You have undoubtedly been exposed to the barrage of advertising, media blitz and medical hype concerning radial keratotomy (RK), an operation being offered for the treatment of myopia.

If you are nearsighted, you may be considering it for yourself. It is said that more than 100,000 Americans already have had this surgery. To make an intelligent decision, there are a number of facts you should know.

There are major risks as well as a possible benefit involved in the surgery. Not recognizing the risks could have disastrous consequences.

The process of balancing risks against benefits is called risk-benefit analysis. For example, if you jump from the fourth floor of burning building because there is no other escape, you accept the risk of jumping because the alternative is incineration. If you jump from the same room to win a $5 wager, you have done a very foolish thing.

If you undergo radial keratotomy, are you jumping to save your life or to win a trivial wager?

RK consists of making eight to 16 small incisions in the cornea. As the incisions scar, the eye becomes more flat. Myopia is caused by an eye that is too spherical; the surgery may improve nearsightedness so that glasses or contact lenses are no longer required. For the overwhelming number of subjects, the potential benefit is largely cosmetic -- no more glasses or contact lenses.

What are the risks? First of all, the surgery may not work. In some patients (perhaps as high as 20 percent), surgical results are unfavorable. Myopia may not be cured. In fact, vision after the operation may be worse than before. The patient may have difficulty with glare, with decreased visual acuity, with night vision or with intermediate vision. The ophthalmologist cannot predict for which patients the surgery will fail.

It has been reported in one study that several years after surgery one third of patients develop progressive hyperopia (farsightedness). This complication may progress rapidly in some patients so that frequent changes of prescriptions for glasses will be required. This problem is bad enough on relatively young people, but may become exaggerated as you age. After the age of 40 or 50, most of us develop presbyopia, or difficulty with accommodation of near vision as a result of normal aging. The problem of farsightness may become worse in those who have undergone RK.

The most frightening potential risk of all will hang over your head indefinitely. A variation of this form of surgery was originally performed by a Japanese surgeon. After a number of years, essentially all of his patients became blind. The cornea is a fragile structure and apparently the irreversible damage produced by that operation injured it sufficiently to cause corneal clouding and blindness. To be sure, his operation was more extensive than the one being offered now. But it is possible that RK some years down the road could result in mass blindness.

Given the substantial nature of the risks, you might think a sensible response would be to declare a moratorium on the surgery. At least to stop it until it was certain that the benefits outweighed the risks. Nothing of the kind is likely to happen.

One reason involves the clearest benefit of the surgery: money. The major beneficiary is the surgeon. This 15-minute outpatient surgical procedure costs between $2,000 and $3,000 in most places. The surgeons have the gall to charge the patient per eye, which should tell you something.

Who will protect you if the risks are as extreme as I have outlined?

You cannot depend on individual ophthalmologists. RK has been labeled as a medical controversy. Proponents of RK argue that those reporting bad results used the wrong technique.

Nor can you depend on the professional organization of ophthalmologists, the American Academy of Ophthalmology, which has labeled the procedure "experimental," presumably to warn the public of potential risks.

And the government won't protect you, because many of the specific details of medical practice, including RK, are not subject to government regulation.

Who can you turn to for protection? In a real sense, you as an individual patient must protect yourself.

If you have read this, you have taken the first step. May I suggest another? When you enter the surgeon's office, he will hand you a form to sign. The form is called an informed consent form and is more for his own protection than yours.

Clip out or copy the following "guarantee" form and ask him to sign it before you undergo surgery:

I (ophthalmologist's name) guarantee that if you (your name) undergo radial keratotomy:

1. Your nearsightedness will improve.

2. You will not develop additional problems with vision such as failure of the surgery to improve your vision, troublesome nighttime vision, troubles with intermediate vision and troublesome glare.

3. You will not develop farsightedness.

4. As you age and become presbyopic, the surgery will not complicate your eye problems.

5. You will not develop an infection of the eye as a result of the surgery.

6. Should infection develop, you will not require removal of the infected eye.

7. You will not develop long-term problems with abnormal corneal function, which might result in blindness or severe visual impairment.

Should any or all of these complications occur, I accept full legal and financial responsibility.

His reaction will be more instructive than any advice from me.