Tweet

1. See the world in grey: Reshaping the eye with a laser can cause some distortion in the eye`s optics that decreases what ophthalmologists call `contrast sensitivity`: the difference between dark and light narrows. It is roughly analogous to a photograph that is in focus but too grey. Sometimes the loss of contrast sensitivity is described as adding a ghostliness or fuzziness to vision. The reason for this optical distortion following a LASIK and other laser operations is not yet known. Nor is it known exactly how many people who undergo LASIK experience a loss of contrast sensitivity. The fact remains that the loss of contrast sensitivity seems to be much more common in people whose vision was especially bad even before the LASIK surgery.
2. Of halos and starbursts: While the recovery period from LASIK is remarkably short, 30%-40% of people see halos or `starbursts` around bright lights for several months.
   
   This effect seems to be caused by the edge between the treated and the untreated part of the cornea bending and distorting the way light hits the eye. It is most obvious at night, when the pupil dilates and this edge falls right into view. For this reason, people with exceptionally large pupils should not opt for LASIK surgery.
   
   The starburst effect usually goes away, but for people with extra-large pupils it can remain a permanent problem.
3. You may not be the right gal (or guy): Despite its increasing popularity, LASIK is not for everyone. People with extra-thin corneas are not good candidates because the surgeon needs enough tissue to work with. The thickness of the cornea is not necessarily related to vision. So the only way of knowing if your corneas are thick enough is to have them measured by an ophthalmologist. Some ophthalmologists also turn away people with rheumatoid arthritis and lupus because they can have problems with dry eyes and recovery from LASIK involves some drying out of the eyes. People with diabetes also may not be ideal LASIK candidates because the outermost layer of their cornea, the epithelium, is thin and they have decreased corneal sensation.

Finally, people who are candidates for a cataract surgery shouldn`t choose LASIK. A cataract is a cloudy lens; operating on cataracts involves taking out the clouded lens and replacing it with a new plastic or silicon version. Artificial lens implants can correct nearsightedness or farsightedness just as well as LASIK. So, there is no point in having both the procedures.