Assessment of Proliferative Vitreoretinopathy in Rhegmatogenous Retinal Detachment with OCT: Revisiting the 1991 Retina Society Classification.

Purpose: To characterize proliferative vitreoretinopathy(PVR) with swept-source optical coherence tomography(SS-OCT) in rhegmatogenous retinal detachment(RRD).

Design: Prospective cross-sectional cohort study.

Subjects: Consecutive primary RRDs presenting to St. Michael's Hospital from 2021 to 2023.

Methods: Ultra-widefield(UWF) fundus imaging was staged per the Retina Society 1991 PVR Classification and correlated with retinal microstructural changes assessed with SS-OCT.

Main outcome measures: SS-OCT findings in PVR.

Results: 100 patients were included. Patients with no signs of PVR or PVR A (49/100) were more likely to have a preserved bacillary layer on SS-OCT with low-amplitude outer retinal corrugations(ORCs) compared to the PVR B/C group. PVR B(retinal wrinkling/vessel tortuosity) was present in 24%(24/100) of cases, all of which had high-amplitude ORCs. PVR C (27/100) was clinically divided into patients with subretinal membranes(SR) [63%(17/27)] and patients with fixed retinal folds(IR)[37%(10/27)]. The SR subtype was associated with shallow, slowly progressive detachments. On SS-OCT, they had a thick hyperreflective membrane emanating from the retinal pigment epithelium and extending along the outer retinal surface, causing tractional folds of the outer retina in 47%(8/17) of cases and tractional bacillary layer detachment in 12%(2/17) of cases. Outer retinal thinning/atrophy was commonly observed in the SR subtype. Patients with the IR subtype had bullous detachments on fundus examination and extensive intra-retinal changes on SS-OCT. These had a thickened bacillary layer with high-amplitude ORCs with photoreceptor-photoceptor apposition within or between individual corrugations(fused ORCs). Significant pre-retinal membranes with loss of differentiation of the inner and outer retinal lamellae and distortion of underlying ORCs were observed.

Conclusion: Our study demonstrates imaging evidence of varying PVR morphology. The IR subtype occurs in bullous detachments with intrinsic retinal changes that span from fused and distorted corrugations to retinal thickening, pre-retinal membranes and loss of differentiation of retinal lamella. The SR subtype occurs in shallow, slowly progressive detachments, where the proliferation is associated with membranes emanating from the RPE, outer retinal thinning/atrophy and tractional outer retinal folds. We present a novel OCT classification of primary PVR, which varies based on RRD morphology. Pathological intraretinal apposition in ORCs may contribute to glial proliferation and subsequent intra-retinal and pre-retinal changes.