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Laser-cut flap may yield faster resolution of dry eye symptoms
An inverted bevel side cut acts like tongue-and-groove joinery and may lead to faster re-innervation of the corneal surface.
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 Kerry D. Solomon |
Use of a femtosecond laser in LASIK flap creation may effect quicker normalization of corneal nerves and, in turn, lead to quicker resolution of postoperative dry eye.
Dry eye after LASIK remains the most prominently reported complication of refractive surgery, with as many as one-third of patients affected. However, reports of severe dry eye after LASIK are rare, and new therapeutic options provide effective management tools.
Still, according to Kerry D. Solomon, MD, ophthalmologists should strive to create a postoperative environment that is more conducive to re-innervation, thereby minimizing the impact that dry eye can have on the healing process. An inverted bevel side cut made with the iFS femtosecond laser (Abbott Medical Optics) may create a more quickly healing flap, he said.
“The concept is, if we can better approximate that edge, we can create a kinder, gentler, friendlier environment for that nerve to re-innervate, for example, our severed flap,” Dr. Solomon said at Hawaiian Eye 2010.
Clinical impressions
The inverted bevel side cut is very similar to a tongue-and-groove joint used in woodworking, effectively drawing the flap closer to the intact cornea, according to Dr. Solomon.
“In my own experience, and I know many of us that have used the iFS for an inverted side cut, the edges themselves are really hard to find after surgery,” he said.
Previous studies have suggested that flaps in the nasal quadrant may preserve more corneal fibers, although superior hinges may function similarly. Regardless, flaps that are cut more peripherally create a broader hinge, enabling more nerve fibers to be preserved.
To that end, smaller flaps are coming into popularity because fewer corneal fiber nerves are severed. However, an elliptical flap — as the inverted side bevel cut is intended to be — may have a similar effect.
“The idea being to provide a better anastomosis so the nerve fiber layers can come back into the flap sooner to better re-innervate the cornea sooner and thinner,” Dr. Solomon said.
While cornea thickness after surgery may not have a large impact on how quickly re-innervation takes place, according to Dr. Solomon, the flap architecture, because it acts as a joint between the displaced flap and existing cornea, appears to be critical in re-innervation.
Dr. Solomon is now part of a prospective, multicenter study with Michael C. Knorz, MD, and Eric D. Donnenfeld, MD, to study the effects of flap architecture on resolution of dry eye symptoms after LASIK. While results are still pending, early returns suggest a slightly quicker return to normal corneal sensation in patients who underwent LASIK surgery with an inverted bevel side cut compared with patients who underwent LASIK with a round flap. – by Bryan Bechtel
- Kerry D. Solomon, MD, can be reached at Carolina Eyecare Physicians, 1280 Johnnie Dodds Blvd., Suite 100, Mount Pleasant, SC 29464; 843-881-3937; fax: 843-884-8587; e-mail: kerry.solomon@carolinaeyecare.com.