Population study of fixation disparity, heterophoria, and vergence.

Data on phorias, vergences, and fixation disparities were gathered for distant and near viewing conditions from a nonclinical, young adult population. Normative values were computed from the data for analysis and comparison. Our study revealed slightly less exophoria at far and near than Morgan's study, together with large base-out vergence readings. We found proportionately more esophores with exo fixation disparity who require base-in prism to neutralize the fixation disparity than Ogle's studies found.