Suppression behavior analyzed as a function of monovision addition power.

Monovision, the use of a monocular addition for near viewing, is a clinical technique sometimes used to correct presbyopia. This technique attempts to maintain binocular function while requiring a degree of central suppression. We examined suppression behavior in spectacle monovision as a function of addition power. Suppression behavior was determined by measuring the length and frequency of periods of suppression for a range of monocular addition powers. Testing was conducted at viewing distances of 6 m and 40 cm. The most striking result is the existence of a near/distance differential: the monocular addition power required to stabilize suppression at near is greater than at distance. It was also found that suppression behavior may be stable even in the presence of a relatively high level of stereoscopic acuity. The relation between the contradictory needs for suppression and binocular functioning under monovision conditions is discussed.