Short-term Rotational Stability And Its Related Factors Of Toric Intraocular Lenses

Purpose:To evaluate the short-term rotational stability of toric intraocular lenses(IOLs)and analyze its correlation with preoperative and intraoperative measured parameters.Methods:This retrospective study enrolled 50 eyes from 44 cataract patients who underwent toric IOL implantation at the Eye Center,the Second Affiliated Hospital of Zhejiang University during July 2016 to February 2017.Preoperative biometric parameters including corneal astigmatism using Pentacam scheinpflug imaging system,axial length(AL)and lens thickness(LT)using A-scan ultrasound,anterior chamber depth(ACD)and sulcus-to-sulcus(STS)using anterior segment optical coherence tomography(AS-OCT).The area of capsulorhexis was measured with rhinoceros 5.0 software on the surgery image.The follow-up examinations,including residual astigmatism(RAS)and the postoperative toric IOL axis assessed by anterior segment photograph,were performed at 1 month after surgery.Correlation analysis was employed between rotational stability and factors like ACD?STS?AL?LT?the area of capsulorhexis and target toric IOL axis.Statistical data were analyzed using SPSS 21.0 software with Pearson linear correlation analysis.The difference was considered as significant when P<0.05.Results:Before toric IOL implantation,the preoperative mean value of uncorrected distance visual acuity(UDVA;logarithms of the minimal angle of resolution(logMAR)),ACD,horizontal STS,horizontal keratometer,vertical keratometer,corneal astigmatism,LT,AL,were 0.98±0.471ogMAR,2.74±0.38mm,11.79±0.86mm,43.68±1.56D,45.37±1.68D,1.69±0.85D,4.62±0.73 mm,24.93±2.41mm.Of the 50 eyes analyzed,36.00%had high myopia.The intraoperative mean value of toric IOL diopter,target toric IOL axis,the area of capsulorhexis were 19.94±3.13D,64.00±52.48°,26.31±3.04 mm2.The postoperative mean value of corrected distance visual acuity(CDVA;logMAR)was 0.0624±0.0819 logMAR,with 46.00%of eyes achieved 0 logMAR and 86.00%of eyes within 0.10 logMAR.The postoperative mean value of RAS was-0.86±0.88D,with within-0.50D and-1.00D in 40.00%and 72.00%of eyes,respectively.The mean absolute rotation of toric IOL at 1 month was 4.26±2.95°(0°-15°),with within 5.0°and 10.0° in 74.00%and 96.00%of eyes,respectively.The direction of rotation was clockwise in 74.00%of eyes,counter-clockwise in 24.00%of eyes and 2.00%with no rotation.According to Pearson linear correlation analysis,the Pearson's r of LT,AL,ACD,horizontal STS,target toric IOL axis were 0.131,0.030,0.020,0.05,0.016,and the P value were 0.370,0.838,0.893,0.545,0.912.There was no statistically significant relation between above measured parameters and postoperative rotational stability.On the other hand,toric IOL rotation was positively correlated with the area of capsulorhexis(Pearson's r=0.437,P=0.004).The regressive equation was:y=0.424x-6.326.According to the regressive equation,the diameter of capsulorhexis should be within 5.8mm to control the toric IOL rotation within 5.0°.Conclusions:Toric IOL has great rotational stability.The area of capsulorhexis has positively correlation with rotational stability,while there is no significant relevance between preoperative ACD,horizontal STS,LT,AL,target toric IOL axis and its rotation.A capsulorhexis within 5.8mm has an important significance on improving rotational stability.