Effects of chronic atropinization on visual acuity in kittens.

Atropine was instilled daily from the time of eye-opening until 14 weeks of age into either one or both eyes of developing kittens. Following a 4 week recovery period, grating visual acuity was determined using behavioral techniques under both monocular and binocular viewing conditions. The monocularly treated kittens behaviorally demonstrated an amblyopia in the treated eye and an absence of binocular summation. In contrast, the binocularly treated kittens appeared to show normal visual acuity in both eyes and their performance improved during binocular viewing conditions. Single-unit recordings in striate cortex indicated that binocular atropinization did not alter cortical binocularity, however, monocular atropinization resulted in a decrease in the proportion of binocularly excited neurons and a shift in ocular dominance to the untreated eye.