Local and non-local deficits in amblyopia: acuity and spatial interactions

Amblyopic vision is thought to be limited by abnormal long-range spatial interactions, but their exact mode of action and relationship to the main amblyopic deficit in visual acuity is largely unknown. We studied this relationship in a group ( N = 59) of anisometropic ( N = 21) and strabismic (or co...

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Bibliographic Details
Published in:Vision research (Oxford) 2004-12, Vol.44 (27), p.3099-3110
Main Authors: Bonneh, Yoram S., Sagi, Dov, Polat, Uri
Format: Article
Language:English
Subjects:
Adolescent
Adult
Amblyopia
Amblyopia - physiopathology
Amblyopia - psychology
Anisometropia
Anisometropia - physiopathology
Anisometropia - psychology
Biological and medical sciences
Contrast Sensitivity
Crowding
Discrimination (Psychology)
Humans
Male
Medical sciences
Middle Aged
Oculomotor disorders
Ophthalmology
Pattern Recognition, Visual
Perceptual Masking
Sensory Thresholds
Space Perception
Spatial-interactions
Strabismis
Strabismus - physiopathology
Strabismus - psychology
Visual Acuity
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Summary:Amblyopic vision is thought to be limited by abnormal long-range spatial interactions, but their exact mode of action and relationship to the main amblyopic deficit in visual acuity is largely unknown. We studied this relationship in a group ( N = 59) of anisometropic ( N = 21) and strabismic (or combined, N = 38) subjects, using (1) a single and multi-pattern (crowded) computerized static Tumbling-E test with scaled spacing of two pattern widths (TeVA), in addition to an optotype (ETDRS chart) acuity test (VA) and (2) contrast detection of Gabor patches with lateral flankers (lateral masking) along the horizontal and vertical axes as well as in collinear and parallel configurations. By correlating the different measures of visual acuity and contrast suppression, we found that (1) the VA of the strabismic subjects could be decomposed into two uncorrelated components measured in TeVA: acuity for isolated patterns and acuity reduction due to flanking patterns. The latter comprised over 60% of the VA magnitude, on the average and accounted for over 50% of its variance. In contrast, a slight reduction in acuity was found in the anisometropic subjects, and the acuity for a single pattern could account for 70% of the VA variance. (2) The lateral suppression (contrast threshold elevation) in a parallel configuration along the horizontal axis was correlated with the VA ( R 2 = 0.7), as well as with the crowding effect (TeVA elevation, R 2 = 0.5) for the strabismic group. Some correlation with the VA was also found for the collinear configuration in the anisometropic group, but less suppression and no correlation were found for all the vertical configurations in all the groups. The results indicate the existence of a specific non-local component of the strabismic deficit, in addition to the local acuity deficit in all amblyopia types. This deficit might reflect long-range lateral inhibition, or alternatively, an inaccurate and scattered top–down attentional selection mechanism.
ISSN:0042-6989
1878-5646
DOI:10.1016/j.visres.2004.07.031