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

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).

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.

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).

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.