Clinical Evaluation Of Correction Of Corneal Astigmatism In Femtosecond Laser Assisted Cataract Surgery(FLACS)

Objective:To evaluate the correction of corneal astigmatism during femtosecond laser assisted cataract surgery(FLACS)via femtosecond laser assisted astigmatic keratotomy(FSAK)using the nomogram modified by our research team.Method:This study included 49 patients(66 eyes)who underwent FLACS in the Department of Ophthalmology of Xiangya Hospital affiliated to Central South University between October 2017 to January 2022.All patients underwent FSAK using the nomogram modified by our research team during FLACS.Keratometric astigmatism was evaluated via Pentacam before and after surgery.Patients were followed up 1 week,1month,3 months,3 years after operation.Keratometric astigmatism,uncorrected long distance visual acuity,best corrected long distance visual acuity,defocus curve and objective visual quality analyzed via Optical Quality Analysis System was recorded.Vector analysis using Alpins method and Spearman correlation analysis were performed to evaluate the astigmatic changes in different groups.Result:The mean preoperative astigmatism was 1.50±0.52 D,the mean residual astigmatism at the last follow up was 0.61±0.42D(P<0.01).The proportion of corneal astigmatism less than 1.0D increased from 27.3%preoperatively to 84.9% postoperatively,and the proportion of corneal astigmatism less than 0.5D increased from 0% preoperatively to 59.1%postoperatively.The magnitude of error at 1week,1 month,3 months,3years postoperatively was-0.23±0.70 D 、 0.01±0.63 D 、 0.07±0.48 D 、0.05±0.53 D respectively.The correction index was 1.15±0.66、0.96±0.55、0.89±0.45、0.89±0.37 respectively,no significant difference was found between the groups(P > 0.05),demonstrating a highly predictable astigmatism correction effect,and slight undercorrection after stabilization.The angle of error at each follow up time point was very close to 0°,indicating no significant systematic error of misalignment.The absolute angle of error at each follow up time point was13.97±16.38°,9.44±8.81°,9.61±8.24°,8.36±5.44° respectively,suggesting variable factors such as incision healing at an individual level.At the last follow-up,81.3% of the subjects had an uncorrected long distance visual acuity better than 0.8,and 72.7% of the subjects had a MTFcutoff greater than 30 c/deg.Conclusion:FSAK during FLACS using the nomogram modified in this study,can effectively correct corneal astigmatism with strong predictability,fair stability and accuracy.Misalignment at an individual level may reduce the effectiveness of this method.Astigmatism correction is effective at 1week,and remains stable from 3 months to 3 years postoperatively.The postoperative visual quality is high and stable.