[Temporal integration in diseased eyes. III. Fixation movements in visual acuity testing]

The fixation movements which occur during visual acuity testing were observed in order to clarify the mechanism behind the critical duration in visual acuity testing, which we found in a previous study to be significantly longer in central serous retinopathy and macular edema. Photoelectric oculography (p-EOG) was used to record horizontal eye movement in this study. In normal eyes the frequency and amplitude of the microsaccades were smaller while the acuity target was shown than when it was not shown. This phenomenon was also observed in eyes with macular edema. These results suggest that microsaccades play no positive role in the reading of visual acuity targets, and that they bear little relation to the phenomenon of critical duration in visual acuity testing.