Optical Profiles, Visual Performance, and Modelling Optical Changes with Multifocal Contact Lenses
Purpose: Multifocal contact lenses are increasingly being prescribed for myopia control, and new lens designs are being developed and studied. This series of studies sought to understand the optical profiles of current multifocal contact lenses used for myopia control and how they affect visual performance, and to determine if optical modelling can be used to predict the effect of multifocal lenses on central and peripheral refraction. Methods: Four experiments were conducted. (1) The optical profiles of multifocal contact lenses were measured using a lens profiler. (2) Contrast sensitivity with a single vision and two multifocal contact lenses were measured and compared under photopic and mesopic conditions. (3) Wide-field optical eye models were generated using both measured and published biometry to determine how well these optical models can replicate measured central and peripheral ocular aberrations of individual eyes. (4) The optical eye models were used to predict central and peripheral refraction with a single vision and multifocal contact lens. Results: (1) The NaturalVue Multifocal has an increase in plus power closer to center and incorporates a higher maximum add compared to the Biofinity and Proclear Multifocal “D” lenses. Within each lens design, distance lens power affected add distribution. (2) The NaturalVue and Biofinity “D” contact lenses reduce distance contrast sensitivity under both photopic and mesopic conditions, but do not affect near contrast sensitivity. (3) The optical models developed were able to replicate aberrations of individual eyes, but the models generated by optimizing measured biometry data were more accurate than if optimizing using only published biometry data. (4) Optical eye models were generally able to predict central and peripheral refraction with a single vision and the Biofinity “D” multifocal contact lens to within ±0.25D of refractions measured with an aberrometer, but accuracy was reduced at an eccentricity of 20° on the nasal retina. Conclusion: Multifocal contact lenses differ in the amount and distribution of plus power based on lens design and labelled distance lens power, and these lenses cause reductions in contrast sensitivity. Optical modelling can be used to replicate aberrations of individual eyes and predict changes in peripheral refraction when a multifocal contact lens is worn.