Deep and superficial OCT angiography changes after macular peeling: idiopathic vs diabetic epiretinal membranes

To assess changes in deep and superficial perifoveal capillary plexus after macular peeling in idiopathic and diabetic epiretinal membrane (iERM and dERM, respectively).

Cross-sectional comparative study. We included 40 eyes from 40 patients affected by iERM (20 eyes) and dERM (20 eyes), as well as 34 eyes from 17 healthy, age-matched patients. Patients received a complete ophthalmic evaluation including axial and en-face scanning spectral-domain analysis, optical coherence tomography angiography, and microperimetry. Split-spectrum amplitude-decorrelation angiography images were obtained to quantify the deep and superficial layers of perifoveal capillary-free zone (CFZ). The main outcome measures were: (i) differences at baseline between deep and superficial CFZ in iERM and dERM vs control, and (ii) changes in deep and superficial CFZ plexus after surgery in iERM vs dERM.

The deep CFZ only significantly increased in dERM at the end of the follow-up period (6 months). No statistically significant differences were found between preoperative and postoperative superficial vascular plexus in iERM or dERM. At the end of the follow-up, statistically significant differences between preoperative and postoperative ganglion cell complex (GCC) average were found only in the iERM group. Best-corrected visual acuity significantly improved after surgery both in the iERM (P = 0.0053) and dERM (P < 0.0001) groups. After 6 months, macular sensitivity increased in the iERM group, but there was no statistically significant change in the dERM group.

In dERM, the deep CFZ significantly increases after ILM peeling, whereas postoperative angiography changes were not significant in iERM. This could be because the impaired diabetic perifoveal capillary plexus are more sensitive to the iatrogenic damage to Müller cells, induced by peeling.