Higher-order aberrations associated with better near visual acuity in eyes with aspheric monofocal IOLs

To investigate higher-order aberrations (HOAs) related to increased uncorrected near visual acuity in eyes with aspheric monofocal intraocular lenses.

All patients underwent phacoemulsification followed by implantation of aspheric monofocal intraocular lenses with a negative spherical aberration (Tecnis one-piece, ZCB00; Abbott Medical Optics, Inc., Milpitas, CA). The distance-corrected near visual acuity (DCNVA), corrected near visual acuity, uncorrected near visual acuity, corrected distance visual acuity, uncorrected distance visual acuity, defocus curve, and ocular and corneal HOAs were examined 1 month after surgery. All near visual acuity measurements were taken with a 4-mm external aperture after pharmacologic dilation. Eyes were divided into two groups according to the DCNVA: eyes with DCNVA of 0.4 logMAR (20/50 Snellen) or better (0.4 logMAR or better group) and eyes with DCNVA worse than 0.4 logMAR (0.4 logMAR or worse group). The HOAs for a 4-mm pupil between the two groups were compared.

A total of 37 eyes of 36 patients were included. The mean ocular spherical aberration was -0.010 ± 0.033 μm in the 0.4 logMAR or better group and -0.012 ± 0.023 μm in the 0.4 logMAR or worse group (P = .28). Among ocular HOAs, only vertical coma Z3(-1) showed a significant difference between the groups, with a mean ocular vertical coma of -0.038 ± 0.043 μm in the 0.4 logMAR or better group and 0.015 ± 0.061 μm in the 0.4 logMAR or worse group (P = .01). In corneal HOAs, no components showed a significant difference between the groups.

In cases of aspheric intraocular lens implantation, ocular vertical coma may be a major HOA associated with better near visual acuity. Although corneal aberrations are major determinants of ocular aberrations after cataract surgery, aberrations from internal optics may still play an important role in visual performance.