Abstract
The purpose of the experiments was to investigate the spatial and especially the temporal distortions in amblyopic vision, and to relate them to the orthoptic status and the contrast sensitivity of the amblyopic subjects, as well as to their performance in psychophysical tasks. In the first experiment participants were asked to describe their perception of the amblyopic eye for patterns of different spatial frequencies (0.4 − 3.2 c/deg). In the second and third experiments, subjects had to reconstruct concentric circles point by point. The radial position of each point was to be recontructed after visual presentation, while the angular position was presented either auditively (second experiment) or visually (third experiment). Twelve out of 14 amblyopes perceived spatial distortions. Five out of 10 strabismic and strabismic-anisometropic, but only 1 out of 4 anisometropic amblyopes perceived temporal instability. Temporal distortions were seen only for spatial frequencies higher than 1.6 c/deg. Temporal instability involved either the whole pattern or only some parts of it. There was no relationship of contrast sensitivity loss to the type or severity of distortion. In experiments 2 and 3, considerable distortions were perceived in the amblyopic eye for strabismic and strabismic-anisometropic amblyopes. In addition, subjects who perceived temporal instability showed a significantly impaired performance in adjusting the auditively presented points. The experiments suggest that strabismus, in addition to amblyopia, is needed to elicit significant spatial and temporal distortions. Temporal instability appears in addition to spatial distortions and has a negative impact on the performance in psychophysical tasks. Strabismic amblyopes show deficits in auditory-to-visual mapping, suggesting an impairment of the dorsal pathway, in addition to the known deficits of the ventral visual pathway.
Acknowledgements: Supported by a grant from Deutsche Forschungsgemeinschaft (Si 344/17-1,2)