Effect of field of view and iris pupil diameter on the quality of retinal image with allyl carbonate (CR-39) polymer contact lenses

Abstract

Contact lenses are manufactured from high-grade plastic polymers and prescribed by specialists to treat myopia, hyperopia, astigmatism and presbyopia. Some people opt to wear contact lenses directly on the cornea for aesthetic reasons. The formed image is mainly focused on the retina. Manufacturers are constantly searching for and developing optimal materials for contact lenses to satisfy patients and practitioners in terms of the standard optical characteristics (i.e. Refractive index, abbe number, light reflectance and light transmittance). In this study, allyl carbonate, which is commonly known as CR-39, was tested as the polymer material for contact lenses. The CR-39 polymer material data (refractive index, 1.49; density, 1.32; Abbe number, (58-59) were used in establishing the Liou & Brennan model. The effect of iris, pupil size and the field of view (F.O.V.) on the retinal image was evaluated and analyzed using Zemax-EE software (2005), The modulation transfer function (MTF), point spread function (PSF), blur spot size (RMS), encircled energy (EE) and the type and amount of aberrations, are used as a criteria to analysis the retinal image degradation. The results show that the CR-39 polymer material has good optical properties, which render it a recommended material for ophthalmic contact lenses.