Measuring deformation in the mouse optic nerve head and peripapillary sclera

Cathy Nguyen, Dan Midgett, Elizabeth C. Kimball, Matthew R. Steinhart, Thao D. Nguyen, Mary Ellen Pease, Ericka N. Oglesby, Joan L. Jefferys, Harry A Quigley

Research output: Contribution to journalArticle

Abstract

PURPOSE. To develop an ex vivo explant system using multiphoton microscopy and digital volume correlation to measure the full-field deformation response to intraocular pressure (IOP) change in the peripapillary sclera (PPS) and in the optic nerve head (ONH) astrocytic structure. METHODS. Green fluorescent protein (GFP)-glutamate transporter-GLT1 (GLT1/GFP) mouse eyes were explanted and imaged with a laser-scanning microscope under controlled inflation. Images were analyzed for regional strains and changes in astrocytic lamina and PPS shape. Astrocyte volume fraction in seven control GLT1/GFP mice was measured. The level of fluorescence of GFP fluorescent astrocytes was compared with glial fibrillary acidic protein (GFAP) labeled astrocytes using immunohistochemistry. RESULTS. The ONH astrocytic structure remained stable during 3 hours in explants. Control strain—globally, in the central one-half or two-thirds of the astrocytic lamina—was significantly greater in the nasal-temporal direction than in the inferior-superior or anteriorposterior directions (each P ≤ 0.03, mixed models). The PPS opening (perimeter) in normal eye explants also became wider nasal-temporally than superior-inferiorly during inflation from 10 to 30 mm Hg (P = 0.0005). After 1 to 3 days of chronic IOP elevation, PPS area was larger than in control eyes (P = 0.035), perimeter elongation was 37% less than controls, and global nasal-temporal strain was significantly less than controls (P = 0.007). Astrocyte orientation was altered by chronic IOP elevation, with processes redirected toward the longitudinal axis of the optic nerve. CONCLUSIONS. The explant inflation test measures the strain response of the mouse ONH to applied IOP. Initial studies indicate regional differences in response to both acute and chronic IOP elevation within the ONH region.

Original languageEnglish (US)
Pages (from-to)721-733
Number of pages13
JournalInvestigative Ophthalmology and Visual Science
Volume58
Issue number2
DOIs
StatePublished - Feb 1 2017

Keywords

  • Collagen
  • Extracellular matrix
  • Glaucoma
  • Mouse
  • Optic nerve head
  • Retinal ganglion cell
  • Sclera

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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  • Cite this

    Nguyen, C., Midgett, D., Kimball, E. C., Steinhart, M. R., Nguyen, T. D., Pease, M. E., Oglesby, E. N., Jefferys, J. L., & Quigley, H. A. (2017). Measuring deformation in the mouse optic nerve head and peripapillary sclera. Investigative Ophthalmology and Visual Science, 58(2), 721-733. https://doi.org/10.1167/iovs.16-20620