Contrast sensitivity in amblyopia. II. Changes during pleoptic treatment.

Contrast sensitivity at spatial frequencies 1-19 c/deg was measured in 56 children (mean age 10 years), who had received pleoptic treatment. Measurements were done at the beginning and at the end of a pleoptic treatment period as well as at follow-up using vertical gratings. A deficiency was observed in contrast sensitivity of amblyopic eyes at all spatial frequencies, but it was most notable at high spatial frequencies. Both types of CSF presented by Hess & Howell (1977) were found in all groups of amblyopia. A statistically significant improvement in the mean value of contrast sensitivity of the amblyopic eyes was observed at all spatial frequencies during the pleoptic treatment, although in 12 cases fixation and vision did not improve. Correlation with the improvement in visual acuity was poor. In several cases a change was observed in only one of the two parameters in question. Regarding the better eye, there were some signs of 'hidden occlusion amblyopia': in a few cases contrast sensitivity of the dominant eye deteriorated during the treatment period without a changes in visual acuity only to risk back to the previous level at the follow-up.