The development of accommodation.

We investigated the roles that blur, proximity and vergence cues play in the development of accommodation. Accommodative responses to targets incorporating one or more of these cues were measured for four adults and eight infants at 1.5 and 3 months of age using eccentric photorefraction. Adults showed accurate accommodation to blur cues, and variable accommodation with proximity cues alone. Some infants at both ages showed fixed accommodative responses to all stimulus conditions. Others responded consistently in the correct direction for pattern targets at different distances, but made poorer responses when blur was presented in conflict with distance. Binocular viewing improved the accommodative responses in only some infants.