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Oscar Otero-Marquez, Wei Wei, Marco Mazzola, K Bailey Freund, Theodore Smith; Quantitative Fundus Autofluorescence Defines Two Pathways to Geographic Atrophy secondary to Age-related Macular Degeneration.. Invest. Ophthalmol. Vis. Sci. 2020;61(9):PB0026.
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To measure the qAF signals in lobules of GA secondary to AMD, and to correlate qAF levels with the dominant intermediate AMD (iAMD) precursor lesion type (soft drusen/PED or SDD).
23 eyes of 18 patients with GA underwent spectral-domain optical coherence tomography (SD-OCT) and qAF imaging on the Heidelberg Spectralis. We examined prior serial tracked OCT scans of 52 GA Regions-of-interest (ROIs), lobules or coalescent atrophic lobules, for mean follow-up 5.5 years to divide them into 2 pathways by the dominant predecessor iAMD lesion type: soft drusen/pigment epithelial detachment (PED), pathway 1; subretinal drusenoid deposits (SDD), pathway 2. Some ROIs arose from both pathways, and were assigned to a mixed group. Mean qAF values of GA ROIs were measured and compared between the 3 groups.
The soft drusen/PED pathway (18/52) led to GA lesions that were “black” on AF, with lower mean qAF (35.88±12.75 qAF units), generally displaying the complete atrophy of the RPE and outer retina (cRORA) phenotype. The SDD pathway (12/52) led to GA lesions that were multilobular and “gray” on AF, with higher mean qAF (71.62±12.12 qAF units, P<0.001, t-test), generally displaying the incomplete atrophy of the RPE and outer retina (iRORA) phenotype. The mean qAF of ROIs from the mixed pathway (22/52) was intermediate (58.13±11.88 qAF units).
In most cases, GA lesions can be divided by qAF (lower/higher) into 2 non-exclusive groups that correlate with the precursor pathway (soft drusen/PED or SDD) and their predominant final OCT atrophy classification (cRORA or iRORA), with remaining lesions arising from both forms of iAMD, with intermediate qAF. Thus, qAF of GA lobules reflects both their pathogenesis and structure, and would be an easily implemented and useful metric for clinical GA research.
This is a 2020 Imaging in the Eye Conference abstract.
Example of pathway 1 to GA. Precursor lesion type soft drusen/PED. The mean qAF of the Region-of interest (ROI) within the green outline is 26.31 qAF units, with a GA area of 0.81mm2. SD-OCT illustrates the features of complete RPE and outer retinal atrophy (cRORA).
Example of pathway 2 to GA. Precursor lesion type SDD. The Mean qAF value within Region-of interest (ROI), within the green outline is 60.32 qAF units with a GA area of 2.22 mm2. SD-OCT shows incomplete RPE and outer retinal atrophy (iRORA).
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