Aim: To describe vergence adaptation and how it may affect clinical practice.
Method: A literature-based essay is presented, which includes a review of published work over the last 7 years and older literature as appropriate.
Results: Vergence adaptation is a normal phenomenon which occurs in the presence of binocular single vision to induced concomitant and incomitant deviations. It may be affected by age and practice. It may mask larger deviations than those initially seen during clinical testing and may be of significance in the aetiology of some forms of strabismus.
Conclusion: Vergence adaptation has previously been acknowledged as being important in the maintenance of comfortable binocular vision. Consideration of the phenomenon is useful in explaining many observations seen during orthoptic practice.