BACKGROUND: In eyes with conventional monofocal intraocular lenses (IOLs), uncorrected distance visual acuity (UDVA) deteriorates as myopic refraction error increases. This retrospective study aimed to evaluate tolerance to myopic residual refraction in eyes with conventional and enhanced monofocal IOLs. METHODS: Clinical records of 166 eyes from 135 patients with conventional monofocal IOLs (XY1, Hoya) and 55 eyes from 28 patients with enhanced monofocal IOLs (XY1-EM, Hoya) were reviewed. Associations between UDVA and refractive error spherical equivalent (SE) were evaluated using two analyses. The influences of UDVA on SE (0.0 logMAR or less, 0.1 logMAR, and 0.2 logMAR or higher) and the influence of SE on UDVA (within ± 0.50 D, between - 1.00 and 0.0 D, and - 1.00 D or less) were evaluated. In addition, changes in UDVA with SE were evaluated using segmented regression analysis, and SE break points were compared between IOL types. RESULTS: In the influences of UDVA on SE, the mean SE of eyes with XY1-EM was - 0.61 D for the range of UDVA of 0.1 logMAR, which was twice that of eyes with XY1 (P = 0.0025). In the influence of SE on UDVA, no differences were found. Segmented regression analysis resulted in the break point at -1.075 D in eyes with enhanced XY1-EM IOLs, whereas the break point was at -0.45 D in eyes with conventional XY1 IOLs. Both evaluation results showed the improvement of myopic refractive tolerances in the use of enhanced IOLs. CONCLUSIONS: The influence of myopic residual refractions on UDVA in eyes with conventional and enhanced monofocal IOLs was investigated. The quantitative evaluations revealed the improvement of refractive tolerance up to approximately - 1.00 D of myopia in eyes with enhanced monofocal IOLs. In addition, segmented regression analysis between UDVA and refractive error proved effective for evaluating refractive tolerance.
Yokogawa et al. (Thu,) studied this question.