Comparisons Among Optical Coherence Tomography and Fundus Autofluorescence Modalities as Measurements of Atrophy in ABCA4-Associated Disease

PURPOSE: In ABCA4-associated retinopathy, central atrophy was assessed by spectral domain optical coherence tomography (SD-OCT) and by short-wavelength (SW-AF) and near-infrared (NIR-AF) autofluorescence. METHODS: Patients exhibited a central atrophic lesion characterized by hypoautofluorescence (hypoAF) surrounded either by hyperautofluorescent (hyperAF) rings in both AF images (group 1, 4 patients); or a hyperAF ring in SW-AF but not in NIR-AF images (group 2, 11 patients); or hyperAF rings in neither AF images (group 3, 11 patients). Choroidal hypertransmission and widths of ellipsoid zone (EZ) loss were measured in foveal SD-OCT scans, and in AF images hypoAF and total hypo+hyperAF widths were measured along the same axis. Bland-Altman and repeated measures analysis of variance with Tukey post hoc were applied. RESULTS: For all groups, hypertransmission widths were significantly smaller than EZ loss widths. In Groups 1 and 2, hypertransmission width was not significantly different than SW-hypoAF width, but hypertransmission was narrower than the width of SW-hypo+hyperAF (groups 1, 2) and NIR-hypo+hyperAF (group 1). In group 3, the hypertransmission width was also significantly less than the width of SW-hypoAF and NIR-hypoAF. The EZ loss widths were not significantly different than measurements of total lesion size, the latter being the widths of SW-hypo+hyperAF and NIR-hypo+hyperAF (group 1); widths of NIR-hypoAF and SW-hypo+hyperAF (group 2); and widths of NIR-hypoAF and SW-hypoAF (group 3). CONCLUSIONS: Hypertransmission and SW-hypoAF (except when reflecting total lesion width) underestimate lesion size detected by EZ loss, SW-hypoAF+hyperAF, and NIR-hypo+hyperAF. TRANSLATIONAL RELEVANCE: The findings are significant to the selection of outcome measures in clinical studies.