Incomplete Retinal Pigment Epithelial and Outer Retinal Atrophy (iRORA) in Age-related Macular Degeneration: CAM Report 4

Abstract Purpose To describe the defining features of “incomplete retinal pigment epithelial (RPE) and outer retinal atrophy” (iRORA), a consensus term referring to the optical coherence tomography (OCT) based anatomical changes often identified prior to the development of “complete RPE and outer retinal atrophy (cRORA)” in age-related macular degeneration (AMD). We provide descriptive OCT and histological examples of disease progression. Design Consensus meeting Participants Panel of retina specialists, including retinal imaging experts, reading center leaders and retinal histologists. Methods As part of the Classification of Atrophy Meeting (CAM) program, an international group of experts analysed and discussed longitudinal multimodal imaging of eyes with AMD. Consensus was reached on a classification system for OCT-based structural alterations that occurred prior to the development of atrophy secondary to AMD. New terms of complete and incomplete RPE and outer retinal atrophy (iRORA and cRORA) were defined. This report describes in detail the CAM consensus on iRORA. Main Outcome Measures Defining the term iRORA through OCT imaging and longitudinal cases showing progression of atrophy, with histologic correlates. Results OCT was used in cases of early and intermediate AMD as the base imaging modality to identify cases of iRORA. In the context of drusen, iRORA is defined on OCT as (1) a region of signal hypertransmission into the choroid and (2) a corresponding zone of attenuation or disruption of the RPE, and (3) evidence of overlying photoreceptor degeneration. The term iRORA should not be used when there is an RPE tear. Longitudinal studies confirmed the concept of progression from iRORA to cRORA. Conclusions An international consensus classification for OCT-defined anatomical features of iRORA, are described and examples of longitudinal progression to cRORA are provided. The ability to identify these OCT changes reproducibly, is essential to better understand the natural history of disease, to identify high risk signs of progression and to study early interventions. Longitudinal data are required to quantify the implied risk of vision loss associated with these terms. The CAM classification provides initial definitions to enable these future endeavours, acknowledging that the classification will be refined as new data are generated.