Four models of the effects of bilateral deprivation on longterm logMAR recognition acuity outcome: A. age at surgery has no effect on longterm visual acuity outcome, B. the earlier the surgery the better the longterm visual acuity outcome, C. there is an early window of time, beginning at birth, during which an optimal outcome can be attained but, if surgery is delayed beyond this window, longterm visual acuity outcome declines progressively, D. delay in surgery is associated with progressive decline in visual acuity outcome only during the first weeks of life, after which there is no further effect of duration.