Abstract
Purpose :
As one part of the central nervous system, the retina manifests neuronal dysfunction and vascular abnormality in neurodegenerative diseases, such as Alzheimer’s disease (AD). Early studies demonstrated that the pathological hallmarks appear selective to the retinal quadrant. This study aims to demonstrate in vivo optical coherence tomography (OCT) and OCT angiography (OCTA) monitoring of all quadrants of the neurodegenerative mouse retina.
Methods :
Six-month-old 5xFAD (TG, N = 5) and wild-type mice (WT, N = 6) were used in this study. A custom-built OCT system (λ = 810 nm) was used for retinal imaging. Volumetric raster scans were acquired in 4 retinal quadrants (nasal, dorsal, temporal, ventral) per mouse. Each volume consisted of 4 × 500 × 500 A-scans. Four repeated B-scans at each slow scan position were collected for OCTA construction. For quantitative analysis, we measured retinal thickness, vascular width, and vascular density. The artery and vein around the ONH were classified for width measurement. Retinal vascular layers were segmented into superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) for density measurement.
Results :
Wide-field OCT and OCTA images were constructed by stitching 4 retinal volumes obtained from 4 different quadrants (Fig. 1), and each OCT/OCTA volume was individually analyzed for quantitative assessment. Inner retinal and outer retinal thickness were notably reduced in the dorsal and temporal quadrants of TG mice. Accordingly, whole retinal thickness was significantly lower in TG mice compared to WT mice (TG: 223.8 ± 5.3 μm; WT: 229.5 ± 4.7 μm; P < 0.001). A significant arterial narrowing in TG mice was also found (TG: 28.3 ± 4.8 μm; WT: 33.6 ± 4.7 μm; P < 0.0001). In addition, vessel densities in three plexuses were consistently low in TG mice. Especially, the ICP density reduction in TG mice was close to being statistically significant (TG: 13.7 ± 2.6%; WT: 14.8 ± 2.3%; P = 0.056), which suggests a tight correlation between neuronal and vascular degeneration.
Conclusions :
In this study, we demonstrated wide-field OCT/OCTA monitoring of all retinal quadrants, which allowed to examine regional changes in the retina due to neurodegeneration. The wide field OCT/OCTA provides an imaging platform for longitudinal monitoring of AD-associated retinal degeneration and noninvasive assessment of therapy protocols.
This is a 2021 ARVO Annual Meeting abstract.