I've been told the thickness of my cornea is at a borderline level and that I am not a good candidate for Lasik. Is cornea thickness still a factor? -- Christine Kosmowski, Battle Creek, Mich.
Corneal thickness is definitely very important, but it's not the be-all and end-all. The shape is very important as well. At the UCLA Laser Refractive Center, we are using a new device during our screening process that tests the strength of the cornea by pushing on the cornea with a very short puff of air. All of these components of the screening examination -- thickness, shape and strength -- are extremely important. You could have normal thickness, but the shape is irregular and so you're not a great candidate. But if the cornea is thin, regardless of the shape, I'm not going to do Lasik. Those with thin corneas typically are a candidate for PRK (photorefractive keratotomy), which is the same laser shaping, but without the flap. PRK has excellent long-term results but the post-operative recovery period is longer than with LASIK.
My eye doctor is concerned that Lasik has not been around long enough for us to know the magnitude of any side effects. How likely are side effects? -- Vickie Choitz, Somerville, Mass.
Dry eyes are the most common side effect, typically lasting three to six months after the surgery. We know that dry eyes are more common in women than men, and it's more common in postmenopausal women than in premenopausal women. But there are very effective treatments, including a medicated eye drop called Restasis and oral supplements called BioTears.
The other side effect you will hear about is quality of vision at night, such as halos and glares off of lights. This used to be a problem, especially in higher corrections. In my experience at the UCLA Laser Refractive Center, it's much less of an issue with custom wavefront Lasik now.
How widespread is wavefront-guided Lasik and all-laser Lasik? -- Jeffrey Martens, Topeka, Kan.
The most recent numbers I have seen are about 15 percent of Lasik cases use laser flap creation (called intralase) instead of a blade, and that number is going up. The intralase system is expensive, so laser centers have to perform a fairly high volume of surgery to make that work financially, but there's more and more evidence that it is very useful and provides benefits in terms of safety and predictability of results. Wavefront-guided Lasik is on the order of 40 to 50 percent and also going up.
Does Lasik surgery successfully correct severe astigmatism? -- John Barada, Reno, Nev.
Yes, with limitations. Most of the FDA lasers are approved for up to about 4 diopters of astigmatism correction, which covers 98 percent of the population. Some astigmatism irregularities indicate a problem with the cornea, which indicates you're not a great candidate for refractive surgery.
