Seeing the hidden lamina: Effects of exsanguination on the optic nerve

Head Huong Tran, Jacob Wallace, Ziyi Zhu, Katie A. Lucy, Andrew P. Voorhees, Samantha E. Schmitt, Richard A. Bilonick, Joel S. Schuman, Matthew A. Smith, Gadi Wollstein, Ian A. Sigal

    Research output: Contribution to journalArticle

    Abstract

    PURPOSE. To introduce an experimental approach for direct comparison of the primate optic nerve head (ONH) before and after death by exsanguination. METHOD. The ONHs of four eyes from three monkeys were imaged with spectral-domain optical coherence tomography (OCT) before and after exsanguination under controlled IOP. ONH structures, including the Bruch membrane (BM), BM opening, inner limiting membrane (ILM), and anterior lamina cribrosa (ALC) were delineated on 18 virtual radial sections per OCT scan. Thirteen parameters were analyzed: scleral canal at BM opening (area, planarity, and aspect ratio), ILM depth, BM depth; ALC (depth, shape index, and curvedness), and ALC visibility (globally, superior, inferior, nasal, and temporal quadrants). RESULTS. All four ALC quadrants had a statistically significant improvement in visibility after exsanguination (overall P < 0.001). ALC visibility increased by 35% globally and by 36%, 37%, 14%, and 4% in the superior, inferior, nasal, and temporal quadrants, respectively. ALC increased 4.1%, 1.9%, and 0.1% in curvedness, shape index, and depth, respectively. Scleral canals increased 7.2%, 25.2%, and 1.1% in area, planarity, and aspect ratio, respectively. ILM and BM depths averaged −7.5% and −55.2% decreases in depth, respectively. Most, but not all, changes were beyond the repeatability range. CONCLUSIONS. Exsanguination allows for improved lamina characterization, especially in regions typically blocked by shadowing in OCT. The results also demonstrate changes in ONH morphology due to the loss of blood pressure. Future research will be needed to determine whether there are differences in ONH biomechanics before and after exsanguination and what those differences would imply.

    Original languageEnglish (US)
    Pages (from-to)2564-2575
    Number of pages12
    JournalInvestigative Ophthalmology and Visual Science
    Volume59
    Issue number6
    DOIs
    StatePublished - May 2018

    Keywords

    • Blood vessel shadow
    • Exsanguination
    • Lamina cribrosa
    • OCT
    • Optic nerve head

    ASJC Scopus subject areas

    • Ophthalmology
    • Sensory Systems
    • Cellular and Molecular Neuroscience

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  • Cite this

    Tran, H. H., Wallace, J., Zhu, Z., Lucy, K. A., Voorhees, A. P., Schmitt, S. E., Bilonick, R. A., Schuman, J. S., Smith, M. A., Wollstein, G., & Sigal, I. A. (2018). Seeing the hidden lamina: Effects of exsanguination on the optic nerve. Investigative Ophthalmology and Visual Science, 59(6), 2564-2575. https://doi.org/10.1167/iovs.17-23356