Abstract
GOAL. Amblyopia–a loss of acuity in one eye following abnormal binocular experience during an early critical period–is a developmental disorder affecting ~3% of children. Recent research suggests that in addition to primary visual loss, amblyopes may also have deficient attention mechanisms. We investigated covert endogenous attention in juvenile and adult non-human primate amblyopes and visually normal controls. METHODS. We tested the effects of spatial cueing on subjects’ ability to discriminate the motion direction (rightward or leftward) of a target (a vertical grating patch) viewed monocularly at varying levels of contrast. The target appeared amidst an isoeccentric (3.5º) circular array of seven evenly spaced, differently oriented grating patches. All gratings drifted at the same speed but in different directions. Eye position was monitored by a remote eye tracker. We compared performance under valid cue (indicating the position of the upcoming target) and neutral cue (indicating all possible locations) conditions for each eye of each subject. RESULTS. We fitted psychometric functions to performance data and evaluated contrast gain (threshold shift) and response gain (change in maximum accuracy). The results showed that (1) attention improved accuracy and decreased reaction times for all eyes tested; (2) the effect of the valid cue was greater for amblyopic than for non-amblyopic or control eyes, so that performance for the two eyes of amblyopes was similar under valid cue conditions; (3) for amblyopic eyes, attention improved performance consistent with a change in both response gain and contrast gain, whereas for non-amblyopic and control eyes only contrast gain was observed. CONCLUSION. The results indicate that covert endogenous attention can improve amblyopic vision. We will discuss the distinct pattern of attentional effects for amblyopic eyes and control eyes according to a normalization model of attention.
Meeting abstract presented at VSS 2013