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Ramkumar Sabesan, Len Zheleznyak, Kamran Ahmad, Geunyoung Yoon; Impact of Correcting Higher Order Aberrations on Binocular Visual Performance and Summation. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4768.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the visual benefit after binocular higher order aberration correction and how the improved retinal image quality affects binocular summation
A binocular adaptive optics (AO) system for vision testing was constructed with two identical monocular AO channels. Each monocular AO system consisted of a Shack-Hartmann wavefront sensor, a large-stroke deformable mirror (Mirao-52) and a visual stimulus display. Two identical apertures placed in the retinal conjugate planes of both AO channels served as a binocular fusion lock. Five cyclopleged normal subjects were employed for the study. Tumbling ‘E’ high contrast visual acuity and contrast sensitivity (4, 8, 16, 24 c/deg) were measured for a 6 mm pupil under correction of defocus and astigmatism alone (without AO) and correction of all aberrations (with AO). Both monocular and binocular visual performance was measured. Visual benefit was quantified as the ratio of visual performance with AO to without AO. Binocular summation factor was defined as the ratio of binocular to averaged monocular visual performance.
Binocular higher order aberration correction led to an average improvement in visual acuity by a factor of 1.2 and contrast sensitivity by a factor of 1.2, 1.5, 1.8 and 2.0 for 4, 8, 16 and 24 c /deg respectively. This binocular visual benefit was smaller than monocular visual benefit by 7.2% for visual acuity and 14.5%, 11.7%, 22.1% and 36.6% for 4, 8, 16 and 24 c /deg respectively (p<0.05). Without AO, binocular summation factor was 1.16 in visual acuity and 1.5 in contrast sensitivity on average across all spatial frequencies. With AO, binocular summation factor was reduced to 1.08 in visual acuity and 1.3 in contrast sensitivity (p<0.05). The reduction in the summation factor was highly correlated with the reduction in binocular visual benefit (R2 = 0.93).
In both visual acuity and contrast sensitivity, binocular higher order aberration correction provides reduced visual benefit compared to the monocular case. This may be caused by the decreased binocular summation observed upon aberration compensation.
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