PURPOSE: To evaluate the effect of partial corneal spherical aberration (SA) correction in an intraocular lens (pIOL) compared with a neutral SA monofocal IOL (B+L enVista, EE) on the simulated defocus curves using a physiological model eye.

METHODS: A 20.0 D enVista EE monofocal IOL was modified by optimizing the posterior surface aspheric coefficients in Ansys Zemax to partially compensate an ISO2 cornea with +0.20 µm of spherical aberration (pIOL design). Through-focus performance was evaluated using a modified Liou-Brennan model eye by placing a paraxial surface 12 mm anterior to the corneal vertex to simulate defocus. Three levels of physiological corneal spherical aberration—0.00 µm, 0.27 µm, and 0.55 µm at a 5.15-mm IOL pupil—representative of the normal population were modeled by adjusting the anterior corneal conic constant. Simulated visual acuity (VA) was derived from the area under the modulation transfer function (aMTF) curve using a previously published method. All VA simulations were performed for a 3.0-mm IOL pupil aperture.

RESULTS: Peak predicted visual acuity remained similar across all spherical aberration conditions for both the EE and pIOL design. The overall through-focus profiles of the two lenses were likewise comparable, with only subtle differences between them. In eyes modeled with average and high physiological corneal SA, the EE lens exhibited a modest enhancement in intermediate-near performance; however, the magnitude of this effect fell within the standard deviation of the clinical data and is unlikely to be clinically meaningful. Additionally, the peak simulated VA varied across the different corneal SA conditions, suggesting that physiological spherical aberration may contribute to variability in refractive outcomes among patients.

CONCLUSIONS: Under physiological conditions, altering the level of induced corneal spherical aberration did not confer an intermediate-vision advantage for the partially compensating IOL and, if anything, favored the neutral SA design. The observed shifts in best-focus position across corneal SA conditions highlight the importance of accounting for individual corneal spherical aberration when determining IOL power for both designs.