The Effect of Darkness on the Miosis Associated with the Near Reflex

Julie Loughhead, Assoc.Dip.O. (Cumb), DOBA

Research was undertaken to investigate the pupillary constriction associated with the near reflex and to demonstrate the effect of darkness upon this reflex.

It was found that there exists a linear relationship between convergence and pupillary constriction and that this same relationship is present even in total darkness. It is suggested that it must be either proximal or voluntary convergence which is utilised in total darkness to initiate the miosis occurring on near fixation. The available evidence in literature supports this conclusion.