The latest innovation in the quest for presbyopic correction may be high-repetition rate femtosecond laser non-invasive refractive index shaping. Scott MacRae, MD, reviewed the experimental results of this procedure during the Innovators' Session.
Chicago-The latest innovation in the quest for presbyopic correction may be high-repetition rate femtosecond laser non-invasive refractive index shaping (RIS). Scott MacRae, MD, reviewed the experimental results of this procedure during the Innovator’s Session.
Compared with LASIK, RIS leaves the corneal shape the same and requires about 100 times less energy than that required to create a laser flap, said Dr. MacRae, director of refractive services, Department of Ophthalmology, University of Rochester, Rochester, NY.
“The goal is to make this a minimally invasive surgery,” he said.
Femtosecond laser RIS, which works by localized accumulation of heat, does not cause endothelial, epithelial, or stromal disruption or dry eye; no special postoperative care is needed; there are no complications associated with LASIK flaps or the PRK soft contact lens falling out; and there is no need for antibiotics. This also results in less patient anxiety and greater patient acceptance of the technology.
The procedure has been tested in hydrogels, with a follow-up of about 2.5 years, and no material damage has been evident; the effect is invisible to the naked eye and the refraction pattern shows no evidence of scatter. In cats, no corneal damage was evident and there has been no regression; however, the animals have been followed for only 7 weeks.
Thus far, Dr. MacRae said that the procedure is capable of producing a refractive change of almost 3 D.
“This is an ultrafast, non-invasive procedure that changes the refractive index,” Dr. MacRae said. “The changes occur below the threshold of tissue damage. Using this technique, we expect to achieve custom vision correction of ± 3 D of sphere or astigmatism on corneas, lenses, and hydrogels. This field is moving fast and it is very exciting.”
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