Contrast sensitivity and glare in patients with a diffractive multifocal intraocular lens.

Contrast sensitivity was measured in 25 patients who had a multifocal diffractive intraocular lens and in 23 control patients with a monofocal lens in four simulated light conditions: (1) daylight, (2) daylight with peripheral glare, (3) twilight, (4) twilight with central glare. In normal daylight and twilight, contrast sensitivity of the multifocal group was significantly lower than the control group's (P < .05). The difference was 0.13 log units for the multifocal group and 0.17 log units for the control group (mean value across the tested frequency from 1.5 to 18 cycles/deg). Peripheral glare reduced contrast sensitivity under daylight conditions in both groups (P < .05), but the loss did not differ significantly between the two (P > .05). Central glare reduced contrast sensitivity under twilight conditions in both groups (P < .05), with the greatest loss in the multifocal patients (P < .001). We conclude that the most significant loss of contrast sensitivity in patients with the diffractive multifocal intraocular lens is found with central glare under twilight conditions.