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Fuensanta A Vera-Diaz, Anna Kosovicheva, Adriana Ferreira, Peter J Bex; Effect of Temporal Vision on Binocularity in Ametropia. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2742. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
A person’s ability to process and use temporal visual information may affect the binocular balance between the two eyes and their perception of depth (stereopsis). We hypothesize that differences in retinal profile may influence the effect of temporal vision on binocularity in individuals with ametropia.
Forced choice tasks were used to quantify binocularity as a function of flicker (0, 4, 7.5, and 12Hz) and spatial frequency (1, 2, 4, and 8cpd). Interocular Contrast Ratios (ICR) were measured by determining the relative contrast at which subjects reported seeing two dichoptic Sloan letters with equal frequency (Kwon et al, 2014). Stereopsis thresholds were evaluated by determining the minimum disparity at which subjects identified a front-depth target with 75% accuracy. Subjects were 34 young adults (22-31yrs) with best-corrected VA 0.0 LogMAR (20/20) or better in each eye and no binocular or accommodative dysfunction measured by clinical tests. Refractive correction was determined by binocular subjective refraction. Subjects were classified into: Myopes (-0.80 to -9.00D, n=15), Emmetropes (+0.40 to -0.25D, n=13), or Hyperopes (+4.00 to +0.70D, n=6).
Deviations from binocularity, quantified as the strength of the difference between the two eyes (difference of the ICR from 50%), were found to be spatial frequency dependent (F=4.24, p<0.01), but not temporal frequency dependent (F=2.07, p=0.11). In contrast, stereoacuity thresholds were both spatial (F=3.00, p=0.04) and temporal frequency (F=3.68, p=0.02) dependent. In addition, we observed temporal and spatial frequency-dependent differences in binocularity between the refractive error groups. A significant three-way interaction indicated that myopes show higher suppression at higher spatial frequencies and lower temporal frequencies than emmetropes (F=2.28, p=0.02). Myopes also showed larger stereoacuity thresholds at 4Hz (t=2.49, p=0.02).
Subjects with myopia but otherwise clinically normal vision show a trend towards a temporal frequency-specific reduction in binocularity, as shown by increased stereopsis thresholds and increased suppression. This potential effect of temporal frequency in the ability to perceive depth in myopes may be consistent with previously reported deficits in their magnocellular pathway. However, the specifics of abnormal temporal vision processing in emmetropization are yet to be determined.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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