Word: corneas
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Thank you for the wonderfully balanced article on laser surgery to reshape the cornea and help improve vision [HEALTH, Oct. 11]. As a cornea-trained ophthalmologist who performs LASIK, I am always concerned that patients will have unreasonably high expectations because they have heard only the "good side" of the surgery. Although the results are impressive, we are currently not able to achieve more than a 60% to 70% portion of 20/20 vision because of the range of biological variation in the general population. Not all people correct predictably after a given amount of applied laser energy. Remember, the goal...
Nearly everyone who undergoes LASIK experiences at least some glare and halos, usually at night or under fluorescent lights. This occurs because the pupil widens in dim light, allowing incoming light to pass through both the corrected and uncorrected sections of the cornea, creating either a blinding or a hazy image. The problems usually diminish within six months. The best guess is that 5% of patients continue to be substantially bothered by glare and halos over the long term...
...dark often have the biggest problems. An equally critical factor, however, is the amount of correction you need, measured in negative (-) diopters for nearsightedness and positive (+) diopters for farsightedness. The greater your correction, the more abrupt the transition zone between the sculpted and unsculpted portion of the cornea, and the greater the risk of troublesome glare and halos...
Another big advance in the works could provide nearly all patients with better than 20/20 vision. Today's lasers, and the computer programs that run them, assume all corneas are more or less spherical. Scientists are developing instruments that will map the entire surface of the cornea and make point-by-point alterations to smooth out individual aberrations. Such carefully customized reshaping of the cornea could make astounding improvements in vision more of a sure thing...
...FIND OUT HOW MUCH LASIK TRAINING YOUR DOCTOR HAS. Some ophthalmologists apparently start zapping corneas after little more than a weekend seminar. That might be enough preparation for a surgeon who is already skilled, but you may decide to select a more experienced doctor, such as a cornea specialist who has completed a year or two of additional training. Early studies also showed that the complication rates for individual surgeons underwent two significant drops, after 300 and 600 procedures. Proponents will tell you that LASIK training and technology are much better now and that today's doctors are perfectly proficient...