Optimum target refraction for highly and moderately myopic patients after monofocal intraocular lens implantation

Abstract

To determine the optimum target refraction for myopic patients who want to see at both near and intermediate distances without correction after cataract surgery. Hayashi Eye Hospital, Fukuoka, Japan. Sixty-nine eyes of 69 patients scheduled for phacoemulsification and monofocal intraocular lens (IOL) implantation were studied. The following age groups were recruited: 50s, 60s, and 70s. With addition of a spherical lens of 1.0, 1.5, 2.0, 2.5, or 3.0 diopters (D) after best distance correction (simulation of various degrees of myopia), visual acuity at various distances was measured using the all-distance vision tester. With the assumption that visual acuity of 20/30 is necessary for near and intermediate vision, the distances at which the mean visual acuity reached 20/30 were determined. Six patients did not have all examinations; thus, 24 patients in the 50s group, 23 in the 60s group, and 22 in the 70s group were included in the analysis. With simulation of -1.0 or -1.5 D of myopia, sufficient near visual acuity at 0.3 m was not obtained. With -2.0 D of myopia, visual acuity better than 20/30 was obtained at 0.7 m, 0.5 m, and 0.3 m. However, with -2.5 D of myopia, visual acuity reached 20/30 at 0.5 m and 0.3 m; with -3.0 D of myopia, it reached only 20/30 at 0.3 m. There were no significant differences between the age groups in mean visual acuity from far to near distances except for intermediate visual acuity with -1.0 D and -1.5 D of myopia and for near visual acuity with -2.5 D of myopia. Eyes with a monofocal IOL that simulates -2.0 D of myopia achieved sufficient visual acuity for both near and intermediate distances in 3 age groups. This indicates that -2.0 D is the optimum target refraction in myopic eyes.