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Emily Jeong, Peter J Bex, Carles Otero, Fuensanta A Vera-Diaz; Perceptual responses to peripheral optical blur in myopia and emmetropia.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):546.
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© ARVO (1962-2015); The Authors (2016-present)
Blur signals play an important role in emmetropization. The purpose of our study is to measure sensitivity and sources of sensitivity differences to different types and levels of simulated optical blur across the visual field. We hypothesize that myopic individuals will show increased intrinsic blur and perceptual criteria, and this will increase with eccentricity.
Thirty (24.88±1.39yrs) healthy adults with myopia (n=16, SE: -3.20±2.85D) or emmetropia (n=14, SE: +0.07±0.20D) with best-corrected VA of 20/20 or better and no binocular or accommodative dysfunction participated. Blur discrimination thresholds were measured monocularly (dominant eye) with an adaptive 4AFC task. Participants observed dead leaves stimuli 50cm from a screen with a blur annulus at either 0°, 6°, or 12° eccentricity. Images were convolved with Spherical Aberration (SA), Defocus (Def), Astigmatism (Ast), or Defocus+Astigmatism (Def+Ast) kernels. Blur pedestal levels (0.01, 0.03, 0.09, 0.27, or 0.81 μm), and increments were applied to one quadrant of the image. Participants chose which of the four quadrants appeared blurriest. Blur discrimination thresholds were fit with a two-parameter (intrinsic blur and perceptual criteria) dipper function. Mixed model analyses and pairwise t-tests were used to compute the effects of blur and eccentricity.
Intrinsic blur showed an overall effect of eccentricity, with higher levels of blur at the more peripheral conditions and were overall significantly higher in myopes (P<0.010, η2=0.092). One-way ANOVAs showed higher intrinsic blur in myopes for SA (0deg: F=11.457, P=0.002; 6deg: F=7.203, P=0.012; 12deg: F=6.203, P=0.019), Def+Ast at 6deg (F=10.229, P=0.003) and Ast at 6deg and 12deg (6deg: F=9.343, P=0.005; 12deg: F=5.749, P=0.023). Perceptual criteria showed an overall effect of eccentricity with higher levels of blur at more peripheral conditions for Def (P<0.001, η2=0.243) and Def+Ast (P<0.001, η2=0.279), but not for SA or Ast. No main significant interaction between eccentricity and refractive group was found for blur threshold in any type of blur.
Intrinsic blur was higher in myopes and more pronounced in the periphery for SA, Ast, and Def+Ast, indicating that myopes have more difficulty discriminating these types of blur. This effect was not found for Def. Perceptual criteria are also eccentricity-dependent, but no differences between refractive groups was found.
This is a 2020 ARVO Annual Meeting abstract.
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