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Julia Margaret Agee, Meleha Ahmad, Akash Rastogi, Yuehong Tong, Ryan Larochelle, Christine Curcio, Theodore Smith; Fundus Autofluorescence Patterns within Geographic Atrophy (GA) in Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2017;58(8):34.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of our study is to describe patterns of fundus autofluorescence (FAF) within GA in eyes with reticular macular disease (RMD). The loss of retinal pigment epithelium (RPE) cells in GA makes the lesions so dark that patterns are difficult to discern, but it is clear that the hypoautofluorescence (hypoAF) is not uniform (PMID 27552292). On histopathology, it has been observed that the atrophic zone contains dissociated RPE and persistent basal laminar deposits (PMID 26024109). We sought to identify patterns of FAF heterogeneity in vivo, which might support ex vivo findings of cellular complexity in apparently empty areas of atrophy.
We analyzed FAF imaging of 11 eyes of 11 patients with GA and RMD. We segmented GA lesions and calculated histograms of the gray levels with Adobe Photoshop. We then divided the gray levels into quartiles with SPSS, after which we color-coded corresponding pixels by quartile to demonstrate variation with Adobe Photoshop.
Relative FAF gray level analysis of GA, color-coded by quartile on original imaging, demonstrated variability within lesions and between lesions. Varying levels of hyperautofluorescent (hyperAF) granularity were observed in all lesions. A hypoAF pattern was observed within the GA that resembled, in size and spacing, the pattern of hypoAF points in adjacent RMD regions. Six examples are shown (Fig).
FAF gray levels in GA are neither uniform nor randomly variable. These features become easier to observe when gray levels are color-coded by quartile. Stereotyped variability is demonstrated as interpretable patterns of hypo or hyperAF. The hyperAF granularity may represent residual islands of viable RPE as reported by Curcio et al. The size and spacing of the hypoAF pattern within the GA are similar in appearance to those in adjacent RMD. We speculate that these sites of hypoAF may compose a continuum of disease from RMD to GA, as structures of the outer retina are lost and AF decreases. Correlation with high-resolution OCT and histopathology is warranted to provide further insight into this complex AMD phenotype.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Quartile Analysis of FAF Gray Levels in 6 GA eyes with RMD. Original FAF images (A) are paired with a color-coded labeling of gray levels by quartile (B). Significant variability is observed, with multiple hyperAF and/or hypoAF dots detected within most GA lesions, especially in subjects 1, 2, 4, and 6.
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