• Serial measures (range, two to eight) of preferential-looking grating acuities of 52 infants with retinopathy of prematurity were made. Group 1 patients (n = 11), who had little or no macular displacement, had normal preferential-looking acuity except for two who had mild acuity deficits. None of the group 2 patients (n = 12), who had dragged maculas, ever had normal acuity. On the average, their acuities, which ranged from 1 to 6 octaves less than normal, gradually increased at a rate not significantly different from normal. Group 3 patients (n = 29), who had undergone open-sky vitrectomy, had significantly lower acuity despite reattachment of the retina.