Contrast sensitivity deficits in amblyopia

M Kwon1, L Lesmes2, A Miller3, M Kazlas4, M Dorr2, D G Hunter5, Z-L Lu6, P Bex1

1Department of Ophthalmology, Harvard Medical School, MA, United States
2Schepens Eye Research Institute, Harvard Medical School, MA, United States
3Harvard Medical School, MA, United States
4Ophthalmology, Boston Children's Hospital, United States
5Harvard Medical School, Boston Children's Hospital, MA, United States
6Cognitive and Behavioral Brain Imaging, Ohio State University, OH, United States
Contact: miyoungkwon02@gmail.com

Loss of contrast sensitivity is one of the core deficits in amblyopia. Here we examined the patterns of contrast sensitivity deficits in anisometropic amblyopia, strabismic amblyopia, and strabismus without amblyopia. For subjects with these visual impairments, and a normal cohort, we measured three contrast sensitivity functions (CSFs): two monocular and one binocular. Measurement of three CSFs over a relatively short testing time (10-15 min) was enabled by the quick CSF method (Lesmes et al, 2010). Our results showed that the high frequency cutoff of the CSF was highly correlated with conventional logMAR acuity, for all conditions. Consistent with previous findings, contrast sensitivity was significantly reduced in the amblyopic eye. Neither amblyopic group showed evidence of binocular summation: binocular and better-eye CSFs were the same. Strabismics without amblyopia also showed no binocular summation, and did not show differences in sensitivity between eyes. Furthermore, a principal components analysis classifier showed that the CSF of the worse eye and the difference between eyes explain most of the variance in these diverse subjects. We conclude that monocular and binocular CSF deficits are defining characteristics of amblyopia. Our results further demonstrate that the quick CSF provides an efficient assessment tool for vision research.

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