Meniscus Micropyon: An Ophthalmoscopic Sign Possibly Associated with Epiretinal Proliferation After Retinal Surgery with Gas Tamponade

To describe an ophthalmoscopic sign, termed a meniscus micropyon, and its possible association with proliferative vitreoretinopathy (PVR)/epiretinal membrane (ERM) formation after retinal surgery with gas tamponade. Patients with intravitreal gas were examined postoperatively by 1 of 6 vitreoretinal surgeons from 4 institutions. A micropyon was defined as a white-yellow, solid-appearing consolidation along the meniscus (i.e., the fluid-gas interface). A micropyon was visualized and photographed in 49 patients who received intravitreal gas. Preoperatively, retinal breaks were present in all 49 eyes and rhegmatogenous retinal detachment (RRD) in 45 (92%). Postoperatively, 39 eyes (80%) developed epiretinal proliferation: 16 eyes (33%) developed recurrent RRD from PVR, 6 eyes (12%) re-detached without frank PVR, 9 eyes (18%) developed postoperative ERM/worsening and 8 eyes (16%) had postoperative ERM but no preoperative OCT to determine if the postoperative ERM was new or worsening. The single-operation anatomic success in eyes with a micropyon was 51%, which was lower than that of a contemporaneous RRD control group (91%) in which no micropyon was detected. In 2 patients, micropyons were biopsied during PPV and examined histopathologically; they consist predominantly of white blood cells (WBCs). The meniscus micropyon is an ophthalmoscopic sign that can occur after retinal surgery with gas tamponade. Features that distinguish a micropyon from post-vitrectomy fibrin/fibrinoid syndrome include delayed appearance, hyperautofluorescence, absence of translucent strands or sheets in the anterior chamber or vitreous cavity, and the histopathologic identification of WBCs. A clinically detectable micropyon may be a biomarker of PVR/ERM formation.