The development of grafting acuity was followed in 2 astigmatic primate infants one a human being and one a pigtail macaque monkey [Macaca nemestrina]. Both infants showed variations of acuity with grafting orientation, predictable from the orientation and type of astigmatism present. Optical correction of the human infant during testing virtually eliminated the variation of acuity with orientation, suggesting that a neurally based meridional amblyopia was not yet established.