NEW YORK (Reuters Health) – An intraocular lens made of a photoreactive silicone material can be adjusted using ultraviolet irradiation after being implanted following cataract removal, providing individual correction of refractive errors that remains stable for 18 months, researchers report in Ophthalmology online August 27.
“This technology may provide surgeons with a greater confidence in final refractive outcome as increasing numbers of patients expecting better uncorrected visual acuity develop cataracts,” conclude Dr. Fritz H. Hengerer and colleagues, with the Ruhr University Eye Hospital in Bochum, Germany.
The authors explain that the light-adjustable intraocular lens (Calhoun Vision, Pasadena, CA) was first presented in 2003. Since then, studies have shown that residual myopic and hyperopic errors can be corrected postoperatively using computerized ultraviolet irradiation of the device. Correction of combined sphere and astigmatism in 21 patients was reported earlier this year.
To see if spherical and cylindrical refractive errors can be similarly corrected with the device in larger numbers of patients, the team prospectively studied 122 eyes in 91 patients with significant cataract.
All patients underwent standard small-incision phacoemulsification with implantation of the light-adjustable intraocular lens. They were instructed to wear UV-blocking glasses at all times until postop adjustment was complete — one of the keys to success with the device, the authors note.
At 2 or 3 weeks after implantation, spherical and/or cylindrical adjustments were made to correct residual refractive errors using spatially profiled UV light delivered by a digital device. A final irradiation of the whole lens then “locked in” the lens power after the refractive changes had been fine tuned.
Residual errors up to 2.25 D in sphere and -2.75D in cylinder were successfully corrected with precision, the authors report. Final mean refraction achieved was 0.03 D in spherical equivalent refraction, and outcomes were stable at 18 months’ follow-up.
At the point, all patients demonstrated uncorrected visual acuity of at least 20/25, 88% had 20/20 vision, and 16% achieved 20/16, Dr. Hengerer and colleagues found.
As for safety, two eyes showed transient corneal edema and three had increased intraocular pressure postoperatively, all of which resolved within a week. Two patients experienced ongoing dry eye syndrome during follow-up.
Summing up, the authors conclude, “In our series of patients treated for residual spherical and cylindrical refractive errors, adjustments were precise and the achieved refractive outcome was stable for up to 29 months of follow-up.”