Abstract
Amblyopia is characterized by a reduced visual acuity and lower contrast sensitivity in the amblyopic eye, particularly at high spatial frequencies. Despite this generalization, there are also large inter-individual differences of contrast sensitivity between amblyopic observers. In this study, we analyzed these differences to investigate the spatial frequency channels in amblyopia. To determine the spatial frequency channels in amblyopia, we ran a meta factor-analysis on 5 datasets taken from our previous studies using a principal component analysis followed by a varimax rotation of the components. In the range of 0.25 to 10 c/d, this analysis revealed two spatial frequency channels: one low- and one high-, peaking around 0.5 and 2 c/d respectively. Interestingly, those presented very similar tuning in the amblyopic eye and the fellow eye. The only major difference was in the weight attributed to the high frequency channel. It was reduced by approximately 50% in the amblyopic eye. Nevertheless, the sensitivities in these 2 channels were correlated for both the amblyopic eye and fellow eye. These findings suggest that there is no fundamental mechanistic deficit in contrast sensitivity of amblyopia and that high spatial frequencies might just be attenuated in the amblyopic eye. Our findings support the usage of binocular therapies that rely on the premise of rebalancing the relative contrasts between both eyes and the assumption that both eyes can be binocularly fused.