Effect of decentration or rotation of wavefront–guided IOLs on the higher–order aberrations of the eye

Abstract

Abstract: : Purpose: To evaluate the theoretical effect of decentration or rotation of wavefront–guided IOLs on spherical aberration (SA), coma, and total higher–order aberrations (HOAs, 3^rd–6^th order) of the eye (6–mm pupil). Methods: The study consisted of 3 portions, all involving theoretical calculations of effects of decentration or rotation of wavefront–guided IOLs: 1) we analyzed the effect on HOAs of decentration (0.25 mm interval up to 2.0 mm) of an aspherical IOL (ASIOL) (SA of –0.25 µm with 6–mm pupil); 2) the theoretical effect of decentration of the ASIOL in 154 eyes aged between 40 to 80 years was evaluated; residual HOAs were calculated by adding HOAs from the ASIOL to the corneal HOAs calculated from corneal topographic data (Humphrey) using CTView program (Sarver and Associates, Inc., Merritt Island, FL); the effect of decentration of the ASIOL was analyzed by comparing the residual HOAs with centered ASIOL to the HOAs with decentered ASIOL; and 3) residual HOAs were investigated when a wavefront–guided IOL (WAIOL) with aberration correction up to 6^th order was decentered or rotated (5° interval up to 30°) in the 154 eyes. Results: 1) Coma was the only significant aberration induced by a decentered ASIOL. With an ASIOL (SA: –0.25 µm), the induced coma was 0.13 µm, 0.27 µm, 0.40 µm and 0.53 µm for decentration of 0.25 mm, 0.5 mm, 0.75 mm and 1 mm, respectively; 2) the mean corneal HOA was 0.506 µm, and the residual HOA was 0.415 µm if the ASIOL was perfectly centered. Although coma was introduced when the ASIOL was decentered, the residual SA was reduced; the total HOAs were consistently lower than corneal HOA if the decentration was less than 0.5 mm; and 3) residual HOAs with decentered or rotated WAIOL will be reported. Conclusions: Implantation of an aspherical IOL reduces HOA if the decentration of the IOL is less than 0.5 mm.

Keywords: optical properties • cataract