Anisometropic amblyopia in Macaca nemestrina monkeys produced by atropinization of one eye during development

Two macaque monkeys were reared with daily administration of the cycloplegic drug, atropine, to one eye until 8 months after birth. Behavioral testing of contrast sensitivity functions in the atropinized eyes during the rearing period demonstrated that this rearing procedure caused the treated eyes to be chronically defocused. Measurement at the age of 6 or 8 months of contrast sensitivity while optically correcting the defocus demonstrated that an amblyopia had developed in the treated eyes. Furthermore, the relative magnitude of the amblyopia across spatial frequencies was similar to the relative magnitude of the defocus. Subsequently testing at 1 year of age demonstrated that the deficits persisted for several months after termination of the defocus rearing. This rearing procedure appears to provide a reasonable primate model with which to study anisometropic amblyopia in monkeys.