In vivo imaging of Schlemm’s canal and limbal vascular network in mouse using visible-light OCT

Xian Zhang, Lisa Beckmann, David A. Miller, Guangbin Shao, Zhen Cai, Cheng Sun, Nader Sheibani, Xiaorong Liu, Joel Schuman, Mark Johnson, Tsutomu Kume, Hao F. Zhang

    Research output: Contribution to journalArticlepeer-review

    Abstract

    PURPOSE. To validate the ability of visible-light optical coherence tomography (vis-OCT) in imaging the full Schlemm’s canal (SC) and its surrounding limbal vascular network in mice in vivo through a compound circumlimbal scan. METHODS. We developed an anterior segment vis-OCT system and a compound circumlimbal scanning method, which montages eight rotated raster scans. We calibrated the circumlimbal scan geometry using a three-dimensional printed phantom eyeball before imaging wild-type C57BL/6J mice. We measured SC size by segmenting SC cross sections from vis-OCT B-scan images and imaged the limbal microvascular network using vis-OCT angiography (vis-OCTA). To introduce changes in SC size, we used a manometer to adjust the intraocular pressure (IOP) to different levels. To create additional optical scattering contrast to enhance SC imaging, we surgically increased the episcleral venous pressure (EVP) and caused blood reflux into SC. RESULTS. Using the compound circumlimbal scan, our anterior segment vis-OCT noninvasively imaged the full SC and limbal microvascular network in mouse for the first time. We observed an average 123% increase in SC volume when we decreased the IOP by 10 mm Hg from the baseline IOP of 7 to 10 mm Hg and an average 72% decrease in SC volume when the IOP level was elevated by 10 mm Hg from the baseline IOP. We also observed location-dependent SC size responses to IOP changes. Blood reflux caused by increased EVP enabled vis-OCTA to directly visualize SC, which matched well with the segmented SC. CONCLUSIONS. Vis-OCT and vis-OCTA can accurately image the entire SC and limbal microvascular network in vivo using the compound circumlimbal scan. Vis-OCT is also able to quantitatively measure SC responses to changing IOP levels.

    Original languageEnglish (US)
    Article number2761682
    JournalInvestigative Ophthalmology and Visual Science
    Volume61
    Issue number2
    DOIs
    StatePublished - Feb 2020

    Keywords

    • Angiography
    • Optical coherence tomography
    • Schlemm’s canal

    ASJC Scopus subject areas

    • Ophthalmology
    • Sensory Systems
    • Cellular and Molecular Neuroscience

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