AMERICAN OPTOMETRIC ASSOCIATION

® American pt i ssociation A. DESCRIPTION AND CLASSIFICATION Strabismus is a manifest deviation of the primary lines of sight of 1 prism diopter (PD) or more. This misalignment of the eyes can be classified as to: Direction (convergent, divergent, or vertical) Deviation equal or varying with the direction of gaze (comitant or incomitant) Frequency (constant or intermittent) Laterality (unilateral or alternating) Time of onset (congenital or acquired) Size (large, small, or intermediate) Involvement of accommodative system (accommodative or nonaccommodative) State of vergence system (convergence insufficiency or divergence excess, divergence insufficiency or convergence excess, basic esotropia or basic exotropia)