Microvascular Properties of Dissociated Optic Nerve Fiber Layer (DONFL) After Internal Limiting Membrane Peeling.

Purpose: To investigate the microvascular properties of dissociated optic nerve fiber layer (DONFL) after internal limiting membrane (ILM)-peeling in the treatment of epiretinal membrane (ERM) using optical coherence tomography angiography (OCTA). Methods: A prospective, bicentric study of 52 eyes undergoing pars plana vitrectomy (PPV) with ERM- and ILM-peeling for symptomatic ERM. Patients were visited before surgery (baseline), as well as four weeks (V1) and 12 weeks (V2) after surgery. A peer-review-approach of four independent graders and a semi-automated computer-assisted algorithm were conducted to define areas as DONFL, peri-DONFL and non-DONFL. In all areas, perfusion density, vessel density and vessel distance of the superficial and deep capillary plexus were assessed using OCTA. Results: Of the 52 eyes, a total of 48 eyes reached postoperative visits and were included in further analyses. The incidence of DONFL was 39.58% at V1 and 52.08% at V2. Both in the superficial and the deep vascular plexus, perfusion density and vessel density of DONFL areas were lower than in peri-DONFL and non-DONFL areas, while vessel distance was higher (P < 0.05). Moreover, in the deep capillary plexus vessel density at V1 and V2 and perfusion density at V1 were higher and vessel distance at V1 was lower in peri-DONFL than in non-DONFL areas (P < 0.05). Conclusions: DONFL is accompanied by a shift within the microvascular network, with capillaries presumably being displaced from DONFL into peri-DONFL areas. These findings support the thesis of a more extensive reorganization of retinal structures that goes markedly beyond the retinal nerve fibre layer.