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Goro Maehara, Benjamin Thompson, Behzad Mansouri, Reza Farivar, Robert Hess; Luminance contrast thresholds in patients with amblyopia under monocular and dichoptic viewing. Journal of Vision 2015;15(12):264. doi: 10.1167/15.12.264.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: We investigated whether simply opening the fellow eye triggers suppression of the amblyopic eye or whether stimulation of the fellow fixing eye is required for suppression. Methods: We measured luminance contrast thresholds either for the amblyopic eye or fellow fixing eye using a haploscope. A square frame was presented to each eye to aid binocular fusion. In experiment 1, two gratings appeared within diagonal quadrants (e.g. top-left and bottom-right) of one eye. The other eye was either occluded with an eye patch or viewed a black background. In experiment 2, two gratings appeared within the diagonal quadrants of one eye and another two gratings were shown to the opposite quadrants of the other eye. One pair of gratings were the targets to detect and the other pair were dichoptic maskers. Results and Discussion: A two-way ANOVA with factors of eye and patching was conducted on the thresholds from experiment 1. Although thresholds were significantly higher for the amblyopic eye than for the fellow fixing eye, the difference was relatively small. This could be due to the low spatial frequency of the gratings. The effect of patching and the interaction were not significant. That is, thresholds for the amblyopic eye were only minimally elevated when the eye patch was removed from the fellow fixing eye. On the other hand, the patients exhibited much higher thresholds when the dichoptic masker gratings were presented in experiment 2. These results suggest that just opening both eyes is not sufficient to elicit strong suppression of the amblyopic eye and that dichoptic stimulation is required to trigger suppression. Furthermore, the suppression was not confined to the quadrants that contained the masks but extended to the quadrants containing the targets. This suggests the presence of long-range suppressive interactions within the amblyopic visual cortex.
Meeting abstract presented at VSS 2015
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