Innovations move refractive surgery along path back to the surface

November 9, 2007

As the evolution in refractive surgery continues, surgeons can expect to see the journey continuing back to the surface - aided by new strategies to improve the outcomes of sub-Bowman's keratomileusis (SBK) and PRK, said John Marshall, PhD, in his keynote address at Refractive Surgery Day.

As the evolution in refractive surgery continues, surgeons can expect to see the journey continuingback to the surface-aided by new strategies to improve the outcomes of sub-Bowman'skeratomileusis (SBK) and PRK, said John Marshall, PhD, in his keynote address at Refractive Surgery SubspecialtyDay.

SBK, involving creation of a very superficial flap using a femtosecond laser, was introduced toprovide the benefits of both LASIK and PRK. Since creation of the very thin flap minimally reducesthe strength of the cornea, SBK is expected to provide the biomechanical stability of PRK, but likeLASIK, without the pain and haze that are sequelae of post-PRK wound healing, he said.

Looking to the future, Dr. Marshall suggested biomechanical stability after SBK can be furtherimproved by changing the edge angle of the flap.

"Making the edge angle more oblique makes the flap stronger," said Dr. Marshall, head of thedepartment of ophthalmology, Kings College, London.

Recognizing that wound healing is a limiting variable for PRK, Dr. Marshall suggested the surfaceablation procedure will be improved by pharmacologic modulation of that process. Possible strategiesinclude use of the simple sugar, mannose 6-phosphate, and aptamer technology.

"Studies from our group show that mannose 6-phosphate, which blocks receptor sites on keratocytes, iseffective in preventing haze in animal models," Dr. Marshall said. "In addition, we have found thataptamers selectively differentiating between activated and latent keratocytes can be used fortargeted wound healing control."

Dr. Marshall is featured in Ophthalmology Times' AAO Podcast Series. To listen to an interview with Dr. Marshall, click here.