Immunohistochemical clinicopathologic correlation and OCT analysis of idiopathic and secondary epiretinal membrane specimens

To investigate correlation of clinical, optical coherence tomography (OCT), and immunohistochemistry (IHC) in idiopathic and secondary epiretinal membrane (ERM).

Retrospective review of patients undergoing pars plana vitrectomy with membrane peeling (PPV-MP). Excised membranes were evaluated by IHC staining for glial fibrillary acidic protein (GFAP), α-smooth muscle actin (α-SMA), cytokeratin, pigment, and fibrosis grading. Pre-operative and post-operative OCTs, and clinical follow-up information at least 3mo were collected.

This study analyzed 104 eyes of 104 patients, of whom 83 (79.8%) had idiopathic ERM (iERM) and 21 (20.2%) had secondary ERM (sERM). Mean age at the time of surgery was 67.3±10.5y. OCT demonstrated greater foveal distortion (P=0.012), intraretinal (IR) spaces (P=0.009), and ellipsoid zone (EZ) discontinuity (P=0.022) in sERMs. Poorer pre-operative BCVA for all cases correlated with foveal distortion (P=0.011), loss of parallelism (P=0.014), IR spaces (P=0.027), and EZ disruption (P=0.012). Poorer post-operative BCVA for all cases was associated with foveal distortion (P=0.027). GFAP was expressed in nearly all ERMs (99%). Pigment was expressed more in sERM (61.9%) compared with iERM (21.7%; P=0.005) and associated with poorer post-operative BCVA (P=0.035) and ERM dehiscence (P=0.008). Fibrosis severity correlated with poorer pre-operative BCVA (P=0.027). GFAP intensity correlated with longer symptom duration (P=0.002).

The high prevalence of many cell types not distinguished for iERM versus sERM suggests a common pathway of formation with local influences rather than an etiologic cell type or substrate location.