Abstract
Purpose: :
To investigate the effect of pupil size and ocular wavefront aberration on visual performance under binocular and monocular conditions.
Methods: :
Ten eyes from 10 subjects (mean age 21.3) were included in the study. Pupil diameter was continuously recorded during contrast visual acuity (logMAR scale) measurement with modified CAT–2000 (Menicon, Japan). Aberrometry measurements were performed with ARK–10000 (Nidek, Japan). Zernike coefficients were recalculated for natural pupil diameters under binocular and monocular conditions, using Schwiegerling’s algorithm to recalculate the expansion coefficient. In monocular condition, non–measurement eye during contrast visual acuity measurements were covered with two shields – a back patch and a density filter – to investigate whether the change in pupil diameter from binocular to monocular condition depends on retinal illuminance of non–measurement (covered) eye.
Results: :
In every contrast of visual target, mean pupil diameter and total higher–order aberration increased significantly under monocular condition covered with a black patch, as compared to monocular condition covered with a density filter and binocular condition (p<0.01, ANOVA, Fisher's PLSD test). Monocular visual acuity with a black patch under low contrast of visual targets was significantly worse than that with a density filter and binocular acuity (p<0.05, ANOVA, Fisher's PLSD test).
Conclusions: :
These results suggest that increase in pupil diameter from binocular to monocular condition give rise to increase in higher–order aberration with every contrast of visual target, impacting low contrast visual acuity and binocular summation, and the change of pupil diameter depends on retinal illuminance of non–measurement eye.
Keywords: pupil • visual acuity • optical properties