June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Corneal hysteresis predicts optic nerve tissue displacement in response to acute IOP elevation
Author Affiliations & Notes
  • Bang V Bui
    Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Fumi Tanabe
    Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Phillip Bedggood
    Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Andrew Turpin
    Department of Computing and Information Systems, The University of Melbourne, Parkville, Victoria, Australia
  • Andrew J Anderson
    Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Allison Maree McKendrick
    Optometry & Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia
  • Footnotes
    Commercial Relationships   Bang Bui, None; Fumi Tanabe, None; Phillip Bedggood, None; Andrew Turpin, None; Andrew Anderson, None; Allison McKendrick, None
  • Footnotes
    Support  Australian Research Council (FT130100338)
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3138. doi:
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      Bang V Bui, Fumi Tanabe, Phillip Bedggood, Andrew Turpin, Andrew J Anderson, Allison Maree McKendrick; Corneal hysteresis predicts optic nerve tissue displacement in response to acute IOP elevation. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3138.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To determine if corneal hysteresis is predictive of the response of the healthy optic nerve to acute elevation of intraocular pressure (IOP)

Methods : Corneal hysteresis (average of 3 readings) was measured using the ocular response analyzer (ORA) for eight healthy participants (mean [SD], 32.5 [8.2] years). The left eye was imaged with spectral-domain optical coherence tomography (Spectralis, EDI mode, ART11, 10x15 degrees scan optic nerve centered) at baseline and during acute IOP elevation; achieved using an ophthalmodynamometer held perpendicular to the globe via the inferior lid. Target force (300-400 mN) was maintained via feedback from force transducer to a linear motor, affording stable IOP (within 2 mmHg) during imaging. IOP was measured using a rebound tonometer (5 readings) immediately after the baseline scan and during IOP elevation immediately prior to imaging. A masked grader manually segmented the anterior laminar surface in a vertical B-scan. This was referenced to Bruch’s membrane opening in the same scan. The enface infrared image was analysed to demarcate the nasal cup edge as defined by the nasal blood vessels. Maximal anterior laminar displacement (ALD) and nasal cup edge displacement (NCD) were returned by taking the diffference between baseline and high IOP conditions and correlated with corneal hysteresis.

Results : Corneal hysteresis was 10.7±1.3 (range 9.1-12.9). A force of 300-400mN applied through the lower lid resulted in significant IOP elevation (baseline: 14.2±5.2, high IOP: 26.5±7.0mmHg). Acute mild IOP elevation produced significant deformation of the anterior laminar surface and the nasal edge of the cup. IOP elevation produced a maximal ALD of 162±170μm and NCD of -18.1±21.7μm. Univariate analysis shows that there was a significant correlation between displacement of the anterior laminar cribrosa (displacement = -93.7*(hysteresis)+1162, r2=0.56, p=0.03) or nasal edge of the cup (displacement = 13.6*(hysteresis)–162.9, r2=0.67, p=0.014) and corneal hysteresis.

Conclusions : Corneal hysteresis is predictive of anterior lamina cribrosa deformation, and nasal optic nerve blood vessels shifts, in response to acute IOP elevation. Our results raise the possibility that important dynamic responses of the optic nerve related to disease development, and typically only measurable with customised research tools, might be usefully predicted by simple clinical measures.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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