Purpose <p>Epiretinal proliferation (EP) is associated with poor visual and anatomical outcomes in eyes with macular holes (MHs). A preoperative cross-sectional OCT can detect EP; however, We observed that some cases with intraoperatively visible EP showed no evidence of EP on preoperative OCT. This study assessed the discrepancy between EP observed by OCT and during surgery.</p> Methods <p>We defined OCT-EP as epiretinal materials with homogeneous medium reflectivity observed in cross-sectional OCT. We defined surgical-EP as yellowish tissues contiguous to the hole during the membrane peeling. We detected the surgical-EP by also assessing the internal limiting membrane staining pattern using Brilliant Blue G (BBG) and preretinal abnormal tissue (PAT) using en face OCT.</p> Results <p>We included 110 eyes. Intraoperative observations revealed surgical-EP in 30 (27%) eyes, while preoperative OCT revealed EP in 26 (24%) eyes. Setting the surgical-EP as the ground truth gave a sensitivity of preoperative OCT for the detection of EP of 87% and specificity of 100%. In 4 of the 30 eyes (13%), EP was not detected on preoperative OCT and all of these eyes exhibited peri-MH nonstaining areas. Peri-MH nonstaining area and peri-MH PAT were larger in eyes with surgical-EP than in eyes without surgical-EP (P = 0.0001 and P = 0.0029).The area under the receiver operating characteristic curve was 84.3% for the peri-MH nonstaining area for detection of surgical-EP and 94.8% for peri-MH PAT.</p> Conclusions <p>Preoperative cross-sectional&#xa0;OCT may overlook EP. The BBG staining patterns and en face OCT provide additional clues for detecting EP.<Table Float="No" ID="Taba"> <Caption Language="En" xml:lang="en"> <CaptionContent> <p>Key messages</p> </CaptionContent> </Caption> <tgroup cols="1"> <colspec align="left" colname="c1" colnum="1" /> <tbody> <row> <entry align="left" colname="c1"> <p><Emphasis Type="BoldItalic">What is known</Emphasis></p> </entry> </row> <row> <entry align="left" colname="c1"> <p>• Epiretinal proliferation (EP) is a known biomarker correlated with poor visual and anatomical outcomes in eyes with macular hole.</p> </entry> </row> <row> <entry align="left" colname="c1"> <p>• Cross-sectional OCT is the standard modality for the detection of preoperative EP but may fail to identify subtle cases.</p> </entry> </row> <row> <entry align="left" colname="c1"> <p><Emphasis Type="BoldItalic">What is new</Emphasis></p> </entry> </row> <row> <entry align="left" colname="c1"> <p>• There is a 13% discrepancy between preoperative OCT and intraoperative observation to detect EP.</p> </entry> </row> <row> <entry align="left" colname="c1"> <p>• Using only preoperative cross-sectional OCT may overlook the presence of EP.</p> </entry> </row> <row> <entry align="left" colname="c1"> <p>• Brilliant blue G staining pattern and en face OCT may be useful to identify undetectable EP by OCT.</p> </entry> </row> </tbody> </tgroup> </Table></p>