Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients

AIM: To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laser assisted phacoemulsification (FLACS). METHODS: This study enrolled patients with cataract combined with regular corneal astigmatism of >0.75 D, who underwent FLACS. Symmetrical arc incision was set at 8 mm diameter and 85% depth. The follow-up time was 3-24mo (4.92 +/- 3.49mo). Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation. The changes in corneal astigmatism were analyzed by Alpins method. The correlation of astigmatism type, age, corneal horizontal diameter, corneal thickness, arc incision length, and correction index (CI) was analyzed, and the residual corneal astigmatism was compared with the residual whole eye astigmatism. RESULTS: Totally 79 patients (102 eyes) were enrolled, 10 patients had corneal epithelial injury, 1 patient occurred corneal epithelial hyperplasia. The corneal astigmatism was 1.23 +/- 0.38 D pre-operation, and decreased to 0.76 +/- 0.39 D post-operation (t=10.146, P=0.000). Corneal high-order aberration was 0.17 +/- 0.08 mu m pre-operation and 0.24 +/- 0.11 mu m post-operation (t=-5.186, P=0.000). The residual corneal astigmatism and residual whole eye astigmatism were no significant difference (t=-0.347, P=0.729). Using Alpin's method, the following were determined: target-induced astigmatism (TIA) =1.23 +/- 0.38 D, surgery induced astigmatism (SIA) =0.77 +/- 0.45 D, difference vector (DV)=0.77 +/- 0.39 D, and CI=0.54 +/- 0.28. Age, astigmatism size, corneal horizontal diameter, corneal thickness, and arc incision length were not correlated with CI. The CI for against the rule astigmatism (ATR) was better than that for with the rule astigmatism (WTR; P=0.001). CONCLUSION: Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR, but increase higher-order corneal aberration. CI is not ideal, it's not a perfect choice if we pursue ideal correction effect.