July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Effect of intraocular pressure on vascular autoregulation of the mouse trilaminar network.
Author Affiliations & Notes
  • Jeremiah Kah Heng Lim
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Ronald Hao Wu
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Vickie Hoi Ying Wong
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Algis J Vingrys
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Christine Tram Oanh Nguyen
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Bang V Bui
    Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Footnotes
    Commercial Relationships   Jeremiah Lim, None; Ronald Wu, None; Vickie Wong, None; Algis Vingrys, None; Christine Nguyen, None; Bang Bui, None
  • Footnotes
    Support  Melbourne University School of Health Sciences Early Career Grant Scheme
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 4276. doi:
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      Jeremiah Kah Heng Lim, Ronald Hao Wu, Vickie Hoi Ying Wong, Algis J Vingrys, Christine Tram Oanh Nguyen, Bang V Bui; Effect of intraocular pressure on vascular autoregulation of the mouse trilaminar network.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4276.

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

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Abstract

Purpose : Previous studies have investigated the effect of intraocular pressure (IOP) elevation on the large surface vessels of the retina. It has been suggested that the capillaries are more sensitive to changes in IOP. Here, we investigate the effect of IOP elevation on the small vessels that form the superficial (SVC), intermediate (ICP) and deep (DCP) vascular plexus in the mouse eye.

Methods : Anaesthetised (80:10 mg/kg ketamine:xylazine) adult C57BL6/J mice (4-month-old, n = 10) underwent anterior chamber cannulation with a fine (50 μm) glass pipette connected to a height-adjustable saline reservoir. IOP was raised from 10 to 110 mmHg (10 mmHg steps, 3 min/step) followed by recovery back to baseline. At each step, retinal structure and blood vessels were assayed using optical coherence tomography angiography (OCTA, Spectralis OCT2) at a 20° x 10° region located one-disc diameter superior to the optic nerve margin. En face vessel maps of the SVC, ICP and DCP were extracted using the structural data to guide segmentation. OCTA images were thresholded and large vessels masked using FIJI software by a masked observer. The resultant image comprised of vessels that were 2nd order or smaller. Vessel area was obtained for each IOP step (Angiotool) and expressed relative to baseline (%). Change in layer thickness with IOP elevation was also evaluated for all retinal layers. One-way ANOVA was used to assess change in structural thickness with IOP elevation and two-way ANOVA was used to compare change in vessel layers with IOP elevation.

Results : IOP elevation produced a decrease in the vessel area of the SVC, ICP and DCP (p<0.05). Besides SVC, deeper layers (ICP and DCP) showed a trend towards increased vessel area as IOP was increased from 10 to 20 mmHg. At higher IOP levels (> 50 mmHg), SVC vessel density was less affected than ICP and DCP (p<0.05). Both ICP and DCP were similarly affected by IOP elevation (p=0.59). Structurally, there was a reduction in the thicknesses of the nerve fibre layer (93±4%, p<0.01), outer nuclear layer (88±2%, p<0.01), inner and outer plexiform layers (89±2%,95±1%, p<0.05, respectively) but not in the ganglion cell (p=0.61) and inner nuclear layer (p=0.74).

Conclusions : The data suggests that the superficial vessel complex of the mouse retina is more resistant to moderate to high IOP elevation than the intermediate and deeper capillary plexus.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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