Contrast sensitivity with monofocal and bifocal intraocular lenses

Bifocal intraocular lenses (BIOLs) reduce image contrast. We measured contrast sensitivity (CS) to evaluate the clinical significance of the loss in image contrast. Four groups were compared: 15 patients with a monofocal IOL, 13 with the True Vista BIOL, 13 with the AcuraSee BIOL, 11 with the diffractive BIOL. CS was measured using the Mentor B-VAT II-SG. Distance CS was slightly better in monofocal eyes than in all bifocal eyes, and distance CS was considerably better than near CS in eyes with the True Vista or the AcuraSee BIOL. With the diffractive BIOL, values were about the same at distance and near focus. Our results demonstrate that BIOLs reduce CS. thereby performing differently: both True Vista and AcuraSee favor distance vision, while the diffractive BIOL provides about the same contrast at distance and near focus.