The Maddox classification of vergence eye movements.

The classification of convergence as described by Maddox in The Clinical Use of Prisms is discussed. Maddox believed that the vergence system could be analyzed in terms of additive components designated according to their sensory origin: tonic vergence, accommodative vergence, reflex, or disparity (fusion), vergence, and proximal, or psychic, vergence. This description is brought into perspective with current-day descriptions of components of the binocular vergence system.