Distance and near contrast sensitivity function after multifocal intraocular lens implantation

Purpose: To evaluate contrast sensitivity at distance and near after multifocal intraocular lens (IOL) implantation. Setting. Ophthalmologic Institute of Alicante, University Miguel Hernandez, Alicante, Spain. Methods: Contrast sensitivity was measured with the Stereo Optical Functional Acuity Contrast Test at distance and near in 21 patients with a refractive multifocal IOL (Array SA-40N, AMO). A control group with a monofocal IOL (SI-40NB, AMO) was also studied to allow comparison of results. Contrast sensitivity was measured 1, 3, 6, 12, and 18 months after IOL implantation. Results: There was a statistically significant greater reduction in contrast sensitivity at distance at all spatial frequencies in the multifocal group than in the monofocal group during the first month. At 3 months, contrast sensitivity at 12 and 18 cycles per deg remained reduced in the multifocal group; contrast sensitivity at the other frequencies did not differ from that in the monofocal group (P>0.1). At 6, 12, and 18 months, contrast sensitivity at all spatial frequencies was not significantly different between groups (P>0.1). There was a statistically significant greater reduction in near contrast sensitivity in the multifocal group than in the monofocal group at all spatial frequencies during the first and third month after surgery (P<.01). No statistically significant differences were found between groups after 6 months (P>0.1). Contrast sensitivity at distance and near in the multifocal group improved over time (P<.01). Conclusions: The Array IOL provided contrast sensitivity at distance comparable to that obtained with the monofocal IOL between 3 and 6 months after implantation. Near contrast sensitivity improved over time but was always lower than at distance and in the monofocal near-corrected patients, which is acceptable to avoid near visual function degradation.