Abstract
Purpose :
Multifocal optics are now commonly employed to control progression of myopia in children. This simulation study explores their impact on the visual performance of children.
Methods :
Retinal images were simulated for models that included the complex interaction between increasing angular size of real-world stimuli, decreasing pupil size, changing higher order aberrations, and varying accommodative errors as the stimuli approach the observer. Model parameters were derived from published data and results from our own lab for viewing distances of 4m, 1m, 33cm and 20cm. Through focus image quality analysis with monochromatic light (555 nm) was performed to determine the peak achievable simulated retinal image quality (IQ) and its degradation due to accommodative lags. The IQ was quantified in terms of the diffraction normalized metric, “light in the bucket, LIB”. Analysis was performed for a typical child either with or without Defocus Incorporated Multiple Segments (DIMS) spectacle lenses or NaturalVue (VTI; Alpharetta, GA) or Biofinity (CooperVision; Pleasanton, CA) center-distance (CD) multifocal contact lenses.
Results :
The peak values (perfect accommodation) of LIB for a typical aberrated child’s eye at viewing distances of 4m, 1m, 33cm and 20 cm were 0.36, 0.29, 0.27 and 0.19 respectively. Adding a NaturalVue multifocal contact lens changed these values to 0.15, 0.17, 0.3 and 0.22. Similarly, with Biofinity CD lens, the values were 0.18, 0.17, 0.22 and 0.18. Viewing through the central portion of a DIMS spectacle lens had minimal degradation effect, peak values of image quality metric being 0.32, 0.26, 0.25 and 0.20. However, viewing through the peripheral region containing the multiple defocus segments, image quality decreased to 0.08, 0.08, 0.09 and 0.09, respectively.
Conclusions :
For a perfectly accommodating eye, the pupil miosis induced with near viewing reduces the effect of higher order aberrations, however, counteracted by the increased negative spherical aberration of the eye. The presence of accommodative lags further degrades image quality at near. The central clear portion of DIMS spectacle lenses results in better image quality compared to the soft contact lens options evaluated. However, the peripheral portion substantially degraded image quality for all viewing distances. Image quality through NaturalVue and Biofinity CD lenses were comparable for all viewing distances.
This is a 2020 ARVO Annual Meeting abstract.