The role of vergence adaptation in recovery of binocular single vision (BSV) following sensory strabismus.

Vergence adaptation is an important element of comfortable binocular single vision and probably contributes to the high incidence of orthophoria or small angles of heterophoria in the normal population. Where binocular single vision has been absent for a period of time, restoration of good visual acuity appears to enable the vergence adaptation mechanism to become active again. A case is presented in which a moderate to large angle of deviation rapidly 'disappeared' once good visual acuity was restored and the disparate images could be fused. Known factors concerning vergence adaptation are discussed in relation to such clinical cases.