Lens corrects myopic astigmatism

February 15, 2011

Results from 6 months of follow-up in a prospective, multicenter European clinical trial show that the toric version of the foldable iris-fixated phakic IOL provides stable, effective correction of myopic astigmatism with a high safety index.

"Except for the need for preoperative axis marking to assure the implant is properly aligned and fixated, the surgical procedure for implanting the toric phakic IOL is identical to that used for the foldable myopic model, and the early results show that the safety and efficacy index profiles are also similar for the toric and spherical versions," Dr. Nuijts said. "However, longer follow-up is needed to assess efficacy and safety and especially to identify a cause for cases of deposition of pigment and nonpigment cells on the optic surface."

Dr. Nuijts is associate professor of ophthalmology, University Hospital Maastricht, The Netherlands. He discussed the outcomes on behalf of his co-author, Muriël Doors, MD, University Hospital Maastricht, and the European Artiflex Toric Study Group.

"At a minimum, the implantation can be performed through a 3.2-mm incision, although I prefer 3.4 mm," Dr. Nuijts said.

The European multicenter clinical trial, which was sponsored by Ophtec, included 117 eyes with a mean sphere of –6.5 D, mean cylinder of –2.2 D, and mean SE of –7.7 D. The patients had a mean age of about 37 years, and about two-thirds were women. About two-thirds of the eyes were seen at 6 months.

Excellent refractive and visual acuity results were achieved by 1 day after surgery and these outcomes were stable throughout the 6 months of available follow-up. Mean SE was –0.07 D on postop day 1 and was –0.04 D at 6 months when achieved SE was within 0.5 D of target in 77% of eyes and within 1 D in 97% of eyes. Absolute cylinder was reduced 85% from baseline at 6 months to a mean of 0.34 D.

"The double-angle plot from vector analysis of astigmatism shows a wide spread of data points around the mean preoperatively but a very tight distribution at 6 months after the IOL implantation," Dr. Nuijts said.

Early data

At 6 months, uncorrected visual acuity (UCVA) was 20/20 or better in 59% of eyes. The efficacy index (postop UCVA/preop best-corrected visual acuity [BCVA]) was 1.05 and the safety index (postop BCVA/preop BCVA) was 1.15. Best spectacle-corrected visual acuity was improved by 2 lines from the preoperative level in 16.3% of eyes, and 2.5% of eyes had a loss of 2 lines, which was related to the formation of synechiae, according to Dr. Nuijts.

"Mean IOP was not elevated significantly in relation to the preoperative measurement at any of the follow-up visits," he said. "The most significant complications involved deposition of pigmented and nonpigmented cells that was noted on 13% and 11% of IOLs, respectively, at 6 months."

At 6 months, there was a 9.6% incidence of mild to moderate glare complaints and a 4.4% incidence of mild halo complaints. Measurements of endothelial cell density showed a mean loss of 4.7% at 6 months.

"These data are much too early to draw any definite conclusions about endothelial safety," Dr. Nuijts concluded.

FYI

Rudy M. Nuijts, MD, PhD
E-mail: rudy.nuijts@mumc.nl

The toric iris-fixated phakic IOL is not FDA approved. Dr. Nuijts receives research funding from Alcon Laboratories and Ophtec.