In vivo measurement of longitudinal chromatic aberration in patients implanted with trifocal diffractive intraocular lenses

PURPOSE: To measure the longitudinal chromatic aberration (LCA) by both psychophysical methods and in vivo double-pass retinal imaging in patients bilaterally implanted with trifocal diffractive intraocular lenses (IOLs). METHODS: Measurements were performed with a polychromatic adaptive optics system provided with a supercontinuum laser, a Hartmann-Shack wavefront sensor, a deformable mirror, a motorized Badal system, a pupil monitoring system, a double-pass retinal imaging channel, and a psychophysical channel with monochromatically illuminated stimuli. Ten patients (20 eyes) bilaterally implanted with hydrophilic trifocal diffractive IOLs (POD F [FINeVision]; PhysIOL, Liege, Belgium) participated in the study. Measurements were performed in both eyes at three different viewing distances (0.00, +1.75, and +3.50 diopters [D]). Subjective best focus of monochromatic stimuli at five wavelengths (480 to 700 nm) was obtained using the Badal system. Best focused images of through-focus double-pass image series were obtained at three wavelengths (480 to 700 nm). LCA was computed from chromatic difference of focus curves (objective and subjective) as the difference between 480 and 700 nm at near, intermediate, and far. RESULTS: The average subjective LCA was 0.82 ± 0.05 D for far, 0.27 ± 0.15 D for intermediate, and 0.15 ± 0.15 D for near. The average objective LCA was 0.72 ± 0.10 D for far, 0.19 ± 0.15 D for intermediate, and 0.07 ± 0.17 D for near. CONCLUSIONS: Objective LCA was lower than subjective LCA, which was in agreement with previous studies on patients with phakic and monofocal IOLs. In vivo measurements of LCA enable understanding of the relative contribution of refractive and diffractive LCA and will eventually optimize IOL designs to improve polychromatic image quality.