Source: CATARACT & REFRACTIVE SURGERY TODAY – FEBRUARY 2006

FACTORS INFLUENCING MONOVISION’S SUCCESS

Patients’ Expectations

The goal of monovision is to increase patients’ functional vision for daily tasks without the aid of glasses.
This endpoint, however, does not preclude a person’s ability to use glasses for tasks requiring clear binocular distance vision (ie, night driving) or sharp binocular near vision (ie, prolonged reading). Although some patients are satisfied with monovision, they face disadvantages such as less-than-ideal distance vision; the possible need for glasses when driving at night; two eyes, each focusing differently; and the adjustment involved with this form of correction.1-4

Ocular Dominance and Interocular Blur Suppression

Interocular blur suppression is essential to successful monovision. In each person, the input from one eye or the other is usually dominant in influencing binocular cells in the cerebral cortex. Information from an individual’s dominant eye produces a greater response to a given stimulus than input from his nondominant eye. Correcting the dominant eye for distance and the nondominant eye for near is standard, because (1) correcting the dominant eye for the most commonly used viewing distance maximizes blur suppression and (2) the dominant eye maximizes the performance of visual tasks requiring spatial perception.4

Although this approach is the norm in the studies reviewed for this article, Jain et al 4 reported that 43% of 42 study patients were treated with crossed monovision (wherein the dominant eye is corrected for near), and subjects’ satisfaction ranged from 72% to 86%. Although this range was relatively high, it was the lowest rate of patient satisfaction among the studies reviewed herein.