Purpose
To evaluate optical performance of an asymmetric refractive multifocal intraocular lens (MIOL) using a visual simulation system.
Methods
The system consists of a lens that corresponds to a cornea, an IOL in a water cell, and a charge-coupled device (CCD) camera. The images formed by the lens can be detected by the CCD camera and observed on the monitor of a personal computer. The aperture diameter is exchangeable in the water cell. Using this system, visual simulations of Landolt visual acuity (VA) charts at various distances were performed using the MIOL (LENTIS® Mplus, Oculentis) through a 3.5-mm aperture corresponding to photopic conditions or a 4.5-mm aperture corresponding to mesopic conditions. The contrasts of the gaps of large (logarithm of the minimum angle of resolution [logMAR] 0.7), medium (logMAR 0.4), and small (logMAR 0.0) Landolt VA charts in the simulated images were analyzed using Photoshop graphics editing software (Adobe).
Results
Using the 3.5-mm aperture, the contrasts of the gaps of the large, medium, and small charts were 0.22, 0.1, and 0.08 at 5 meters (m) and 0.08, 0.04, and 0.02 at 0.34 m, which was the best near focus, respectively. Using the 4.5-mm aperture, the contrasts of the gaps of the large, medium, and small charts were 0.14, 0.07, and 0.03 at 5 m and 0.07, 0.04, and 0.01 at 0.34 m, respectively. The large charts maintained good contrast at all distances through the 3.5-mm aperture. The contrast decreased with decreasing sizes of the Landolt rings, especially at the intermediate distance (from 1-0.5 m). Through the 4.5-mm aperture, the results showed a similar trend with degraded contrasts compared to the 3.5-mm aperture. The typical simulated image had an asymmetric blur probably due to the asymmetric MIOL design.
Conclusions
The asymmetric refractive MIOL provides good optical performance at all distances for large charts under photopic conditions, although the optical performance degrades especially at intermediate distance with medium and small charts or under mesopic conditions.
Keywords: 567 intraocular lens •
467 clinical laboratory testing •
684 refractive surgery: optical quality