Borosilicate and Polyurethane as Materials for Lenses to Correct Human Presbyopia

Abstract

Start your abstract here The novel of this paper is, using gradient refractive index and spherical surfaces to design a bifocal polyurethane lens with single power instead of the previous designs, which consist of two lens with different powers to correct the vision of near and medium distances at the same time. Presbyopia occurs naturally as eyes age and the structure of the lens responsible for focusing images changes. Presbyopia treatments include corrective lenses like eyeglasses known as progressive lenses. The aims of this work were to evaluate the performance of the human eye after the treatment by using different gradient refractive glass materials. Zemax was used to design an optical system for human eye based on Liu & Brennan model. Two types of optical materials, namely, borosilicate and polyurethane, were selected to design a multifocal lens. The effects of these materials on the performance of the human eye were compared to select the best material. Three different criteria were used; minimum root mean square error, the modulation transfer function and the diffraction image analysis. Modulation transfer function and root mean square Results show that the polyurethane lens is more suitable than the borosilicate lens for correcting presbyopia. Polyurethane material lens gave a better eye performance in three distances, namely, farther, intermediate, and near than the borosilicate lens. Polyurethane lens could be used as trifocal while borosilicate work only as Bifocal lens. The Results suggested that by using only one polyurethane lens power with gradient refractive index and a variable conic for lens curvature in Zemax corrected the vision of distance, near and medium distances at one time.