Influence of optic quality on contrast sensitivity and visual acuity in eyes with a rigid or flexible phakic intraocular lens

Purpose

To determine whether the difference in optic quality between 2 types of phakic intraocular lenses (pIOLs) affects visual quality.

Setting

Fundación Oftalmológica del Mediterráneo, Valencia, Spain.

Methods

Before implantation of a pIOL for myopia, all eyes had an examination including corrected (CDVA) and uncorrected (UDVA) distance visual acuity testing, corneal endothelial cell count (ECC), and intraocular pressure (IOP) measurement. The postoperative outcomes, determined at least 1 year after surgery, were CDVA; UDVA; contrast sensitivity function under photopic, mesopic, and mesopic with glare conditions; ECC; IOP; keratometry (Scheimpflug photography); and total ocular aberration (Hartmann-Shack aberrometry).

Results

Twelve eyes had implantation of an Artisan pIOL (rigid pIOL group) and 18 eyes, of an Artiflex pIOL (flexible pIOL group). The mean preoperative CDVA was 0.04 logMAR ± 0.01 (SD) in both groups (P>.5). The mean postoperative CDVA was 0.01 ± 0.02 logMAR in the rigid IOL group and 0.01 ± 0.06 logMAR in the flexible IOL group (P>.9). The photopic contrast sensitivity function was better with the rigid pIOL, and the mesopic contrast sensitivity function was slightly better with the flexible pIOL; however, neither difference was statistically significant.

Conclusions

Optic quality, measured by modulation transfer function and evaluated by average modulation, was approximately 13% better with the rigid pIOL than with the flexible pIOL. However, the difference was not enough to affect visual quality. At 1 year, the 2 groups had similar CDVA and contrast sensitivity function values, indicating that other optical or neural factors compensate for differences in optic quality.