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O Touzeau, C Allouch, VM Borderie, SE Scheer, T Bourcier, L Laroche; Comparison of Astigmatism Methods to Evaluate Variation of Astigmatism Induced by Penetrating Keratoplasty Suture Removal . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2075.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To evaluate different methods for assessing the change in astigmatism induced by penetrating keratoplasty suture removal.Methods:200 eyes of 195 patients with a clear corneal graft and no other ocular diseases were included. Subjective refraction was recorded just before and after all sutures were removed. Change in subjective astigmatism was calculated with different methods including simple subtraction method, algebraic subtraction method, rectangular coordinate methods (Holladay, Alpins), the law of the sines and cosines method (Naylor), matrix method (Long), polar analysis (Naeser), the trigonometric polar analysis (Cravy), and Russel method. Change in subjective astigmatism calculated by these methods was correlated with change in best spectacle-corrected visual acuity (LogMAR units). Results: The change in cylinder calculated by subtraction method showed the highest correlation with change in BSCVA (rs=0.66; p<0.001). The correlation was not significant for the algebraic subtraction method (rs=0.12; p=0.11). The correlation between change in BSCVA and change in astigmatism was lower for the other methods (rs =0.53-0.59; p<0.001). Conclusion: Subtraction cylinder method regardless axis is the best method to evaluate the change in astigmatism induced by penetrating suture removal. The change in astigmatism calculated by the other methods showed lower correlation with the change in BSCVA.
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