Objective To compare the effectiveness of aspheric intraocular lenses(IOL) versus spherical IOL in the treatment of cataract. Method Randomized controlled trials comparing aspheric IOL with spherical IOL were identified by searching PubMed (2000 to October, 2008), EMbase (2000 to October, 2008), MEDLINE (2000 to October, 2008), and The Cochrane Library (Issue 3, 2008). Two reviewers independently assessed trials for eligibility and quality, as well as the extracted data. Data were synthesized using RevMan software (release 5) provided by the Cochrane Collaboration. Results A total of 14 trials (1383 eyes) were included for systematic review, and 11 out of 14 studies were included in the meta-analysis. Subgroup analyses were used according to different aberrations of aspheric IOL. The results showed a significant difference in the mean best corrected visual acuity at 3 months after cataract surgery in the AcrySof IQ IOL group with WMD -0.02, 95% CI -0.03 to -0.01(Plt;0.0001). It showed a significantly worse difference in the mean of the best corrected visual acuity at 3 months after cataract surgery in the AcrySof IQ IOL group with WMD –0.02, 95%CI –0.03 to –0.01 (Plt;0.000 1). It showed a significant worse in the mean the best corrected visual acuity in the Tecnis Z9000 IOL group with WMD 0.02, 95%CI 0.01 to 0.03 (P=0.002); and there was no significant difference between the two groups with WMD 0.00, 95%CI –0.02 to –0.03 (P=0.71). The results did display markedly less spherical aberration and total higher order aberrations than eyes implanted with the traditional spheric IOL in all subgroups (WMD –0.06, 95%CI –0.07 to –0.06, Plt;0.000 01, WMD –0.06, 95%CI –0.07 to –0.02, Plt;0.000 1, respectively). The majority of studies suggested significant improvement in the aspheric IOL group in contrast sensitivity, especially at mesopic low spatial frequencies, although some trials showed no significant difference. Conclusion The effectiveness of aspheric IOL is superior to spherical IOL during cataract surgery. No differences in aspheric IOL with different aberration are found in this series, and further study is required.
