Visual function with presbyopic contact lens correction.

All forms of ophthalmic correction for presbyopia require compromises in viewing flexibility and visual function. The unique effects on vision of contact lenses used in managing presbyopia are especially intriguing and potentially problematic. Bifocal contact lenses produce unique changes in the nature and quality of the retinal image. In monovision (MV) correction, anisometropia is intentionally created by fitting one eye to see clearly at optical infinity and the other eye to see clearly at the near working distance. Our review of the literature indicates that most visual functions are affected by these departures from the conventional optical correction strategies used on nonpresbyopes. Sensory functions such as contrast sensitivity and stereoacuity are affected most, whereas motor functions such as convergence and accommodation are not noticeably impaired. MV appears to produce a more widely acceptable visual compromise than currently available bifocal contact lenses for most patients.