A comparison of visual performance between a rigid PMMA and a foldable acrylic intraocular lens

Purpose To examine post-operative visual outcomes when using micro-incision surgery and a three-piece, foldable acrylic intraocular lens (IOL) and whe n using small-incision surgery and a one-piece, rigid polymethylmethacrylat e (PMMA) IOL,. Methods Phacoemulsification and IOL implantation was conducted by one surge on on 86 subjects (aged 50-89 years) with cataracts. Of these subjects, 67 completed the study. Subjects were implanted either with a foldable IOL (n = 38) or a rigid IOL (n = 29), Best corrected Snellen visual acuity and con trast sensitivity (2-28 cycles/degree) were measured approximately 2 months postoperatively. Comparisons were made between the pseudophakic groups and an additional group of 28 age-matched, normal subjects (aged 58-81 years). Non-parametric (Kruskal-Wallis and Mann-Whitney U) as well as parametric ( ANOVA and Pearson) statistics tests were used in the analysis of results. Results All pseudophakes had corrected visual acuity of 6/9 or better. Ther e were no significant differences in visual acuity (Kruskal-Wallis, p = 0.6 1) or contrast sensitivity (ANOVA, p = 0.33) between the three groups. The mean residual refractive error of the foldable IOL group was hypermetropic in comparison with the rigid IOL group but not significant at the 99% level of probability (Mann-Whitney U, p = 0.02). There was no significant differ ence in astigmatism between the groups. Conclusions Implanting a foldable acrylic IOL gave no post-operative benefi t in visual acuity and contrast sensitivity to pseudophakes over a less exp ensive rigid PMMA IOL, within this post-operative period. This study did no t provide a comparison between the two lenses regarding post-operative comp lications, in particular the important long-term complication of posterior capsular opacification (PCO). Until and if any particular advantage of a gi ven IOL in reduced incidence of PCO is confirmed, it appears more economica l to implant the conventional rigid PMMA IOL using small-incision surgery.