A white membrane beneath the inner limiting membrane of the retina in a 4-year-old child with ultrastructural evidence: a case report

BACKGROUND Epiretinal membranes (ERMs), secondary to retinal cell proliferation on the retinal surface, usually affect patients over 50 years of age but occur rarely in children. Here we report the case of a 4-year-old patient with a unilateral sub-inner limiting membrane (sub-ILM) membrane mimicking epiretinal membrane with notable ultrastructural features indicating its possible origin from old sub-ILM hemorrhage. CASE PRESENTATION A 4-year-old boy was admitted with the complaint of poor vision in his right eye, which had been detected at school vision screening performed 6 months earlier. Fundal examination showed a feather-shaped white membrane in the macula of the right eye, and optical coherence tomography (OCT) revealed a thickened retina with a hyper-reflective band on the retinal nerve fiber layer. We suspected epiretinal membrane in the right eye, and pars plana vitrectomy with membrane peeling was performed to improve the patient's vision. Surprisingly, the membrane was found intraoperatively to be located beneath the intact ILM; it was lifted carefully from the underlying retina as it was strongly adhered to a retinal artery of the superotemporal arcade. Postoperative scanning electron microscopy showed that the membrane consisted of hemosiderin, collagenous fibre and fibrinoid deposits. At follow-up visits, fundal examination and OCT revealed improvement in the retinal structure with disappearance of the hyper-reflective band and reduced retinal thickness. The patient's visual acuity in the right eye was stable at 20/100 at 1 year post operation. CONCLUSIONS The white membrane presented here was found to lie between the intact ILM and the rest of the retina, adhering firmly to the superotemporal vessel arch. Given the ultrastructural findings of the membrane and the medical history, we speculate that the sub-ILM membrane probably developed secondary to a sub-ILM hemorrhage.