Outer Retinal Corrugations in Rhegmatogenous Retinal Detachment: The Retinal Pigment Epithelium-Photoreceptor Dysregulation Theory.

PURPOSE: Outer retinal folds occur when outer retinal corrugations (ORCs) persist after retinal reattachment with worse functional outcomes. We investigate the pathophysiology of ORCs in vivo. DESIGN: Prospective cohort study. METHODS: Patients with rhegmatogenous retinal detachment (RRD) presenting to St. Michael's Hospital, Toronto, Ontario, Canada, between August 2020 and February 2022 were assessed with swept-source optical coherence tomography (SS-OCT) and ultra-widefield SS-OCT for ORCs. Clinical characteristics of eyes with/without ORCs were compared. Mathematical models were used to deduce mechanical properties leading to ORCs. RESULTS: Sixty-six patients were included. More than half (60.6%, 40/66) were fovea-off and 48.4% (32/66) had ORCs at presentation. All eyes (32/32) with ORCs had retinal pigment epithelium (RPE)-photoreceptor dysregulation for at least 2 days, defined as loss of RPE control with acute, progressive, and extensive RRDs. In all (34/34) eyes without ORCs the RPE was in relative control of the subretinal space with nonprogressive subclinical or small localized or resolving RRDs, or with RPE-photoreceptor dysregulation for fewer than 2 days. Mathematical models indicate that a modulus of elasticity of the outer retina relative to the inner retina of 0.05 to 0.5 leads to ORCs. CONCLUSIONS: ORCs develop with (1) acute exposure of subretinal space to liquified vitreous, (2) for >2 days, that (3) overwhelms RPE capacity, leading to progressive and extensive RRD. Mathematical models suggest that a reduction in the modulus of elasticity of the outer retina occurs such that intrinsic compressive forces, likely related to progressive outer retinal hydration and lateral expansion, lead to ORCs. Understanding the pathophysiology of ORCs has implications for management.