Abstract
Purpose :
This work aims to quantify the growth and the characteristics of atrophy in age-related macular degeneration (AMD) using spectral domain optical coherence tomography (SD-OCT).
Methods :
A 5-year prospective study of patients enrolled in a longitudinal study of dark adaptation (NCT01352975) with a range of AMD severities included annual imaging with SD-OCT (Spectralis, Heidelberg, Germany). Atrophy on SD-OCT was defined according to the Classification of Atrophy Meetings (CAM) guidelines as complete retinal pigment epithelium (RPE) and outer retinal atrophy (cRORA). SD-OCT volumes (30ox25o, 60 µm spacing) were first manually graded for presence/absence of cRORA and then a custom semi-automated algorithm contoured the cRORA regions in each OCT B-Scan. Enface 2D projection of the contoured cRORA regions was used to calculate the area atrophy (mm2). The growth rate of atrophy was calculated for each eye by finding the slope of the best linear fit of the square root area measurements over available timepoints.
Results :
Of the 31 patients with cRORA in either eye, 18 (58.1%) had unilateral cRORA whereas 13 (41.9%) had bilateral cRORA (i.e., total of 44 eyes with cRORA). Of these 44 eyes, 24 (54.0%) had cRORA already present at baseline (Group 1, median visual acuity 20/40), and 20 (45.5%) developed cRORA at follow-up visits (Group 2, median visual acuity 20/25). The mean (±SD) area of cRORA at the baseline visit for Group 1 was 2.88 ± 4.10 mm2 and at the first visit with cRORA in Group 2 was 0.66 ± 0.70 mm2. The median growth rate of atrophy in Group 1 (mean followup time 2.9 years) was 0.21 mm/year (range 0.024 - 0.64 mm/yr) and in Group 2 (mean followup time 1.3 years) was 0.17 mm/year (range -0.06 - 0.89 mm/yr). For eyes in Group 1, most visits (62.5%) had AMD severity scores 9 (non-central GA) or 10 (centrally involved GA) on color grading (range 5-10), while eyes in Group 2 had fewer visits (30%) with AMD severity scores of 9 or 10 (range 7-10).
Conclusions :
Assessment of cRORA/atrophy in OCT can augment the current understanding of atrophy and its growth using color or autofluorescence imaging modalities. The detection and quantification of small, incident areas of atrophy could be used as a more sensitive outcome of advanced disease. The accurate quantification of the growth of these lesions is important in understanding disease progression and for the design of clinical trials.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.