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First human study of new-design accommodating IOL yields positive outcomes
J Cataract Refract Surg. 2009;35(10):1671-1678.
A new accommodating IOL design provided positive visual and refractive outcomes and was well-tolerated, according to data from the first human study of the implant.
The authors reported 1-year results achieved with the NuLens accommodating IOL.
"Patients' near visual acuity improved without compromising distance visual acuity," the study authors said. "Low-vision patients gained angular magnification and could read at a distance of 10 cm."
The NuLens consists of a piston activated by the ciliary muscles that pushes a flexible silicone gel through a small hole, forming a bulge that acts as a lens. A steeper bulge correlates with greater lens strength.
The PMMA haptics of the IOL are fixated to the sulcus without sutures.
The study included 10 eyes of 10 patients with cataract and atrophic macular degeneration. Patients had a mean age of 80 years. The NuLens was implanted in the eye with the worse visual acuity. Phacoemulsification was performed through a 3.2-mm limbal incision that was enlarged to 9 mm for IOL implantation.
Data showed serious complications occurring in two patients. The rate of endothelial cell loss was high between baseline and 3 months postop.
Results showed that the patients could read a mean 3.8 lines at 6 months, up from one line before surgery. Mean corrected near distance visual acuity was slightly better than uncorrected near visual acuity at 12 months. Patients' best reading distance was at 10 cm.
IOL implantation did not affect uncorrected distance visual acuity, the authors said.
Future studies will focus on improvements in safety and performance.
The authors present a 1-year follow-up on the implantation of a “new concept” accommodating IOL called the NuLens. The NuLens contains a flexible gel housed within a small chamber. The IOL is fixated in the ciliary sulcus following phacoemulsification with the empty, collapsed capsular bag serving as a diaphragm with tension controlled by ciliary muscle contraction. The capsular diaphragm pushes against a piston in the IOL, which then forces the flexible gel to bulge through a round hole in a rigid plate. This results in a change in the anterior lens curvature, which continues to steepen with further force, thereby increasing the eye’s dioptric power up to 10 D.
The study shows by a variety of complementary measures that up to 10 D of accommodation can be achieved in 10 eyes of patients with AMD implanted with the lens over 12 months. Potential challenges to the current prototype include a 60% rate of capsular opacification, a 9 mm wound incision with induction of astigmatism, a high initial loss of corneal endothelia, limiting effects of capsular fibrosis and the “reverse mechanism” of accommodation with the current IOL model (where contraction of the ciliary muscle leads to a decrease in dioptric power of the eye and relaxation leads to an increase in dioptric power).
– Jay S. Pepose, MD
Director, Pepose
Vision Institute, Professor of Clinical Ophthalmology,
Washington
University School of Medicine, St. Louis