Measuring in-vivo and in-situ ex-vivo the 3D deformation of the lamina cribrosa microstructure under elevated intraocular pressure

Junchao Wei, Bin Yang, Andrew P. Voorhees, Huong Tran, Bryn Brazile, Bo Wang, Joel Schuman, Matthew A. Smith, Gadi Wollstein, Ian A. Sigal

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Elevated intraocular pressure (IOP) deforms the lamina cribrosa (LC), a structure within the optic nerve head (ONH) in the back of the eye. Evidence suggests that these deformations trigger events that eventually cause irreversible blindness, and have therefore been studied in-vivo using optical coherence tomography (OCT), and ex-vivo using OCT and a diversity of techniques. To the best of our knowledge, there have been no in-situ ex-vivo studies of LC mechanics. Our goal was two-fold: to introduce a technique for measuring 3D LC deformations from OCT, and to determine whether deformations of the LC induced by elevated IOP differ between in-vivo and in-situ ex-vivo conditions. A healthy adult rhesus macaque monkey was anesthetized and IOP was controlled by inserting a 27- gauge needle into the anterior chamber of the eye. Spectral domain OCT was used to obtain volumetric scans of the ONH at normal and elevated IOPs. To improve the visibility of the LC microstructure the scans were first processed using a novel denoising technique. Zero-normalized cross-correlation was used to find paired corresponding locations between images. For each location pair, the components of the 3D strain tensor were determined using non-rigid image registration. A mild IOP elevation from 10 to 15mmHg caused LC effective strains as large as 3%, and about 50% larger in-vivo than in-situ ex-vivo. The deformations were highly heterogeneous, with substantial 3D components, suggesting that accurate measurement of LC microstructure deformation requires high-resolution volumes. This technique will help improve understanding of LC biomechanics and how IOP contributes to glaucoma.

    Original languageEnglish (US)
    Title of host publicationOptical Elastography and Tissue Biomechanics V
    EditorsDavid D. Sampson, Kirill V. Larin
    PublisherSPIE
    ISBN (Electronic)9781510614772
    DOIs
    StatePublished - 2018
    EventOptical Elastography and Tissue Biomechanics V 2018 - San Francisco, United States
    Duration: Jan 27 2018Jan 28 2018

    Publication series

    NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
    Volume10496
    ISSN (Print)1605-7422

    Conference

    ConferenceOptical Elastography and Tissue Biomechanics V 2018
    CountryUnited States
    CitySan Francisco
    Period1/27/181/28/18

    Keywords

    • OCT
    • deformation
    • glaucoma
    • image registration
    • lamina cribrosa

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Biomaterials
    • Atomic and Molecular Physics, and Optics
    • Radiology Nuclear Medicine and imaging

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