Temporal instability of visual perception in strabismic amblyopia

Abstract

Purpose: To evaluate the spatial and temporal distortions in strabismic and anisometropic amblyopic vision. Main focus was on the temporal instability which was reported quite often but never investigated in detail. Methods: Amblyopic participants were asked to describe and draw their subjective percept of patterns of different spatial frequencies seen with the amblyopic eye. A matching task was performed to test the reliability of the amblyopic perception. We used a pair comparison task in which the amblyopic subjects saw the distorted patterns with the dominant eye and had to decide which of them matches best their amblyopic perception. Results: Three out of four strabismic and two out of three strabismic-anisometropic, but only one out of four anisometropic amblyopes sensed temporal instability. This was only true for higher spatial frequencies, spatial distortions in the low spatial frequency domain had a stable character. The type of temporal instability was twofold: either the whole pattern was perceived as jittering or some parts of the pattern were perceived as moving. The result of the matching task showed much less pronounced distortions than expected from the drawings. But the structure and complexity of the spatial and temporal distortions remained the same. Conclusions: It seems that amblyopes experience and describe their distortions subjectively more vividly than can be captured accurately in quantitative experiments (see also Hess et al., 2003). This is also consistent with previous results from our group: quantitative data differ from qualitative descriptions and only partially reflect the amblyopic perception (Sireteanu et al, 1993).

Footnotes

 Supported from a grant from the Deutsche Forschungsgemeinschaft (Si/17-1)