Work

Imaging oxygenation of retinal capillaries with depth resolution

Year: 2020

Type: article

Abstract: The inner retina has a three-tiered vascular supply, with capillary beds stratifying in the nerve fiber layer/ganglion cell layer, the inner plexiform layer, and the outer plexiform layer (1). While this trilaminar architecture likely functions to serve the metabolic needs of individual retinal layers, we do not know how metabolism and blood flow regulation differ across layers in the healthy retina. In particular, no noninvasive imaging technique with the potential for human translation has yet successfully distinguished the subtle metabolic signals that arise from these thin layers. For the past decade, visible light optical coherence tomography (OCT) (2, 3) has held the promise of imaging retinal oxygenation based on hemoglobin absorption. However, efforts have been largely limited to quantifying oxygenation of large vessels (4), with rare exceptions (5). In their latest work, Pi et al. (6) take a step toward making visible light OCT a tool for studying depth-resolved oxygenation of retinal capillary beds. First, they show that their oximetry method is highly repeatable, a must for any measurement to make it to the clinic. Next, they turn their attention toward accuracy. The closest analog of a retinal capillary saturation measurement is a phosphorescence lifetime-based oxygen tension probe (7) or invasive tissue oxygen electrodes (8). How does one validate a technique for which there is no direct and noninvasive gold standard? The authors propose a creative, albeit indirect, method to gauge accuracy. As noted previously by the authors (9), the superficial vascular plexus supply in Brown Norway rats appears to consist predominantly of arterioles and their higher-order two-dimensional capillary branches that supply the surrounding tissue. In this model vascular bed (Fig. 1 … [↵][1]1To whom correspondence may be addressed. Email: vjsriniv{at}ucdavis.edu. [1]: #xref-corresp-1-1

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.2008404117

Authors: Vivek J. Srinivasan, Ala Moshiri

Institutions: University of California Davis Medical Center, University of California, Davis

Language: English

Topic: Optical Coherence Tomography Applications

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: green

Funders: Glaucoma Research Foundation, National Eye Institute, National Institute of Neurological Disorders and Stroke, National Institute of Biomedical Imaging and Bioengineering