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A hydrogel corneal inlay designed to treat presbyopia seems, based on early clinical results, to improve near vision markedly without significant safety concerns.
When in place, the inlay creates a steepened region in the center of the cornea to improve near vision in patients with presbyopia. Dr. Slade described the implant as "very small, nice material, and quiet in the eye."
"The surgery to implant this device is very simple," said Dr. Slade, in private practice in Houston. "An 8.5-mm, 160-µm flap is created using a femtosecond laser. There is sufficient tissue remaining for a concurrent LASIK procedure if that is desired. After lifting the flap, the 2-mm implant is put in place, and the flap is replaced. This procedure takes no longer than a standard LASIK procedure."
The U.S. investigational device exemption results from 29 patients who had been followed for 6 months postoperatively, Dr. Slade noted. The study protocol required a near add, uncorrected near visual acuity below 20/40, and a spherical equivalent of plano.
"Ninety percent of patients were able to see 20/32 or better, and 76% of eyes still maintained excellent distance visual acuity," Dr. Slade said. "This is really what this is all about: how much distance vision is sacrificed compared [with] what is gained in near vision.
"The results indicated just how nicely this procedure works," he said. "Functionally, using both eyes 97% of patients have 20/20 or better visual acuity at distance and near. Intermediate vision is also excellent."
All subjects had stable refractions (i.e., they met the FDA metric of 0.5 D) when the results at 3 and 6 months after implantation were compared. One patient lost two lines of best-corrected visual acuity, one developed elevated IOP resulting from steroids, and one patient had a myocardial infarction.
In a study of the accommodation in monkey eyes, Dr. Slade cited a study performed by Adrian Glasser, PhD, in which he reported that "the change in the optical power is pronounced and uniform over the central 3 mm but decreases rapidly beyond that in the periphery of the lens. This implant is a near add that mimics that."
"The implant is removable, but the effect is not reversible," Dr. Slade said. "The beauty of keratophakia is that it is easily centered and removable. Early outcomes of this trial lens support that the inlay offers marked improvement in near vision without significant safety concerns."
FYIStephen Slade, MDE-mail: firstname.lastname@example.org
Dr. Slade is a consultant for ReVision Optics.