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L. Sawides, P. de Gracia, C. Dorronsoro, E. Gambra, M. Webster, S. Marcos; Adapting to Blur Produced by Ocular High Order Aberrations. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6347.
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© ARVO (1962-2015); The Authors (2016-present)
(1) To evaluate the effect of adaptation to High Order Aberrations (HOA). (2) To examine if the adaptation is selective for each subject’s own aberrations.
Blur judgements were measured in 4 subjects to images degraded by different amounts of HOA, before (gray screen) and after prior adaptation to images with 5 levels of optical degradation (from sharpest to double the amount of natural blur). A custom-developed Adaptive-Optics (AO) system (provided with an electromagnetic deformable mirror and Hartmann-Shack wavefront sensor) was used to measure and correct the subject’s HOA. A psychophysical channel allowed the presentation of gray-scale images on a CRT monitor viewed through a Badal system (which corrected for spherical error) and the deformable mirror. Each subject viewed 1.98-deg face stimuli degraded by his/her own HOA, as well as by the other subjects’ HOA. Optical blur was generated by convolution of the corresponding PSF with the image, and ranged from diffraction-limit (0×) to 2× the natural HOA of each eye, at 0.05× steps. Adapting images were jittered in time to prevent local light adaptation and presented for 60s at the beginning and 5s between trials. AO-correction and pupil centration were continuously monitored and controlled during the experiment. A 2AFCP (Blur/Sharp) with a QUEST algorithm was used to estimate the subject’s perceived focus point in each condition. The results were analysed in terms of the shift of the perceived focus point before (gray) and after adaptation to sharp, natural and blurred images.
Natural HOA RMS ranged from 0.18 to 0.39 um (5-mm pupils), and AO correction produced practically diffraction-limited performance. (1) All subjects adapted to the blur imposed by HOA. Adaptation to a sharp image (0×) shifted the perceived focus point toward sharper levels by -0.14±0.04 µm RMS on average, while adapting to a blurred image (1.5× RMS) to more blurred levels by 0.07±0.03 µm on average. The effect is proportional to the amount of blur, with saturation at over ×1.5 RMS blur (except for one subject who showed saturation at 1×). (2) Aftereffect magnitude differed when the subject adapted to their own vs. other subject's HOA. The perceived focus point without prior adaptation differs by less than 0.03 µm on average from that after adaptation to his/her natural aberrations.
(1) Subjects can adapt to blur produced by ocular HOA, and the effect depends on the amount of blur. (2) Different aftereffects occur when adapting to proper vs. someone else's HOA, suggesting that subjects are adapted to their own natural aberrations.
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