Measurement of The Inner Macular Layers for Monitoring of Glaucoma: Confounding Effects of Age-Related Macular Degeneration.

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Abstract

To investigate the confounding effect of non-exudative age-related macular degeneration (AMD), specifically drusen and outer retinal atrophy, on the architecture and automated segmentation of the inner retinal layers as measured with optical coherence tomography (OCT).Observational cross-sectional study.265 consecutive eyes with non-exudative AMD were identified through retrospective chart review. Exclusion criteria were a diagnosis of glaucoma or glaucoma suspect, other retinal pathology affecting the macula, axial length >26.5mm or spherical equivalent less than -6D, any other optic nerve or neurological disorders, or poor image quality.Drusen were automatically segmented on macular OCT B-scans with a publicly available and validated deep learning approach. Automated segmentation of the inner plexiform layer (IPL)/inner nuclear layer (INL) boundary was carried out with the device’s proprietary software.Quality of segmentation of the IPL/INL boundary as a function of drusen size and presence of inner retinal layer displacement in the area of macular pathology (drusen or atrophy).125 eyes (65 patients) met the inclusion criteria. Drusen size varied between 16 and 272μm (mean 118μm). Automated segmentation had a 22% chance of failure if the drusen height was between 145 and 185μm and was most likely to fail with drusen heights above 185μm. When drusen height was normalized by the total retinal thickness, segmentation failed 36% of the time when the drusen to total retinal thickness ratio was 0.45 or above. Images were likely to show displacement of inner retinal layers with drusen heights above 176μm and a normalized drusen height ratio of 0.5 or higher. Eighty-seven percent of images with outer retinal atrophy displayed incorrect segmentation.Outer retinal diseases can alter retinal topography and affect segmentation accuracy of the inner retinal layers. Large drusen may cause segmentation error and compression of the inner macular layers. Geographic atrophy confounds automated segmentation in a high proportion of eyes. Clinicians should be cognizant of the effects of outer retinal disease on the inner retinal layer measurements when interpreting the results of macular OCT imaging in glaucoma patients.Copyright © 2022. Published by Elsevier Inc.