Functional visual outcomes of cataract extraction in monocular versus binocular patients

Abstract

Purpose To determine the change in functional vision that occurs with cataract surgery in a group of monocular patients compared with a group of binocularly sighted control subjects. Design A retrospective case-control study. Methods Study subjects comprised 100 functionally monocular patients who underwent cataract surgery at the Jules Stein Eye Institute between 1996 and 2002. Control subjects were 100 binocularly sighted patients, matched to study subjects by age, sex, and timing of surgery. A single ophthalmologist performed all of the operations using an ultrasonic phacoemulsification technique. Best-corrected visual acuity (BCVA) was measured before and after surgery using a conventional visual acuity monitor. Self-reported visual function was assessed before and after surgery using the Visual Function 14 (VF-14) questionnaire. Paired t tests were used to report statistical significance. Results The monocular group had significantly worse mean BCVA than the binocular group before and after surgery, but the improvement experienced by the two groups was statistically indistinguishable ( P = .913). Mean global VF-14 score was significantly worse for the monocular than the binocular group before and after surgery, but the monocular group experienced a significantly greater improvement ( P = .00164) in VF-14 following surgery (20.4 points for the monocular group vs 10.1 points for the binocular group). Conclusions Monocular patients report twice as much improvement in functional vision as binocular patients despite similar BCVA gains. This may be because monocular patients had cataract surgery on their better-seeing eye, whereas binocular patients typically had surgery on their poorer-seeing eye.