Changes in the visual evoked response during and after occlusion therapy for amblyopia.

The VER was studied in normal children aged 4--11 years and in 71 amblyopic children at Moorfields Eye Hospital. Changes in the VER in amblyopia are best observed with 20% contrast and small square sizes. The better eye of untreated amblyopia has a normal time-to-peak for P1 of the cortical response, while that of the amblyopic eye is delayed, the more so with poor binocular vision in partial agreement with our previous findings. We found with a high degree of significance that occlusion therapy renders the VER from the amblyopic eye more 'normal' but causes considerable delay in the VER from the covered eye, even though its visual acuity does not change. At the end of occlusion, these changes are usually reversible although not always completely in patients who have had prolonged occlusion.