Near-Infrared Reflectance Imaging for Quantification of Atrophy associated with Age-related Macular Degeneration

Abstract Purpose To compare measurements of area of geographic atrophy (GA) in dry age-related macular degeneration (AMD) obtained by fundus autofluorescence (FAF) to those obtained by near infrared reflectance (NIR). Design Inter-rater reliability analysis. Methods Ninety-seven confocal NIR images (Heidelberg HRA + Spectralis) and FAF images from 97 patients/eyes with GA with dry AMD were collected retrospectively from existing anonymized Doheny Image Reading Center datasets. Two masked reading center graders (NS and JS) independently and blindly performed manual segmentation of the GA lesions on each NIR and FAF image using GNU Image Manipulation Program (GIMP, ver 2.8.22) software. GA on NIR/FAF images was defined in accordance to recently published Classification of Atrophy Meeting criteria as sharply-demarcated hyper-reflective regions of at least 250 microns in diameter. The difference and point-to-point correspondence between gradings in GA area measurements between NIR and FAF were assessed by mean difference, overlap ratio and Dice similarity coefficient. Results Among the 97 eyes with dry AMD, mean GA area was 7.62 ± 7.77 mm2 from FAF images and 7.65 ± 7.83 mm2 from NIR, with a mean nonsignificant difference of 0.31 ± 0.55 mm2 (two-tailed t-test, p = 0.65). The overlap ratio in the segmented GA lesion between modalities was 0.84 ± 0.28 with a Dice similarity coefficient of 0.87 ± 0.27. Intermodal reliability was high (intra-class correlation coefficient/ICC = 0.998, p Conclusions GA lesions in dry AMD can be identified and quantified reliably using NIR images in many cases, though eyes with a thin choroid resulting in iso-reflective GA lesions may be challenging. As NIR imaging is comfortable for patients and is commonly obtained along with OCT, NIR-based GA assessment may be a useful surrogate in clinical settings.