Visual spatial filtering and pattern discrimination are abnormal in strabismic amblyopia

Bromley, J. M.; Javadnia, A. and Ruddock, K. H. (1987). Visual spatial filtering and pattern discrimination are abnormal in strabismic amblyopia. Clinical Vision Sciences, 1(3) pp. 209–218.

Abstract

1. We report the results of an experimental study on normal and amblyopic vision, in which we have measured spatial filter characteristics and pattern discrimination performance.

2. Threshold responses, measured for each eye of amblyopes, in response to a moving target of either positive (light) or negative (dark) contrast, are displaced to lower spatial frequencies than those for normal vision. These data, which are similar to those reported previously for light targets, imply a loss of spatial resolution.

3. Discrimination of target orientation, measured for multi-element stimuli of linear dimension 0.5 deg, is significantly impaired for the abnormal eyes of the amblyopic subjects compared with their performance under binocular conditions, whereas responses for the "normal" eyes are similar to the binocular data.

4. For larger targets (linear dimensions 1.5 deg), data for both "abnormal" and "normal" eyes are similar to those for binocular viewing, and the deficit observed with small targets can be simulated in normal subjects by degrading or demagnifying the retinal image.

5. We show that in amblyopia, discrimination losses for the "abnormal" eyes cannot be attributed solely to changes in the spatial filter responses. We argue that the discrimination losses observed in our experiments are consistent with blurring of images in amblyopia.

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