular vision. Procedures are available that can halt the progression of wet macular degeneration.

The booklet on macular degeneration explains both kinds and what is available to help those with this common eye problem. Readers can obtain a copy by writing: Dr. Donohue — No. 701, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: For quite some time, my right shoulder has hurt. I saw an orthopedic doctor, who says I have a tear of my rotator cuff. He suggested surgery. What do you think of surgery for this? I am scared that I could be worse off after the operation than I am now. I am only 44 and am quite active. — K.M.

ANSWER: The rotator cuff is a band made up of the tendons of four back muscles. The tendons wrap around the topmost part of the upper arm bone, the humerus, to keep the bone in the shoulder socket. Tears of the rotator cuff are a common problem and one of the principal causes of shoulder pain. Small tears can heal on their own. Larger tears almost always require surgical correction. All surgical procedures demand respect. Something can always go wrong. Most people who have had surgery to correct a rotator cuff tear are glad they had it. By most, I mean more than 95 percent. I would not hesitate to have this surgery.

DEAR DR. DONOHUE: Please explain what complex carbohydrates are. I see this term on all diet instructions. I don’t have a clear idea of what it means. What makes them complex, and how are they healthier than other carbs? — W.L.

ANSWER: Carbohydrates are starches and sugars. Fruits, vegetables and most grains (flours) are carbohydrates.

Complex carbohydrates are long chains of carbon molecules. Starches are complex carbohydrates. Sugars are simple carbohydrates. Complex carbohydrates don’t raise blood sugar as quickly as do simple carbohydrates, so they don’t provoke a great demand for insulin. That’s what makes them more desirable.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.