Optimal amount of anisometropia for pseudophakic monovision.

PURPOSE To determine the optimal target anisometropia for pseudophakic monovision. METHODS Thirty-five bilaterally pseudophakic patients who received monofocal intraocular lenses were included in the study. Binocular corrected distance visual acuity (CDVA) and binocular distance-corrected near visual acuity (DCNVA) and stereoacuity were measured after simulating 1.00, 1.50, and 2.00 diopters (D) of monovision by adding the appropriate spherical lens to the nondominant eye. We presumed that mean binocular DCNVA of 20/40, binocular CDVA of 20/25, and stereoacuity <100 seconds of arc (arc sec) were necessary for successful monovision. RESULTS With no anisometropia, mean binocular DCNVA was 20/97, binocular CDVA was 20/20, and mean stereoacuity was 71 arc sec. With 1.00 D of monovision, mean binocular DCNVA was only 20/60, although binocular CDVA and mean stereoacuity were sufficient. With 1.50 D of monovision, binocular DCNVA was 20/38, binocular CDVA at other distances exceeded 20/21, and stereoacuity was 100 arc sec, which was a 29-arc sec reduction. With 2.00 D of monovision, binocular DCNVA reached 20/31, but stereoacuity was 158 arc sec, which was an 87-arc sec reduction. The number of patients who met the criteria for successful monovision was significantly greater with 1.50 D of monovision than with 1.00 or 2.00 D of monovision (P=.0134). CONCLUSIONS Pseudophakic monovision with anisometropia of 1.50 or 2.00 D provides useful binocular visual acuity from far to near. However, because stereopsis with 2.00 D of monovision is substantially impaired, approximately 1.50 D of anisometropia is thought to be optimal for successful monovision.