Visual Performance as a Function of Clear Central Aperture Diameter with a Defocused Myopic Periphery

Abstract

SIGNIFICANCE:Visual performance is affected least by a 15°radial aperture surrounded by peripheral myopic defocus. This finding has important applications for spectacle and contact lens designs and myopia control optimization. PURPOSE:The purpose of this study was to assess the effect of clear central apertures of different diameters with a defocused retinal periphery, using a range of visual performance tasks.METHODS: Thirty visually normal subjects (mean age, 24.4 ± 3.3 years; 20 females; mean spherical equivalent of −1.28 D) were enrolled. Subjects wore five different spectacles during testing, all corrected for distance refraction, in random order: three single-vision spectacles with clear central apertures of 10, 12.5, and 15°radii with the periphery defocused using Fresnel "press-on" lenses (+3.5 D sphere), progressive addition lens (PAL) spectacles with a +3.5 D addition, and single-vision lens (SVL) spectacles with no peripheral defocus. Static and kinetic visual field sensitivities, reading rate and comprehension, head movements, global saccadic tracking, and saccadic visual search were evaluated. RESULTS:Reading rate and comprehension did not differ across the five test conditions; however, increased head movement was found with the smallest aperture compared with the PAL condition with adjusted P < .05. Static visual field sensitivity was reduced for all three apertures in eccentric regions when compared with the SVL and PAL conditions with adjusted P < .05, whereas kinetic sensitivity did not differ for any lens condition. The 15°aperture was superior to the 10 and 12.5°apertures based on its similarity to the SVL and PAL spectacle conditions in head movement during reading, the Michigan Tracking Test, and the vertical results of the Developmental Eye Movement Test.CONCLUSIONS: Visual performance is least affected adversely by a 15°aperture surrounded by a peripheral myopic defocus. This finding has important applications for spectacle and contact lens designs to optimize myopia treatment with minimal impact on visual performance.

Effect of short-term peripheral myopic defocus on ocular biometrics using Fresnel “press-on” lenses in humans

“…We examined biometric changes in adult human subjects with a non-invasive methodology using two different magnitudes of dioptric (D) defocus supplied by peripherally placed Fresnel lenses, leaving the central 11.5 mm of visual field unaffected (i.e., leaving a clear central visual field of approximately 23°). This diameter was found to be optimal for central visual performance, compared to the other lesser diameters 20 .…”

“…The rationale for the size of the clear, central aperture came from our previous set of experiments where we showed that the 11.5 mm aperture was optimal in terms of visual performance compared to smaller apertures 20 . Two different dioptric powers of the Fresnel lenses were used in the study, + 3.50 and + 5.00 D. Twenty subjects completed the defocus session for the + 3.50 D condition.…”