Simulating Healthy And Keratoconic Corneal Profiles In Model Eyes To Evaluate Intraocular Lens Performance

Laboratory analysis of intraocular lenses (IOLs) allows an objective characterization of each lens in a controlled environment, providing an optimal setting for direct comparison of their optical performance. In this experimental study, we computed the corneal tomography data of a healthy and a keratoconic eye into our customized model eye featuring three different extended-depth-of focus (EDOF) IOLs and compared their image quality metrics.

The David J. Apple International Laboratory

A healthy and a keratoconus eye was selected for a retrospective review. Surface Zernike coeffcients derived from their corneal tomography (Pentacam) were imported to Nimo Tempo (Lambda-X), an interferometry-based automatic metrology device that captures the full wavefront and diffractive profiles of IOLs and enables advanced simulation to assess the overall optical quality. Three extended-depth-of-focus (EDOF) and a monofocal IOLs were analysed at 3-mm pupil under three conditions: 1) a standardized optical condition that only accounts for spherical aberration, 2) a normal eye with natural aberration levels, and a 3) mild keratoconus. The average modulation transfer function (MTF) was calculated at spatial frequencies from 1 to 50 lp/mm.

Under standardized optical conditions, the ZCB00 showed the highest MTF (0.87) at primary focus, followed by the ICB00 (0.85) and PureSee IOLs (0.62). The model eye with natural aberrations led to 26%, 34%, and 32% decrease in MTF for ZCB00 (0.64), ICB00 (0.56), and PureSee (0.42) IOLs at far focus, respectively, while the Symfony lens demonstrated 27% and 20% MTF reduction at its primary (0.37) and secondary (0.37) peaks. In keratoconus eye model, average MTF decreased in all lenses, with 57%, 56%, and 50% decrease for ZCB00 (0.37), ICB00 (0.37), and PureSee (0.31) IOLs at far focus, respectively. The Symfony lens demonstrated less reduction in its average MTF, with 45% and 46% decrease at its primary (0.28) and secondary (0.25) peaks.

The MTF values measured in standardized optical conditions demonstrated good performance of the studied IOLs, which was only mildly affected by the natural level of higher-order aberrations. Both EDOF and monofocal IOLs experienced loss of average MTF in a mild keratoconus eye model, reflecting the impact of irregular corneal astigmatism on the overall optical quality. Further analyses assessing the efficacy and tolerance of toric IOLs in keratoconus eye models may help quantify their superiority to non-toric lenses.