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

Written by: Edward H. Wood, MD

September 2021

Lee Dong Hyun, Sung Eun Park, and Christopher Seungkyu Lee. 2020. “Microcystic Macular Edema and Cystoid Macular Edema Before and After Epiretinal Membrane Surgery.” Retina Publish Ahead of Print (December). https://doi.org/10.1097/IAE.0000000000003087.

This study is clinically useful by expanding our understanding of 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 which underwent vitreoretinal surgery for idiopathic ERM with associated pre-operative fluorescein angiography (FA) and optical coherence tomography (OCT). The exclusion criteria ensured the evaluation of principally idiopathic ERMs.

Pre-operative intraretinal cystoid spaces on OCT were present in 54 (54%) of patients with ERM. The authors then subdivided intraretinal cystoid spaces based on FA findings into two groups: cystoid spaces with FA leakage termed cystoid macular edema (CME), and cystoid spaces 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 Muller cell dysfunction.

Following vitreoretinal surgery with ERM peeling and additional ILM peeling (84%), the authors found that eyes displaying pre-operative CME experienced a significant reduction in CME (p<0.001), whereas eyes with pre-operative MME did not experience a reduction in MME (p=0.302). The authors identified numerous biomarkers associated with favorable visual outcomes following surgery including the absence of preoperative MME (p=0.035), poorer initial visual acuity (p=0.033), increased central foveal thickness (p=0.018), and intact ellipsoidal zone (p=0.035).

In addition to other known biomarkers, the authors concluded that the presence of intraretinal cystoid spaces 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.