Microcystic Macular Edema and Cystoid Macular Edema Before and After Epiretinal Membrane Surgery

This study is clinically useful by expanding imaging biomarkers of idiopathic epiretinal membranes (ERM) undergoing vitreoretinal surgery that can facilitate prognostication and patient education. 

This was a retrospective cross-sectional study that included 100 eyes who underwent vitreoretinal surgery for idiopathic ERM with associated preoperative fluorescein angiography (FA) and optical coherence tomography (OCT). The exclusion criteria ensured the evaluation of principally idiopathic ERMs.

Preoperative intraretinal cysts on OCT were present in 54 (54%) of patients with ERM. The authors then subdivided intraretinal cysts based on FA findings into two groups: cysts with FA leakage termed cystoid macular edema (CME) and cysts without FA leakage termed microcystic macular edema (MME). CME was present in 18% of eyes, MME was present in 27% of eyes, and both CME and MME were present in 9% of eyes. MME can be seen on OCT as well circumscribed areas of hypo-reflectivity predominantly in the inner nuclear layer and may indicate mueller cell dysfunction.

Following vitreoretinal surgery with ERM peeling and additional internal limiting membrane peeling (84%), the authors found that eyes displaying preoperative CME enjoyed a significant reduction in CME (P < .001) whereas eyes with preoperative MME did not experience a reduction in MME (P = .302). The authors identified numerous biomarkers associated with favorable visual outcomes following surgery, including the absence of preoperative MME (P = .035), poorer initial visual acuity (P = .033), increased central foveal thickness (P = .018), and intact ellipsoidal zone (P = .035).

In addition to other known biomarkers, the authors concluded that the presence of intraretinal cysts on OCT without FA leakage (MME) portend a poor prognosis in eyes undergoing surgery. MME may represent chronic structural changes less amenable to improvement. Future studies may evaluate which patients are likely to progress to MME and the possible benefit of surgery prior to the development of MME.