Lack of positive results of a physiologically based treatment of amblyopia

Recent reports have described marked improvement of visual acuity in amblyopic eyes of young children following monocular exposure to square-wave gratings presented at a variety of spatial frequencies and orientations for as little as 7 minutes. We sought to confirm and expand on these investigations, with emphasis on single-session results. Sixteen juvenile and 11 adult amblyopes and 26 control subjects were used. Visual acuity was determined before and after a 7-minute stimulation period using an E-chart that controlled for contour interaction. The 50% visual acuity threshold corrected for guessing was computer calculated by probit analysis. Results show that frequency, range, and magnitude of changes (either increases or decreases) in visual acuity following stimulation were approximately the same (< +/- 10% Snell-Sterling) in both amblyopic and control groups. These findings suggest that brief exposure to the grating patterns had little if any beneficial effect on visual acuity in amblyopic eyes.