Abstract
Purpose :
To evaluate the impact of posterior astigmatism on outcomes with non-toric intraocular lens (IOL) implantation and compare the astigmatism prediction error using Barrett formula and Galilei Dual Scheimpflug Analyzer.
Methods :
Cornea astigmatism was measured with 3 different modalities before cataract surgeries, including auto-keratometry, IOLMaster (Carl Zeiss Meditec, Jena, Germany), Galilei Dual Scheimpflug Analyzer (Zeimer Ophthalmic System AG, Port, Switzerland); pre-operative corneal astigmatism was further processed with Barrett toric calculator for predicted residual astigmatism (PredRA). Phacoemulsification with non-toric IOL implantation was performed in 51 eyes with mild to moderate corneal astigmatism (range, 0 to 3.5 diopters (D)). The actual corneal astigmatism was calculated based on manifest refractive astigmatism 1 month postoperatively with consideration of individual surgical induced astigmatism. The error in PredRA was determined by difference of postoperative subjective refraction and PredRA using vector analysis.
Results :
The centroid errors in PredRA were with-the-rule (WTR) with IOLMaster (0.31D) and lower with auto-keratometry (0.24D). The Barrett toric IOL calculator with IOLMaster measurement had lowest PredRA (0.21D, P<.001). While Galilei Dual Scheimpflug Analyzer demonstrate relative high centroid error (SimK, 0.53D; total corneal power, 0.45D) and absolute error in PredRA. We also found significant correlations of pre-operative corneal astigmatism with prediction accuracy by Galilei Dual Scheimpflug Analyzer (Spearman correlation coefficient r = 0.477, P = .008).
Conclusions :
For relative low astigmatism in our study, Galilei Dual Scheimpflug Analyzer performed poorly in prediction of astigmatism error. Barrett-adjusted IOLMaster measurement is still appropriate method for adjustment of posterior astigmatism in low corneal astigmatism.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.