Quantitative analysis of longitudinal changes in multimodal imaging of Late-Onset Retinal Degeneration

Purpose To quantitatively analyze clinically relevant features on longitudinal multimodal imaging of L-ORD (late-onset retinal degeneration) to characterize disease progression. Methods Fundus autofluorescence (FAF), infrared reflectance (IR), and optical coherence tomography (OCT) imaging of 4 L-ORD patients were acquired over 3-15 years (20 visits total). Corresponding regions-of-interest were analyzed on FAF (reticular pseudodrusen (RPD), "speckled FAF", and chorioretinal atrophy) and IR (hyporeflective RPD and target RPD) using quantitative measurements including contour area, distance to fovea, contour overlap, retinal thickness, and texture features. Results Cross-sectional analysis revealed moderate correlation (RPD FAF ∩ RPD IR = 63%) between contour area across modalities. Quantification of retina thickness and texture analysis of areas contoured on FAF objectively differentiated the contour types. Longitudinal analysis of aligned images demonstrates that the contoured region of atrophy both encroaches toward the fovea and grows monotonically with a rate of 0.531-1.969 mm/year (square root of area, n=5 eyes). A retrospective analysis of precursor lesions of atrophy reveals quantifiable progression from RPD to speckled FAF to atrophy. Conclusions Image analysis of timepoints prior to the development of atrophy reveals consistent patterns over time and space in L-ORD that may provide useful outcomes for L-ORD and other degenerative retinal diseases.