Abstract: Objectives To evaluate degrees and percentages of cyclorotation in Chinese patients during femtosecond laser assisted cataract surgery performed by using LenSx femtosecond laser platform and to further sub-analyze bilateral cases to assess the congruency between both eyes. Methods This was a single-centre retrospective study(Beijing AIER-Intec Eye Hospital, Beijing, China)in which the records of 330 eyes of 274 patients who underwent femtosecond laser-assisted cataract surgery in 1 or two eyes(with placement of posterior chamber IOL)between May 2017 and July 2019 by using femtosecond laser platform(LenSx)were reviewed.LenSx Femtosecond Laser(Alcon Laboratories, Inc, Fort Worth, Texas, USA)was used to carry out corneal incisions, anterior capsulotomies and lens fragmentation in this procedure. All the patients were marked on corneal limbus(at 3 and 9 o’clock positions)by using sterile skin marker(Medplus.inc)while sitting upright preoperatively. Percentages of cyclorotation were calculated. Absolutes values were taken for all calculations. The cyclorotation data was tested to determine whether it followed a normal distribution. Descriptive statistics were applied to calculate percentile values of cyclorotation which is presented as(M ［P25; P75］). Results This retrospective study evaluated 330 eyes of 274 Chinese patients who had femtosecond laser-assisted cataract surgery using the femtosecond laser platform. Of the 330 eyes, there were 90 eyes(27.27%)that did not show cyclorotation. Out of 330 eyes that were analyzed, 72.72%(240 eyes)exhibited cyclorotation. The median value of cyclorotation was 3.0［0.0; 5.0］(ranged between 0 to 19 degrees). Of the 330 eyes, there were 90 eyes(27.27%)that did not show cyclorotation. Overall anticlockwise rotation(172 eyes, 52.12%)was more common than clockwise rotation(68 eyes, 20.60%).The total numbers of right and left eyes were 169 and 161 respectively. In terms of laterality, 43.78% of right eyes(74 eyes out of 169)and 60.86% of left eyes(98 eyes out of 161)showed anticlockwise rotation. 25.44% of right eyes(43eyes)and 15.52% of left eyes(25 eyes)exhibited clockwise rotation. Therefore anticlockwise rotation was considered as common occurrence in both left and right eyes. In order to assess the congruency of cyclorotation between eyes in bilateral cases, a subanalysis of all the patients who underwent bilateral femtosecond laser-assisted cataract surgery(56 out of 274)was performed. In total, 17 patients exhibited incylorotation(both eyes moved nasally)and 4 patients showed motion of eyes temporally exhibiting excyclorotation. In rest of patients some of them showed no rotation and others exhibited the movement of both eyes in opposite direction(one eye nasally and other temporally and vice versa).There were no AK-related complications or complications during femtosecond laser-assisted cataract surgery. Among them 56 were bilateral cases. Conclusion Clinically significant cyclorotation can occur during femtosecond laser assisted cataract surgery causing axis misalignment which might influence the desired astigmatism correction outcomes. It is highly recommended to take crucial compensatory measures to address this problem.

Key words: Femtosecond Laser, Cataract, Cyclorotation, Clockwise rotation, Anticlockwise rotation