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A Study to Compare Single Piece IOL (SN60WF) Vs. Multipiece IOL (MA30AC) in Accommodation Using Cycloplegic Auto Refraction

Ming Chen

Purpose: This study intend to determine which Acrysoft monofocal IOL between single-piece (SN60WF) and multipiece (MA30AC) is better in terms of accommodation and refractive stability using an objective techniques (Autorefractor) after 1% Tropicamide eye drops to relax ciliary muscle [1]. The better ability of accommodation in monofocal standard IOL will be better to apply to minimonovision (blended monovision) formula for presbyopia correction.
Method: This is a prospective randomized control study of 42 eyes implanted with SN60WF versus 43 eyes of MA30AC by a single surgeon. Both groups were Male 45%, female 55% and the same mean age of 76 years old. The mean post-op was 30 weeks. The refraction was done by Zeiss Autorefractor before cycloplegic drop (have instrument accommodation) and after cycloplegic drop (pharmacologically relax accommodation). The diopter change in spherical equivalent is considered as accommodation. The refractive data was converted to spherical equivalent and transferred to SPSS 16 for statistic study. Pair t-test and Independent t-test was done to compare the mean spherical equivalent. The Autorefractor can be suitable for objective measurement of accommodation was concluded in Win-Hall’s study.
Result: The paired t-test showed statistically significant change (P<0.01) in spherical equivalent of refraction before and after cycloplegic drop for both of the IOLs, mean change was -0.21D. (95% Confidence interval=-0.11 to- 0.30) The independent t-test to compare two IOLs showed significant more negative accommodative change after cycloplegic drop for MA30AC mean change was -0.74D ( P<0.01), versus SN60WF mean change was -0.39D ( P<0.03).
Conclusion: Since we used cycloplegic drops to relax the ciliary muscle, we expected that the refraction diopter change from before to after the drop should be plus if there were positive accommodation. In comparison to Pilocarpine drops to induce accommodation, the change in refraction should be in minus. There were negative accommodations for both IOL 30 weeks after surgery. However, it was more on the MA30AC (5.5 mm optic, 12.5 mm in length and 5 degree angulation) versus SN60WF (6.0 mm optic, 13.0 mm in length, no angulation). This matches other studies using different method of measuring accommodation. The accommodation more likely is a psudo accommodation rather than a psudophakic accommodation according to previous studies.