Vergence adaptive changes with varying magnitudes of prism-induced disparities and fusional amplitudes.

Vergence adaptation response monitored with various prism disparities demonstrated that the rates of adaptation decreased as the prismatic effect was increased. However, the amount adapted increased with the increase in the value of the prism until this value fell outside the fusional amplitude; the amount adapted then decreased. However, a large disparity can be adapted to with ease if the prismatic effect is increased gradually in small steps. The clinical implications of these results are discussed.