Correlation between optics quality of multifocal intraocular lenses and visual acuity

PURPOSE: To study the relationship between the optics quality of multifocal intraocular lenses (IOLs) and distance-corrected near, intermediate, and distance visual acuity to determine the degree to which optics quality must change to produce a significant difference in visual acuity. SETTING: Fundación Oftalmológica del Mediterráneo, Valencia, Spain. METHODS: Monocular distance-corrected visual acuity (decimal and logMAR) was measured at 4 m, 70 cm, and 30 cm under photopic and mesopic conditions in eyes with 1 of 3 multifocal IOL models. Visual acuity versus the "average modulation" of the IOL was assessed. RESULTS: The pupil diameter and patient age were similar between the 3 IOL groups (20 eyes each). A difference in average modulation (ie, optics quality) up to 15% did not produce significant differences in mean visual acuity between 2 groups; however, there was a significant difference in mean visual acuity between 2 groups when the average modulation values differed by at least 25%. The slope of the linear correlation between visual acuity and average modulation was 0.018 (r(2) = 0.91) under photopic conditions and 0.024 (r(2) = 0.089) under mesopic conditions. CONCLUSIONS: There was a strong linear correlation between IOL optics quality and visual acuity with distance correction under photopic conditions with a pupil of approximately 3.5 mm in a cohort in which the patient age was controlled. The correlation was similar under mesopic conditions. The eye's tolerance to modulation transfer function decay was approximately 15% of the average modulation value.