To observe the characteristics and prognosis of different types of intraretinal cystoid spaces in idiopathic epiretinal membranes (iERMs).
Two hundred and seven consecutive patients with symptomatic iERM who underwent vitrectomy between September 2016 and December 2019 were included. According to spectral-domain optical coherence tomography images, intraretinal cystoid spaces were classified into cystoid macular edema (CME) and microcystic macular edema (MME). Other optical coherence tomography characteristics, including ectopic inner foveal layers, central foveal thickness, and interdigitation zone integrity, were also evaluated.
Intraretinal cystoid spaces were presented in 30.1% of the iERMs, 21.5% were CME-type, 66.2% were MME-type, and 12.3% were combined-type. Compared with CME, eyes with MME-type and combined-type showed a significantly lower best-corrected visual acuity (BCVA) preoperatively and postoperatively. Cystoid macular edema is always presented in earlier stages (92.9%) and has no significant effects on BCVA (PStage I = 0.927, PStage II = 0.985). Conversely, MME is the primary type in advanced stages associated with a longer duration of symptoms (P = 0.037) and lower preoperative BCVA (P = 0.008). After surgery, cystoid spaces were newly occurred in 33 eyes (21.6%), with no effects on BCVA (P = 0.668). In the multiple regression analysis, the presence of MME was a risk factor for preoperative BCVA (P = 0.001). However, it is not an independent predictor for the postoperative VA.
Our research further proved that MME is an adverse factor for preoperative and postoperative VA in iERMs. Moreover, we underlined the importance of distinguishing between CME and MME, which may affect prognosis differently.