Abstract
Purpose: :
In anisometropic amblyopic children, protracted dichoptic stimulation may result in interocular suppression, which may be a contributing factor in the development of amblyopia. The present study was undertaken to investigate the role of interocular interactions in anisometropic amblyopia development.
Methods: :
Groups of normally sighted children, anisometropic children and anisometropic amblyopic children were recruited from school screening in China. Each group consisted of 35 children from 5 to 10 years, with approximately equal numbers of males and females. Low contrast visual acuity, contrast sensitivity and alignment sensitivity were measured in each subject in both dichoptic and monocular viewing conditions. Visual stimuli were generated using a specialised graphics card and were displayed on a flat profile monitor. Trial frames were used in all experiments with trial lenses to achieve best corrected visual acuity. An opaque occluder and a pinhole were used in monocular conditions. In dichoptic conditions, a star-shaped partial occluder was in front of the non-tested eye (allowing no central vision) and a pinhole was in front of the tested eye. Interocular interaction was measured on the basis of the extent to which the tested eye was affected by dichoptic versus monocular stimulus presentation, thus an interocular interaction index was calculated as difference between dichoptic and monocular thresholds.
Results: :
Interocular interaction index was not significantly different in any subject groups when the occluder was in front of the non-dominant eye. When the occluder was in front of the dominant eye, interocular interaction index was significantly higher in amblyopic children than in anisometropic children without amblyopia in all three visual function tests.
Conclusions: :
The interocular interactions tested here differed between anisometropic children with and without amblyopia, indicating interactions of this kind may play a role in the development of anisometropic amblyopia.
Keywords: amblyopia • visual development • perception