By Fred Gebhart
SAN FRANCISCO -- October 29, 2009 -- An investigational phakic intraocular lens (IOL) has provided significantly improved vision and high levels of satisfaction in myopic patients during a phase 3 trial presented at the 2009 Joint Meeting of the American Association of Ophthalmology and Pan-American Association of Ophthalmology (AAO-PAAO).
"We've got great outcomes, uncorrected 20/25 vision or better in 90% of patients," said coauthor Joseph Biber, MD, Cincinnati Eye Institute, University of Cincinnati, Cincinnati, Ohio, speaking here on October 26. "And 98% of our patients say they would have this procedure again. One year out, we feel comfortable saying that this is a great lens for high myopes."
Researchers implanted the phakic angle-supported IOL in 419 adult patients across 18 clinical sites in the United States. All of the patients had stable moderate-to-high myopia -- defined as -6.0 dioptre (D) to -16.5 D -- with refraction unchanged by more than 0.5 D in the past 12 months. Lenses were sized using anterior chamber ocular coherence tomography (OCT) using a maximum of 4 angle measurements (0, 45, 90, and 135 degrees) for selection.
The mean spherical equivalent at baseline was -9.65 D, Dr. Biber reported. After 1 year, the mean had improved to -0.16 D. Uncorrected visual acuity was 20/20 or better for 79.1% of patients, 20/25 or better for 90.8%, 20/32 or better for 96.6%, and 20/40 or better for 98.8%. Best corrected visual acuity was 20/16 or better for 97.1%, 20/20 for 99.3%, 20/25 for 99.8%, and at least 20/32 for 100% of patients.
Predictability of refraction was also good, within 0.5 D of target for 85.7% of patients and within 1 D for 97.8%. Slightly over one-third of patients (37.4%) had no change in visual acuity, but 44% had a 1-line gain, 15.3% had a 2-line gain, and 2.7% gained more than 2 lines.
Patients reported very mild visual symptoms preoperatively, Dr. Biber said. Postoperative symptoms were slightly reduced. Complaints of glare fell from 1.46% to 0.89%, and night-vision problems declined from 1.21% to 0.81%. There was essentially no change in halos (0.97% preoperatively and 0.96% postoperatively).
Researchers reported minimal endothelial density changes. Central cell density compared to baseline was -0.98 at 6 months and 0.81 at 12 months. Peripheral density was -0.58 at 6 months and -1.39 at 12 months. There was essentially no change in the percentage of hexagonality in either the central or peripheral regions. The coefficient of variation, a measure of difference in cell sizes, improved minimally, from 33.29 to 32.14 in the central region and from 34.27 to 32.04 in the peripheral region.
Adverse event rates were low, with just 0.2% increased intraocular pressure requiring treatment more than 1 month post operatively, 0.2% IOL replacement, 0.5% haze, 0.2% loss of best spectacle-corrected visual acuity, and 0.5% synechia. Researchers reported 0.5% cataract formation that was not lens-related, and there were no reports of pupil ovalisation.
"This is a very fast and easy device to implant," Dr. Biber said, "and easy to replace if it becomes necessary. It is one more viable option to laser vision correction."
A similar trial in Europe published earlier this year showed good outcomes, Dr. Biber added.
[Presentation title: Clinical Outcomes of the AcrySof Phakic Angle-Supported IOL in a Phase 3 US Clinical Trial. Abstract PO548]
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