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Ramkumar Sabesan, Len Zheleznyak, Bjorn N. Vlaskamp, Sowmya Ravikumar, Martin S. Banks, Geunyoung Yoon; Impact of Ocular Higher Order Aberrations on Stereopsis. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3661.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate if the precision of stereopsis is improved after binocular higher order aberration correction in normal eyes
A binocular adaptive optics (AO) vision simulator consisting of 2 individual monocular channels was employed to measure stereopsis. Each monocular AO system consisted of a Shack-Hartmann wavefront sensor, a large-stroke deformable mirror and a visual stimulus display. A movable nonius target was displayed before each stimulus presentation to ensure fusion. Four cyclopleged normal subjects were recruited for the study. Binocular 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) in 3 subjects to demonstrate the vision improvement after higher order aberration correction. The finest perceivable corrugation in depth, was measured using random dot stereograms with increasing dot density (75, 110, 160 dots/deg2) under the same conditions in all subjects for 5.8mm pupil to investigate the optical limit to stereopsis. Vision testing was performed in white light for all conditions. Visual benefit was quantified as the ratio of visual performance with AO to without AO.
The average higher order RMS in the four subjects was 0.35±0.12µm and 0.37±0.10µm in the right and left eye respectively over a 5.8mm pupil. Binocular higher order aberration correction led to an average improvement in visual acuity by a factor of 1.25 and contrast sensitivity by a factor of 1.3, 1.6, 1.9 and 2.3 for 4, 8, 16 and 24 c /deg respectively. Stereopsis with AO also improved by a factor of 1.1, 1.2 and 1.3 on average for 75, 110, 160 dots/deg2 compared to without AO. The improvement was statistically significant (p<0.03) at 110 and 160 dots/deg2. The maximal improvement in stereo-resolution was observed in the subject with the most aberrated optical quality. The finest perceivable corrugation with AO was slightly smaller than the Nyquist limit by 0.70, 0.72, 0.15 c/deg at 75, 110, 160 dots/deg2 respectively.
The precise stereo processing of the visual system in the well-focused eye is limited by higher order aberrations and undergoes a significant benefit upon correction.
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