Is refractive surgery for anisometropic amblyopia ready for prime time? Not yet, expert says

Las Vegas-As outlandish as it may sound now, in the future, refractive surgery may be the best treatment for severe aniso-metropia and severe bilateral amblyopia, said Evelyn A. Paysse, MD, here during a presentation at the annual meeting of the American Academy of Ophthalmology.

"Twenty years from now, we may be saying that certain types of amblyopia are surgical diseases," said Dr. Paysse, associate professor of ophthalmology and pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston.

"Is refractive surgery for anisometropic amblyopia ready for prime time? At this point, I don't think so," Dr. Paysse said. "There have only been a few studies thus far. They've all had small sample sizes, and only two have had control groups. With medium-term follow-up, it seems that excimer procedures are safe and effective, although it hasn't been proven. Randomized clinical trials are still needed to optimally evaluate their safety and effectiveness."

Quest for options

Interest in refractive surgery also has grown for more positive reasons.

"We, as ophthalmologists, also should have a continuing quest to investigate new treatment options responsibly to improve our outcomes," Dr. Paysse said.

With these various motivations under consideration, potential indications for surgical intervention include the obvious, which is failure with conventional therapy. In the future, there also may be a certain level of severe anisometropia at which conventional treatment is almost certain to fail and that could justify turning instead to refractive surgery as a first approach, Dr. Paysse said.

Although no consensus has yet been reached on the appropriate point for considering refractive surgery, she said, reasonable parameters for the amount of anisometropia might be ≥ 4 D of anisohyperopia and > 4 to 5 D of anisomyopia.

Refractive procedures that could be used to treat anisometropic amblyopia include PRK, LASIK, LASEK, clear lens extraction, phakic IOLs, and possibly intrastromal corneal implants (Intacs, Addition Technology).

Only PRK, LASIK, and LASEK, however, have been formally studied in children thus far, she said.

PRK, LASIK, and LASEK

In explaining the pros and cons with these three procedures, Dr. Paysse noted that PRK and LASEK both offer stable correction and are less invasive than LASIK, with LASEK possibly causing less pain than PRK. Minimal pain is associated with LASIK, and recovery time is faster than the other two procedures. On the negative side, PRK and LASEK both are associated occasionally with corneal haze and have similar recovery times that are lengthier than those of LASIK. LASIK has several rare but potentially devastating complications, including flap dislocation, tear or hole; keratectasia; epithelial ingrowth; and possibly endothelial cell loss.

At least 14 anisometropia refractive studies for myopia in children have been published to date involving 222 children: 88 who underwent LASIK and 134 who underwent LASEK or PRK. Individuals ranged in age from 2 to 19 years with follow-up from 12 to 48 months.