Dry Eye Risk Similar After Laser Vision Surgeries

August 31, 2012

By Amy Norton

NEW YORK (Reuters Health) Aug 29 - Two laser surgeries used to correct blurry vision have a similar chance of causing dry eyes, at least temporarily, a new study finds.

Doctors have long known that eye dryness can be a side effect of laser-assisted in situ keratomileusis (better known as LASIK) and of photorefractive keratectomy (PRK).

But the "conventional wisdom" has been that people who already have dry eyes might be better off with PRK, because it's thought to have a lower risk than LASIK.

In the new study, however, that was not the case. Patients gave similar ratings to their post-op eye dryness regardless of the procedure. And in either case, the symptoms went away within a year.

"Our study suggests that both procedures have a similar effect on postoperative dry eye findings," Dr. Edward E. Manche, a professor of ophthalmology at the Stanford University School of Medicine in California, said in an email.

"This has been my clinical experience as well," he added.

Dr. Manche's team also found that the two procedures carried a similar chance of another temporary side effect - the feeling of a having "foreign body" in the eye.

Since it was introduced in the U.S. in the 1990s, LASIK has become by far the most commonly used surgical technique for correcting nearsightedness, farsightedness and astigmatism.

Dr. Manche said LASIK accounts for about 85% of procedures, and PRK the other 15%.

PRK can be an option for people who cannot undergo LASIK because of certain factors, such as relatively thin corneas.

Both procedures improve vision by using a laser to reshape the middle layer of the cornea, the transparent membrane that domes over the pupil. The basic difference is in what happens to the outer layer of the cornea.

With LASIK, the surgeon cuts away a thin flap of tissue to gain access to the middle layer of the cornea, and once the surgery is complete the flap is replaced. With PRK, which emerged in the 1980s, there is no flap; instead the top-most layer of the cornea is removed, then naturally regenerates after surgery.

LASIK has become the far more popular choice because there is less pain after the procedure, and people gain clear vision much faster.

"PRK patients typically have two to three days of mild to moderate discomfort and take several to many weeks to achieve the same level of vision that LASIK patients achieve in the first 24 hours," Dr. Manche said.

After LASIK, he noted, people can usually drive and go back to work the next day.

The side effects seen in this study are well-known, according to Dr. Manche.

For the study reported online August 13th in Ophthalmology, researchers had 34 patients undergo LASIK in one eye and PRK in the other.

Overall, the study found, patients gave similar "dry eye" ratings to both their LASIK- and PRK-treated eyes for six months after surgery. By the one-year mark, though, they were having no more problems than they were before surgery.

The patients also rated both eyes similarly when it came to having a "gritty" or "sandy" feeling in the eye. But that problem went away within three months, with either surgery.

There was a difference, not surprisingly, when it came to vision problems. People reported more "visual fluctuation" in the PRK eye one month after surgery. But that faded with time too.

Most people do prefer LASIK over PRK, Dr. Manche noted. And the current findings suggest that PRK does not have an advantage when it comes to dry eye.

There's also the price tag, of course. In the U.S. the costs of laser vision correction vary widely. In an urban area where surgeons have a lot of overhead, LASIK might run about $2,000 to $2,500 per eye. PRK would likely be several hundred less than that.

SOURCE: http://bit.ly/RsGcS7

Ophthalmology 2012.