Blur Perception in Near-Peripheral Retina

Title Blur Perception in Near-Peripheral Retina
Author, Co-Author Lenna Walker, Guido Maiello, Peter Bex, Nancy Coletta, Fuensanta Vera-Diaz
Topic Functional Vision/Pediatrics
Program Number
Ballroom A-B
New England College of Optometry

Purpose: An ability to accurately detect and respond to blur and an adequate balance between central and peripheral retinal stimulation may be required for emmetropization. We evaluated sensitivity to blur across the visual field.

Methods: Subjects were 37 young (23-30yrs) healthy adults (n = 18 myopes) with best-corrected VA 0.0 LogMAR (20/20) or better in each eye and no binocular or accommodative dysfunction. Refractive error was determined by binocular subjective refraction.

Monocular and binocular blur discrimination thresholds were measured as a function of pedestal blur using an adaptive 4AFC task. Stimuli were presented in a 50° diameter window @ 40cm. Gaussian blur pedestals were confined to an annulus at 0°, 4°, 8° and 12° eccentricity, with a blur increment applied to one quadrant of the image. Blur discrimination thresholds were fit with a two-parameter (intrinsic blur and blur sensitivity) dipper function.

Results: The level of intrinsic blur increased for retinal eccentricities beyond 4° (p < 0.001) and was lower in binocular than monocular conditions (p < 0.001). There was no correlation between refractive error and intrinsic blur.

Blur sensitivity decreased with retinal eccentricity (p < 0.001). Overall, blur sensitivity was higher for binocular viewing (p = 0.02). There was a trend towards lower blur sensitivity in myopes for all conditions, although a significant difference was not found (p = 0.08). A positive correlation was found between refractive error and monocular blur sensitivity at 4° (ρ = 0.3991, p = 0.02), but no other correlations were found between refractive error and blur sensitivity.

Conclusions: Intrinsic blur increases and blur sensitivity decreases with retinal eccentricity. Although not statistically significant, a trend was found that suggests myopes may experience a greater difficulty discriminating blur. Binocular viewing seems to ameliorate some of this difficulty, but the trend still persists.

Affiliation of Co-Authors University College London (UCL); Northeastern University, Northeastern University, New England College of Optometry, New England College of Optometry