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Yuehong Tong, Thomas Ach, Christine Curcio, R Theodore Smith; New findings in Hyperspectral Autofluorescence (AF) imaging of donor eyes with Age-related Macular Degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2020;61(7):1823.
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To find the hyperspectral AF signatures of basal laminar deposit (BLamD) and ectopic retinal pigment epithelium (RPE), the latter corresponding to clinical hyper-reflective foci (HRF) of AMD prognostic import.
Fixed retinal cross-sections (CS) from 2 AMD donors and one normal control underwent microscopic hyperspectral AF imaging (40X oil objective, numerical aperture = 0.75) at 12 locations with 4 excitation wavelengths (436, 450, 480 and 505 nm), and emissions recorded from 420 to 700 nm. The images were decomposed with rank 2 non-negative matrix factorization (NMF) to recover 2 emission spectra and their corresponding localizations.
The 2 major spectra recovered were a short wavelength (SW) composite (mean peak 513 +/- 5 nm) localized to RPE and BrM and a long wavelength (LW) spectrum specific to RPE (mean peak, 570 nm), essentially identical to S2 reported in RPE-Bruch’s membrane (BrM) flat mounts (Ben Ami et al., PMID 27226929). In AMD tissues, SW sources also included drusen (Tong et al, Retina, 2016) and BLamD. Figure 1 shows an exemplary panchromatic AF, or “RGB” image, recovered spectra and their corresponding abundance images. The isolated spectral emission of BLamD, read directly from 6 tissue bands, peaked at 513 +/- 10 nm, essentially identical to the NMF SW spectrum. Eleven ectopic RPE cells in the neural retina of 1 eye displayed a higher ratio (1.7) of SW emissions to LW emissions relative to orthotopic RPE (0.9) (Figure 2).
The spectral AF of BLamD peaks around 513 nm along with drusen and disparate other SW emitters on CS, molecular sources to be determined. The spectral shift from orthotopic to ectopic RPE suggests significant loss or degradation of LW sources (lipofuscin and melanolipofuscin) in ectopic RPE, and may reflect the RPE stress that drives it to leave its layer and form clinical HRF.
This is a 2020 ARVO Annual Meeting abstract.
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