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Expert hopes 'fourth-generation' refractive procedures address limitations of LASIK, surface ablation
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NEW ORLEANS — The next generation of corneal refractive surgery is going back to the surface in an effort to resolve surgical limitations of conventional PRK, LASIK and LASEK, according to a keynote lecturer here.
Speaking at the Refractive Subspecialty Day preceding the American Academy of Ophthalmology meeting here, John Marshall, PhD, explained his belief that sub-Bowman's keratomileusis (SBK), performed with femtosecond laser technology, represents the fourth generation of corneal refractive surgery.
The three previous generations include early PRK, which has been shown to produce significant haze and delayed wound healing, LASIK, which affects the biomechanics of the cornea, and then LASEK and epi-LASEK, he said. Each of these techniques has its own limitations, he said.
"With surface ablation you want to control wound healing. With LASIK you want to control [corneal] biomechanics. Hence the suggestion of SBK, or creating a very superficial flap," Dr. Marshall said. "It is stable and, because it minimally reduces the strength of the cornea, it should remain stable as well as surface procedures do."
Dr. Marshall added that SBK will improve upon conventional LASIK by changing the edge angle of the flap to make it stronger. SBK also offers an advantage over conventional surface ablation in terms of wound healing. Early research on corneal applications of aptomers could also yield targeted wound healing control, he said.
In an effort to chronicle the limitations of conventional surgical techniques, Dr. Marshall said he and his colleagues have begun to study the effect of PRK, LASEK and LASIK at 4 to 6 weeks after surgery on human tissue by using a culture model. He said most research to date has been limited to rabbit or monkey corneas.