Question: Help! I remember reading in your column about seeing zigzag lines. It's happening to me, and more frequently of late. Please write on this again to put my mind at rest.

- Mrs. G.T.

Answer: You are having an important sign, one that can reflect a wide range of problems, from the harmless to the serious.

Sometimes, zigzag vision occurs as a prelude to migraine headaches, the so-called migraine "aura." You don't mention headache, but not having pain doesn't foreclose the possibility. You can have migraine aura without the actual headache.

I find your reference to the episodes' increased frequency troubling. That can indicate a worsening of whatever lies behind them.

Temporal arteritis is another possibility that might produce a variety of visual symptoms. Inflammation of the cranial vessels also can pose a threat to sight if unchecked.

Vision irregularities can mean a retinal tear. The retina is the layer of light-sensitive cells at the back of eyeball. Damage there might compromise vision.

You need prompt attention. See an eye doctor right away.

Question: We are three senior ladies. We have been comparing notes. We all seem to be a few inches shorter than when we were younger. We want to know if this means automatically that we have osteoporosis. Or is getting shorter a normal process, like getting gray hair?

- Sue, Dot and Ellen

Answer: We lose a bit less than half an inch for every 10 years after age 40.

Part of that loss can be accounted for in the natural flattening of our feet. The rest of the loss is in shrinkage and from a collapse and compression of the vertebral disks that make up the spine.

Bone thinning of osteoporosis is a major cause of height loss.

I'd bet that at least one of your group would benefit from osteoporosis treatment.

You can find an in-depth discussion of osteoporosis in my 23rd pamphlet. For a copy, send $3 and a self-addressed, stamped (55 cents) No. 10 envelope to: Dr. Donohue - No. 23, Box 5539, Riverton, NJ 08077-5539.

Question: I suspect my son is experimenting with marijuana. I would like to inform him of the dangers, both in the short term and long term. Please list some of the bad effects.

- S.M.

Answer: The short-term adverse effects of marijuana smoking can be many and varied.

It can affect the way our eyes track objects. It can produce a distortion in perception and can prompt foolish and dangerous misadventures. Physiologically, marijuana increases the heart rate, dries out mouth tissues, causes tremors, disrupts coordination and disturbs sleep patterns.

Long-term marijuana use can produce bronchitis. Some say marijuana is more of an air-passage irritant than tobacco.

So, concern about use, certainly heavy chronic use, has some sound rationale. From long experience with marijuana and after numerous studies, authorities now say it is anything but the harmless substance some colleagues once believed it to be.

Question: I've been considering having electrolysis done but have a few concerns. Sometimes people rush into such things without bothering to find out possible problems. How common is electrolysis? Can you get infected? What can you do to avoid infection? Is there any chance of getting the AIDS virus? Does electrolysis enlarge pores?

- K.U.

Answer: I congratulate you for having the prescience to look before you leap.

I don't mean that as a rap against the electrolysis specialists out there. Electrolysis is a time-honored method for removal of unwanted hair.

Electrolysis is pretty common. I used to hear periodically from one or another professional member organization. I trust I will again after this reference, letting us know just how common a procedure it is.

Sure you can get an infection, just as you can whenever you invade the skin. But if you select your electrologist carefully, that's not likely. Be sure the technician operates in a clean clinical area, as most do. And be sure sterile instruments and disposable material are used.

If your operator follows professional and governmental guidelines, the chance of becoming infected is practically nonexistent. You will not expose yourself to the AIDS virus or any other, so long as the operator adheres to prescribed standards. Inquire to be sure your operator has the appropriate educational background, proper credentials and approval of local or state boards of control. In 28 states, electrolysis operators must be licensed.

The procedure does not enlarge pores.

For C.I.: Interferon Alpha is a drug that is injected under the skin. It is used to control the hepatitis C virus. It is given when blood tests indicate that liver damage is ongoing.

I'm not surprised that you have found it difficult to locate hepatitis C in your older medical books. Try looking under "non-A, non-B hepatitis," which is what hepatitis C used to be called.

I can't tell you much more about your condition, except to note that sexual transmission, while possible, is not the most likely method. Drug-paraphernalia contamination is a cause, although not in your case.

For a detailed report on hepatitis, send $3 and a self-addressed, stamped (55 cents) No. 10 envelope to Dr. Donohue - SR145, Box 5539, Riverton, NJ 08077-5539.