New Material for an Adjustable Intraocular Lens

Abstract

Abstract: : Purpose: Most patients require spectacles for optimal vision post-operatively after cataract surgery. The purpose of this work is to develop a photosensitive silicone material for intraocular lenses whose power can be adjusted non-invasively in-situ after cataract surgery to provide patients with spectacle free vision. Methods: A silicone intraocular lens material was developed incorporating a photopolymerizable silicone system comprised of a macromer, photoinitiator and UV absorber to achieve an optical power adjustment through shape change of the lens material. Photopolymerization of the macromer component in the cured lens was accomplished by irradiation in the near UV range. The photoinitiator and UV absorber concentrations were optimized to allow for efficient photoinitiation at safe levels of UV exposure while maintaining the UV absorption properties of the natural lens. Lenses molded with this material were tested for biocompatibility using a rabbit model, and power adjustment using an interferometric technique. Results: Light Adjustable Intraocular Lenses (LAL^TM) molded from silicone material incorporating the photosensitive silicone system demonstrated optical power adjustments in the range of ± 2 diopters upon irradiation with UV light of controlled wavelength, intensity and pattern. Power adjustment was achieved by polymerizing the center of the lens (for hyperopia) or the edges of the lens (for myopia). The unreacted macromer in the unirradiated zones diffused into the polymerized region to produce a shape change of the lens corresponding to the degree of polymerization induced. The material showed no toxicity and is fully biocompatible. Conclusion: A photosensitive silicone material has been developed for the Light Adjustable Intraocular Lens (LAL^TM) that can be adjusted post-operatively ± 2 diopters for the correction of myopia, hyperopia and astigmatism. This technology can serve as a platform for the further development of multifocal, accommodating and phakic IOLs and with the use of wavefront technology to correct for higher order aberrations.

Keywords: cataract • refractive surgery: optical quality • visual acuity