Abstract
Purpose :
Sensitivity to blur is decreased in the peripheral visual field of myopic eyes, which may be associated with retinal zones within the near-periphery that function as a retinal decoding system for optical blur. We used pattern electroretinograms (pERG) to evaluate whether this system is disrupted in the near-peripheral retina of myopes.
Methods :
ERGs were used to measure retinal responsivity in n=7 subjects with myopia (mean SE -2.59±1.38D, mean age 24±1 years) and n=5 subjects with emmetropia (mean SE -0.03±0.04D, mean age 26±2 years). Retinal activity was measured while subjects viewed naturalistic images with simulated optical blur. Images were convoluted to: (1) four different types of blur (Defocus, Spherical Aberration [SA], Astigmatism [J45], and a combination of Astigmatism and Defocus [J45+Defocus]; (2) blur from the periphery and up to one of three eccentricities (12, 6, or 0 degrees); and (3) three levels of blur (0.1, 0.3, or 0,5µm for Defocus, SA and J4, and 0.071, 0.213, or 0.354µm for J45+Defocus). Subjects viewed nine images for each type of blur and one no-blur condition in random order, for a total of 37 conditions. The N95 amplitude of the pERG was analyzed using a mixed model ANOVA to each parameter (within subjects factors: type of blur{Defocus, J45, SA, J45+Defocus}, blur amount{0.1, 0.3, 0.5}, eccentricity{12, 6, 0} and between subjects factor: refractive group{Myopes, Emmetropes}.
Results :
A main effect of amount of blur was found for each type of blur (Defocus: F=36.07, p<0.01; SA: F=12.58, p<0.01; J45: F=6.76, p<0.01; J45+Defocus: F=11.84, p<0.01) in both myopes and emmetropes. There were significant differences between responses to 0.1µm and 0.3µm blur for SA (p=0.01) and between 0.1µm and 0.5µm for all types of blur. A main effect of blur eccentricity was also found for Defocus (F=11.41, p<0.01), SA (F=14.25, p<0.01) and J45+Defocus (F=4.02, p=0.02). Significant interactions were found for eccentricity and the amount of blur for SA only. No main effect was found for refractive error group. The only difference between emmetropes and myopes in this study was found for 0.3µm of J45 blur (p=0.04).
Conclusions :
Differences in retinal responses with blur eccentricity suggest distinct retinal zones for blur decoding in both myopes and emmetropes. The effect of blur amount was larger than the effect of eccentricity or type of blur. No differences in retinal responses were found between emmetropes and myopes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.