| dc.description | Amblyopia is a neuro-developmental disorder of the visual system that is defined as a loss of visual acuity that cannot be corrected with lenses nor attributed to a disease. Although amblyopia is defined as a loss of visual acuity, the condition is further characterized by other visual anomalies, including large deficits of spatial localization. Because the latter aspect of amblyopic vision has not been addressed by animal models of amblyopia, the spatial localization abilities of visually deprived kittens were investigated using the same spatially bandpass stimuli as those employed for the assessment of human amblyopes. The tests were conducted on 2 normal kittens, 2 animals reared with a strabismus and 6 other kittens following different periods of early monocular deprivation. Measurements were made of the accuracy with which the animals could detect a misalignment between three Gaussian blobs of high contrast. Alignment accuracy for both normal and the non-deprived eye of the visually deprived kittens increased in a proportional manner to the spatial scale of the stimuli, a result comparable to that observed in normal humans. As with human amblyopes, the deficits in alignment accuracy were scaled in proportion to blob size but were in general larger than those reported in human amblyopes. Moreover, the alignment deficits were considerably larger than those of grating acuity. Tests with stimuli of various contrasts revealed that the deficits in the deprived eyes could not be explained in terms of the contrast sensitivity loss in this eye. Comparisons of the ratios of alignment accuracy between the amblyopic and the non-amblyopic eyes of the visually deprived animals with the corresponding ratios for contrast discrimination revealed that the former were much larger than the latter, a result that conflicts with simple versions of models of the spatial localization deficits based on neural undersampling. The close similarities between the spatial localization deficits found in amblyopic cats and those found in human amblyopes provide strong support for the use of this particular animal model for study of the neural basis of human amblyopia. | en_US |
