## 3 Results  
For this study 151 patient records were reviewed. According to inclusion and exclusion criteria, 84 patients were excluded. Therefore, 67 subjects were considered in the statistical analysis. The cohort consisted of 23 (34%) females and 44 (66%) males. The mean age was 67 (61-87) years. The mean follow-up time was 20 months (3-70). Most surgeries were performed without phacoemulsification and implantation of a posterior chamber intraocular lens (n = 45; 67%). Prior to surgery, all patients presented with ERM (Figure 2). The stages of ERM were homogenously distributed. At baseline, most patients did not show alterations of the CB (n = 45; 66%). CB alterations were detected in 22 eyes (34%) prior to surgery, with stage 1 alterations being the most common (Table 1, Figure 1). Mean BCVA before was 0.42 (\(\pm\)0.26) LogMAR before surgery and 0.20 (\(\pm\)0.22) LogMAR after surgery (\(p\) < 0.001). A mean improvement of 0.22 LogMAR units was reached, indicating a significant mean gain in vision of almost 2.5 lines (Table 2). The mean CB stage at baseline was 0.55 (\(\pm\)0.93) and improved to 0.27 (\(\pm\)0.59) following surgery (\(p\) = 0.002). Of all the patients with foveal changes at baseline (n = 22, 34%), a significant amount (n = 15, 68%) had lower grading of CB alteration after the surgery than before (\(p\) = 0.002). Only three (4.5%) eyes showed any increase in CB alteration stage. For the five eyes (7.5%) showing the most severe form of CB abnormality (Stage 3), four eyes (80%) showed improvements in their respective stages and one stayed the same. Most eyes with stage 1 originally showed no signs of CB alteration after surgery was performed (n = 6, 50%). All eyes showed an improvement in ERM grading, with 98.5% reaching stage 0 (n = 66 vs. n = 67; \(p\) < 0.001). Remaining ERM fragments were detected in the OCT follow-up exam after surgery in only one patient. In this case, the ERM stage improved from stage 4 to stage 1 after surgery. At baseline, the mean ERM stage was 2.45 (\(\pm\)1.12), and it improved to 0.01 (\(\pm\)0.12) after surgery (\(p\) < 0.001). No significant difference in BCVA changes was observed when comparing surgeries including cataract removal to those without (\(-\)0.16 vs. \(-\)0.25 LogMAR, \(p\) = 0.196). No significant difference in BCVA improvement following surgery was found amongst different stages of ERM (\(p\) = 0.528) and CB alterations (\(p\) = 0.841) at baseline (Table 3). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Cohort Criteria** & **N (\%/Range)** & **Mean BCVA** \\
**(N = 67)** & **N (\%/Range)** & **(LogMAR)** \\ \hline Gender & & \\ Female & 23 (34) & 0.419 \\ Male & 44 (66) & 0.412 \\ Age (years) & 67 (61–87) & \\ ERM & & \\ Stage 1 & 19 (28) & 0.392 \\ Stage 2 & 13 (20) & 0.408 \\ Stage 3 & 21 (31) & 0.392 \\ Stage 4 & 14 (21) & 0.486 \\ CB alteration stages & & \\ Stage 0 & 45 (66) & 0.468 \\ Stage 1 & 12 (18) & 0.310 \\ Stage 2 & 5 (8) & 0.280 \\ Stage 3 & 5 (8) & 0.320 \\ Surgery & & \\ With phaco & 22 (33) & 0.365 \\ Without phaco & 45 (67) & 0.439 \\ Follow-up time (months) & 20 (3–70) & \\ \hline ERM = epiretinal membrane; CB = central foveal bouquet; phaco = phacoumulsification and implantation of posterior chamber intraocular lens. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Baseline characteristics of study cohort. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \begin{tabular}{c} **Before Surgery** \\ **(Mean; \(\pm\)SD)** \\ \end{tabular} & \
\begin{tabular}{c} **After Surgery (Mean;** \\ \(\pm\)SD)** \\ \end{tabular} &
\begin{tabular}{c} **\(p\)-Value * \\ \end{tabular} \\ \hline BCVA & 0.42 \(\pm\) 0.26 & 0.20 \(\pm\) 0.22 & \textless{}0.001 \\ CB stage & 0.55 \(\pm\) 0.93 & 0.27 \(\pm\) 0.59 & 0.002 \\ ERM stage & 2.45 \(\pm\) 1.12 & 0.01 \(\pm\) 0.12 & \textless{}0.001 \\ \hline \hline \end{tabular}  
* Paired samples test (T-Test).  
\end{table} 
Table 2: Influences of surgery on different parameters.