Changes in the visually evoked response during treatment for amblyopia in a uniocular patient.

Changes occurred in the visually evoked response (VER) during treatment for amblyopia in a uniocular patient. The VER changed before the visual acuity. After-image treatment was used to teach central fixation and this was maintained with the use of television chequerboards. The patient's visual acuity improved from 4/60 to 6/12 and this was confirmed by the evoked responses.

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.

Effect of occlusion on the visual evoked response in amblyopia.

Average normal values for the VER were obtained in children aged 4 to 11 years. There are slight but significant differences between the values obtained and those found in adults (an increase in the time to peak of P1). In amblyopic eyes the time to peak is increased, and the amplitude reduced, roughly in proportion to the loss of visual acuity and binocularity. The VER is normal in the better eyes of children who have never been treated by occlusion therapy. Occlusion increases the time to peak of the VER, both in serial studies on individuals, and in lateral population studies, so that the response of the better eye is delayed beyond that of the amblyopic eye. After the end of occlusion, the VER change usually returns to normal. In a subgroup of patients with prolonged occlusion, the changes had not completely reversed one year later. In children in whom occlusion therapy had improved visual acuity, the VER returned towards normal.

Bull's eye maculopathy with early cone degeneration.

Seven patients with acquired cone degeneration were investigated. The initial visual acuities in 6 of the series were normal or near normal but later deteriorated, although they did not fall below 6/60 in any patient. All the patients tested had colour vision defects and abnormalities on electrodiagnostic testing referable to the cone system. The typical picture was of a bull's eye maculopathy accompanied by an annular scotoma around the fovea, but the clinical and electrophysiological investigations showed that there were considerable variations especially in the early stages.