Do Multi-zone Contact Lenses Reduce Peripheral Hyperopic Defocus during Accommodation?

Abstract

Purpose : Hyperopically defocused retinal image is thought to provide signal for the eye to grow. Multi-zone contact lenses (CL) could potentially reduce hyperopic defocus or introduce myopic defocus. This study measured the refractive states across the pupil of subjects wearing multi-zone CL designs during on-axis and off-axis accommodation.

Methods : Five young myopic subjects aged 21 to 24 years were fit bilaterally with Comfilcon A single vision (SV), center-distance (CD) multifocal with +2D add, and center-near (CN) multifocal with +2D add CLs. While subjects accommodated binocularly to electronically displayed (iWatch) letter stimuli at 0D and -4D target vergences (TV), wavefront measurements (right eye) were acquired using a custom modified COAS-HD aberrometer along the visual axis, 30⁰ nasal and 30⁰ temporal fields. Raw wavefront slope data from each lenslet of COAS were used to develop a pupil map of axial refractive error.

Results : Mean ± SD spherical equivalent refraction was -4.77 ± 1.77D. As stimuli approached, the distribution of refractive states across the pupil after correcting for the TV, shifted towards hyperopia for all lenses indicating accommodative lag. With the multi-zone lenses, the distributions were wider and had more myopic defocus and less hyperopic defocus. In the fovea, the mean % increase in myopically defocused pupil area (relative to SV lens) with CD and CN lenses at 0D TV was 38% and 26%, and at -4D TV was 6% and 5%, respectively. Likewise, mean % decrease in the hyperopically defocused pupil area was 5% for both CD and CN at 0D TV, and 12% and 3%, respectively, for the -4D TV. In the nasal retina (30⁰), the mean % increase in myopically defocused pupil area with CD and CN lenses at 0D TV was 28% and 8%, and at -4D TV was 5% and 1%, respectively. Mean % decrease in the hyperopically defocused pupil area was 27% and 3% for CD and CN at 0D TV, and 17% and -4%, respectively, for the -4D TV. In the temporal retina (30⁰), the mean % increase in myopically defocused pupil area with CD and CN lenses at 0D TV was 38% and 4%, and at -4D TV was 4% and -3%, respectively. Likewise, mean % decrease in the hyperopically defocused pupil area was 27% and 10% for CD and CN at 0D TV, and 12% and -15%, respectively, for the -4D TV.

Conclusions : Comfilcon A CD lens effectively reduced the hyperopic defocus and increased the myopic defocus at the pupil plane during on-axis and off-axis accommodation.

This is a 2021 ARVO Annual Meeting abstract.