Abstract
Purpose :
One of the earliest signs of age-related macular degeneration (AMD) is deposits in Bruch’s membrane (BM). Thus far, BM thickening has only been studied in enucleated eyes ex vivo. Here, we show that visible light Optical Coherence Tomography (OCT) imaging can resolve BM and potentially observe age-related BM thickening in pigmented mice in vivo.
Methods :
A custom spectral-domain visible light OCT ophthalmoscope was built for ultrahigh resolution in vivo mouse retinal imaging. The system had a theoretical axial resolution of 1 μm in tissue. We optimized spectrometer spectral resolution and applied spatially-dependent dispersion compensation to ensure that this resolution was achieved experimentally. Experiments were performed on 1.5 month old (n=2), 12 month old (n=2), and 18 month old (n=2) C57BL/6J mice. An incident power of 300 microwatts on the cornea and a line rate of 10 kHz were used. The imaged field-of-view was 1.44 mm (fast axis) by 0.12 mm (slow axis). Images were acquired within 2 mm of the optic disc. RPE multiply scattering tails were extrapolated and subtracted from axial intensity profiles to accurately estimate BM thickness.
Results :
Exemplary images and preliminary analysis are shown in Fig. 1 and Fig. 2. The BM band was well-separated from the RPE band in all images (Fig. 1B-D). After subtraction of RPE multiply scattering tails to yield BM axial profiles, we noticed a slight BM thickening with age (Fig. 2D-F). Interestingly, due to RPE multiple scattering, lower visibility of BM does not translate to a thicker BM.
Conclusions :
BM was visualized and quantified in vivo in highly pigmented mice of various ages with visible light OCT. This capability will enable studying BM changes with aging and ocular diseases.
This is a 2021 ARVO Annual Meeting abstract.