Tong Yuehong, Ach Thomas, Curcio Christine A, Smith R Theodore
Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Department of Ophthalmology, University Hospital Bonn, Germany.
Ann Eye Sci. 2021 Mar;6. doi: 10.21037/aes-20-12. Epub 2021 Mar 15.
Soft drusen and basal linear deposit (BLinD) are two forms of the same extracellular lipid rich material that together make up an Oil Spill on Bruch's membrane (BrM). Drusen are focal and can be recognized clinically. In contrast BLinD is thin and diffusely distributed, and invisible clinically, even on highest resolution OCT, but has been detected on hyperspectral autofluorescence (AF) imaging . We sought to optimize histologic hyperspectral AF imaging and image analysis for recognition of drusen and sub-RPE deposits (including BLinD and basal laminar deposit), for potential clinical application.
Twenty locations specifically with drusen and 12 additional locations specifically from fovea, perifovea and mid-periphery from RPE/BrM flatmounts from 4 AMD donors underwent hyperspectral AF imaging with 4 excitation wavelengths (λ 436, 450, 480 and 505 nm), and the resulting image cubes were simultaneously decomposed with our published non-negative matrix factorization (NMF). Rank 4 recovery of 4 emission spectra was chosen for each excitation wavelength.
A composite emission spectrum, sensitive and specific for drusen and presumed sub-RPE deposits (the SDr spectrum) was recovered with peak at 510-520 nm in all tissues with drusen, with greatest amplitudes at excitations λ 436, 450 and 480 nm. The RPE spectra of combined sources Lipofuscin (LF)/Melanolipofuscin (MLF) were of comparable amplitude and consistently recapitulated the spectra S1, S2 and S3 previously reported from all tissues: tissues with drusen, foveal and extra-foveal locations.
A clinical hyperspectral AF camera, with properly chosen excitation wavelengths in the blue range and a hyperspectral AF detector, should be capable of detecting and quantifying drusen and sub-RPE deposits, the earliest known lesions of AMD, before any other currently available imaging modality.
软性玻璃膜疣和基底线性沉积物（BLinD）是同一富含细胞外脂质物质的两种形式，它们共同构成了 Bruch 膜（BrM）上的“油溢”现象。玻璃膜疣是局灶性的，临床可识别。相比之下，BLinD 薄且呈弥漫性分布，临床不可见，即使在最高分辨率的光学相干断层扫描（OCT）上也看不到，但在高光谱自发荧光（AF）成像中已被检测到。我们试图优化组织学高光谱 AF 成像和图像分析，以识别玻璃膜疣和视网膜色素上皮（RPE）下沉积物（包括 BLinD 和基底膜状沉积物），用于潜在的临床应用。
对来自 4 名年龄相关性黄斑变性（AMD）供体的 RPE/BrM 平铺标本中 20 个有玻璃膜疣的特定位置以及另外 12 个来自中央凹、中央凹周围和中周部的特定位置，用 4 种激发波长（λ 436、450、480 和 505 nm）进行高光谱 AF 成像，并用我们已发表的非负矩阵分解（NMF）方法对所得图像立方体进行同时分解。为每个激发波长选择秩为 4 的 4 个发射光谱恢复。
在所有有玻璃膜疣的组织中，恢复了对玻璃膜疣和推测的 RPE 下沉积物敏感且特异的复合发射光谱（SDr 光谱），其峰值在 510 - 520 nm，在激发波长λ 436、450 和 480 nm 处幅度最大。联合来源脂褐素（LF）/黑素脂褐素（MLF）的 RPE 光谱幅度相当，并始终重现了先前从所有组织（有玻璃膜疣的组织、中央凹和中央凹外位置）报道的光谱 S1、S2 和 S3。
一台临床高光谱 AF 相机，在蓝色范围内适当选择激发波长并配备高光谱 AF 探测器，应该能够在任何其他现有成像方式之前检测和量化玻璃膜疣和 RPE 下沉积物，即 AMD 最早已知的病变。
