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Atanu Ghosh, Len Zheleznyak, Antoine Barbot, Geunyoung Yoon; Effect of blur adaptation on peripheral visual performance in myopes and emmetropes. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4396. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effect of blur adaptation (2D myopic defocus) at fovea (0°) and parafovea (10°) over time in emmetropes and myopes with and without higher order aberrations (HOAs).<br />
An adaptive optics (AO) vision simulator was used to measure high contrast tumbling E visual acuity (HCVA) at fovea and at 10° nasal visual field before, during and after a 60 min blur adaptation. 6 young adults (3 emmetropes and 3 myopes) participated in this study, and were dilated with phenylepherine eye drops. Visual performance was measured over 6-mm pupil under two conditions: (i) HCVA measured with corrected HOAs before and after a 60 min adaptation in which aberrations were dynamically corrected with closed-loop AO, and (ii) HCVA measured with subject’s native HOAs every 10 min over a 60 min adaptation period; i.e., the time course of blur adaptation observed. During blur adaptation subjects watched video at 2m distance using their foveal (0°) and parafoveal (10°) vision, while wearing a +2D trial lens and 6-mm artificial pupil, in two separate, counter balanced sessions.<br />
Defocused HCVA with corrected HOAs improved significantly after 60 min of blur adaptation for both foveal (group mean logMAR: 0.65±0.06 and 0.58±0.07 before and after adaptation, respectively, p=0.03) and parafoveal vision (group mean logMAR 0.85±0.03 and 0.78±0.06 before and after adaptation, respectively, p=0.01). When the subjects’ native HOAs remained uncorrected we also observed significant improvements in HCVA over time for both foveal (R2= 0.859; mean HCVA improved by 36%) and parafoveal (R2= 0.788; mean HCVA improved by 11%) vision (ANOVA, time, p<0.01). Myopic subjects had significantly greater improvement in parafoveal HCVA after 60 min of adaptation with the corrected HOAs condition (mean HCVA improvement: logMAR 0.10±0.02), than that of emmetropic subjects (mean HCVA improvement: logMAR 0.04±0.03). However there was no significant difference observed in parafoveal HCVA after 60 min of adaptation between refractive error groups (mean difference: logMAR 0.02±0.02), when subject’s HOAs remained uncorrected.<br />
Myopes exhibited a greater level of adaptation to peripheral defocus than emmetropes, while optics of the eye in both groups was fully corrected. This finding suggests that neural compensatory response to myopic defocus might have different impact on peripheral visual performance in myopes and emmetropes.<br />
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