RESUMO
Objective To investigate the changes of metamorphopsia between before and after surgery in the patients with idiopathic epiretinal membrane and its influence factors.Methods A series cases observitional study included 39 eyes of 39 patients with idiopathic epiretinal membrane.Follow-up was carried out at 1 week before surgery and 3,6 months after surgery respectively.M-chart was used to quantify the severity of metamorphopsia (M-score).EDTRS visual chart was used to quantify best corrected visual acuity (BCVA) (converted to LogMAR).Central subfield thickness (CST),central foveal volumn (CV),cube average thickness (CAT),central foveal thichness (CFT),ganglion cell layer (GCL) thickness,inner nuclear layer (INL) thickness,outer nuclear layer (ONL) and outer plexiform layer (OPL) thickness,the integrity of external limiting membrane,ellipsoid zone and interdigitation zone were analyzed by using spectral domain-optical coherence tomography (OCT).This study protocol was approved by Ethic Committee of Beijing Tongren Hospital (No.TRECKY-012).Written informed consent was obtained from each subject before surgery.Results Mean M-score was significantly decreased from 0.8 (0.3,1.1) before surgery to 0.5 (0.2,0.8) at 3 months after surgery,with a significant difference between the two time points (Z=-2.013,P=0.044).Mean M-score was 0.6(0.2,0.8) at 6 months after surgery,which was not significantly different in comparison with before surgery and 3 months after surgery (Z =-1.873,P =0.061;Z =-0.288,P =0.773).Compared with before surgery,the horizontal M-score was significantly decreased 3 months and 6 months after surgery (Z =-2.329,P =0.020;Z =-2.858,P =0.004).No significant difference was found in vertical M-score among before surgery and 3,6 months after surgery (all at P＞0.05).The BCVA was improved from 0.40 (0.30,0.66) before surgery to 0.20 (0.06,0.42) 3 months after surgery and declined to 0.30 (0.10,0.52) at 6 months after surgery,and significant differences were obtained between 3 months after surgery and before surgery or 6 months after surgery (Z =-4.087,P＜0.001;Z =-2.235,P =0.025).Compared with before surgery,the BCVA in cataract combined with vitrectomy operative group was significantly improved in 3 months and 6 months after surgery (Z=-2.613,P=0.009;Z=-2.466,P=0.014) and the BCVA in only vitrectomy group was significantly improved at 3 months after surgery but decreased 6 months after surgery,showing significant differences between 3 months after surgery and before surgery or 6 months after surgery (Z =-3.104,P =0.002;Z =-3.464,P =0.001).Preoperative M-score was positively correlated with preoperative BCVA,preoperative CST or preoperative CFT (rs =0.384,P =0.016;rs =0.585,P＜0.001;rs =0.601,P＜0.001).No correlation was found between BCVA with GCL,INL or ONL + OPL thickness.Horizontal M-score was positively correlated with CST,postoperative CV and postoperative CAT (rs=0.322,P=0.045;rs=0.340,P=0.034;rs =0.336,P=0.036),and no correlation was found between horizontal M-score and BCVA,CFT,GCL thickness,INL thickness,ONL+OPL thickness in 6 months after surgery.The vertical M-score and mean M-score were not correlated with OCT parameters in 6 months after surgery.The mean M-score was positively correlated with preoperative mean M-score,preoperative CST,preoperative CV,preoperative CAT in 6 months after surgery (rs =0.589,P＜0.001;rs =0.330,P =0.040;rs =0.404,P =0.011;rs =0.410,P =0.009).In addition,and no significant correlation between mean M-score and preoperative BCVA,CFT,GCL thickness,INL thickness,ONL+OPL thickness.Multivariate stepwise linear regression showed that preoperative M-score was a predictor of postoperative M-values (adjusted R2 =0.211,P =0.002).Conclusions Most metamorphopsia can be alleviated after idiopathic epiretinal membrane surgery.The residue metamorphopsia after surgery probably is correlated with preoperative metamorphopsia and CFT.