Identifying complications for laser eye surgery.
May 16, 2000 — Tired of uncomfortable contact lenses? Annoyed by the slip-sliding of glasses? You would consider laser eye surgery to correct your vision, but you’ve heard there can be distracting side effects, like seeing halos and starbursts around lights. How common are they, and which type of surgery will give you the best results with the lowest risk of side effects? A new study, in the May issue of the journal Ophthalmology, may help open your eyes.
“The side effect that the study specifically focused on were these optical symptoms that are not captured with conventional, 20/20 vision testing,” study co-author Roger Steinert, MD, tells WebMD. “When you go on the Internet, you see lots of comments on halos and glare and [double vision]. … Those kind of visual complaints, we know they occur, and we hear about them from patients. What this study looked at is whether or not there was a difference between LASIK and PRK [two popular types of laser surgery] in the frequency of these complaints.” Steinert is a consultant for Summit Technology Inc., which manufactures lasers for eye surgery.
Steinert and colleagues asked 220 patients with moderate to severe nearsightedness to fill out a questionnaire about certain side effects they experienced before and six months after undergoing one of two procedures: the older PRK or the more recently approved LASIK.
In both procedures, the surgeon uses a laser, which produces a beam of ultraviolet light in pulses that last only a few billionths of a second, to remove a microscopic amount of tissue from part of the eye called the cornea. “Basically, you are using the … laser to reshape the cornea,” Michael Gordon, MD, tells WebMD. “They are both effective, but there is more scarring and discomfort and greater delay in visual recovery associated with PRK.”
In PRK, Gordon says, the doctor removes the top layer of cells, called the epithelium. “Then you do the lasering and remodeling right on the surface of the cornea. The reason you get a delay in visual recovery and some pain is that removing the epithelial layer is like having a large scratch on the surface of your cornea that has to heal over.
“With LASIK, the surface of the cornea is essentially untouched because you make a little flap in the very upper layer of the cornea, then you do the lasering and reshaping of the cornea underneath the flap,” he says. “The flap folds back and conforms to that new shape, so you don’t have that scratch that has to heal on the surface of the cornea.” Gordon, who is in private practice at the Vision Surgery and Laser Center in San Diego, was one of the surgeons involved in the study.
The results of the study show that PRK patients experience an increase in halo and double vision, but not glare, after surgery. Patients who underwent LASIK experienced an increase in double vision, but not glare or halo. LASIK-treated patients also tended to report fewer symptoms after the procedure than those treated with PRK.
“LASIK is the most popular refractive [or vision correction] procedure worldwide right now,” Marc Michelson, MD, tells WebMD. “Most refractive surgeons are doing LASIK; a lot of people are no longer doing PRK because of the fast LASIK recovery.” Michelson, an assistant clinical professor of ophthalmology at the University of Alabama in Birmingham and the director of the Michelson Laser Vision, also was involved in the study.
“We occasionally do PRK in circumstances where we can’t do LASIK. There is nothing wrong with PRK; it is a good procedure — in fact, the cornea is not cut with PRK, [but] patients have to go through a bit more aggravation to get good results,” Michelson says.
Michelson says that because the LASIK procedure has become very popular lately, patients need to be careful when choosing a surgeon. “It is critical that patients seek out someone with experience and a long history of good outcomes,” he says. “A lot of doctors are learning the procedure — that’s not to say that someone learning the procedure doesn’t have the capability of doing good — but it’s ‘Buyer Beware!'” An experienced surgeon can oftentimes fix the side effects as well, he says.
“It is somewhat reassuring, in that the study shows that we are going in the right direction by doing LASIK rather than PRK,” says Steinert, who’s also an assistant clinical professor at Harvard Medical School and a member of Ophthalmic Consults of Boston. He adds it’s a good reminder that some patients do experience these side effects. “Although the vast majority of patients consider these side effects to be tolerable, they may experience them, and it is not something that can be predicted or avoided regardless of the skill of the surgeon.”
PRK and LASIK are two popular eye surgeries that can correct vision, but there may be some side effects.
Patients who undergo PRK may see halos or have double vision, while those who undergo LASIK may experience double vision.
LASIK is a newer procedure with a shorter recovery period and is less likely to cause any side effects, compared to PRK.