Optical Modeling and Analysis of Peripheral Optics of Contact Lenses

Background: Degraded peripheral vision has been hypothesized to be a stimulus for the development of foveal refractive error. Contact lenses have been widely used to correct central vision, but their impacts on peripheral vision are still unknown. The purpose of this study was to use optical model software to evaluate the peripheral optics of rigid gas permeable (RGP) and soft contact lenses (SCLs) in isolation. This will better assist us in understanding their peripheral optical performances on human eyes. Methods: An optical design software package (Zemax EE) was used to model peripheral optics of Menicon RGP lens and Acuvue 2 SCLs. Profiles of sphero-cylindrical power and major higher-order aberrations were computed in 10osteps out to 40o off-axis eccentricity for –3.0 D central focal power contact lens. The results of optical modeling were analyzed and compared with previously published experimental data. Results: –3.0 D RGP lenses and SCLs had –1.4 D and –2.0 D dioptric power at 40o eccentricity, respectively. The reduced dioptric power in the periphery of the analyzed contact lenses quantitatively matched with the reduced amount of hyperopic field curvature found from experimental data when these contact lenses fitted on human eyes. Cylindrical power increased to 0.3 D ~ 0.4 D at 40o eccentricity for both lens types. In addition, both contact lens types produced higher order aberrations, namely 1.2 μm coma and 0.15 μm spherical aberration at 40o eccentricity. Conclusions: Compared to SCLs, RGP lenses with equal focal power had less dioptric power in the periphery. Both RGP lenses and SCLs produced the same amount of major higher-order aberrations with increasing of the field angle. Some of these results can be used to predict and understand the peripheral optical performance of contact lenses on human eyes.