Correlation of inner-retinal irregularity index with visual function before and after surgery in idiopathic macular epiretinal membrane

Miao ZENG; Xiao CHEN; Ling HONG; Chunyan CAI; Qin DING

ABSTRACT

Objective:

To observe the changes of the inner-retinal irregularity index (IRII) of eyes with idiopathic macular epiretinal membrane (IMEM) before and after surgery and its correlation with visual function.

Methods:

retrospective series of studies. From March 2017 to May 2018, 46 IMEM patients (46 eyes) diagnosed in the Department of Ophthalmology of Central Theater Command General Hospital were included in the study. BCVA, visual deformation degree (M), OCT inspection with swept source were all performed. The BCVA examination was carried out using the international standard visual acuity chart, which was converted into logMAR visual acuity for record. The average IRII was 1.255±0.048, the average logMAR BCVA was 0.63±0.21, the average M value was 0.68±0.38, the average of central macular thickness (CMT) was 353.57±73.92 μm, the average inner retinal layer thickness (IRT) was 181.50±40.91 μm. The complete and incomplete ellipsoid zone (EZ) were 17 and 29 eyes, respectively. All eyes underwent a 25G three-incision closed vitrectomy through the flat part of the ciliary body, and the epiretinal membrane and inner limiting membrane were removed at the same time. The changes of IRII, M value, BCVA, CMT, IRT and EZ were observed at 1, 3, 6, and 12 months after surgery, and the correlation were analyzed between IRII and M value and BCVA before and after surgery. Single-factor repeated measurement data analysis of variance was used for the comparison of BCVA, M value, CMT, and IRT before and after surgery. Spearman rank correlation analysis were adopted for the correlation analysis between IRII and BCVA, M value, CMT, IRT and EZ integrity before and after surgery.

Results:

Twelve months after surgery, the average IRII and logMAR BCVA were 1.175±0.032 and 0.47±0.16, respectively. Compared with those before surgery, they were significantly improved, and the difference was statistically significant ( F=22.273, 5.453; P<0.001, <0.001). The average M value ( F=20.109), CMT ( F=14.273), IRN ( F=13.665) were significantly lower than those before the operation, and the difference was statistically significant ( P<0.001, 0.001, <0.001). The integrity of EZ was significantly improved compared with that before surgery, and the difference was statistically significant ( χ 2=12.715, P<0.001). The results of correlation analysis showed that preoperative IRII was positively correlated with preoperative M value and CMT ( r=0.951, 0.701; P<0.001, <0.001). It was positively correlated with postoperative M value, logMAR BCVA, CMT and EZ integrity ( r=0.650, 0.369, 0.720, 0.293; P<0.001,<0.001, P=0.048). It was not correlated with preoperative logMAR BCVA and EZ integrity ( r=0.283, 0.001; P=0.056, 0.996).

Conclusion:

The IRII of IMEM eyes before surgery is significantly correlated with the BCVA and M values after surgery.