Distance and near contrast sensitivity function after multifocal intraocular lens implantation

Abstract

Purpose To evaluate contrast sensitivity at distance and near after multifocal intraocular lens (IOL) implantation. Setting Ophthalmologic Institute of Alicante, University Miguel Hernández, 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.