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E. Tsui, M. Sehi, J. Wan, T. Wong, S. Dorner, J. Fisher, C. Hudson; Relative Vascular Reactivity in the Major Retinal Arterioles. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3444. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the magnitude of retinal vascular reactivity in response to metabolic provocation at equivalent measurement sites in the superior and inferior temporal arterioles of the retina.
One randomly selected eye of each of 10 healthy volunteers (age 22.6±3.1) was prospectively enrolled. Volunteers were connected to a sequential gas delivery circuit (RespirActTM, Thornhill Research Inc., Toronto, Canada) and underwent a gas provocation protocol consisting of 2 phases. Baseline was achieved with gas flow adjusted to a PETCO2 of 38mmHg. Hyperoxia was achieved at a PETO2 of 500mmHg with PETCO2 clamped at 38mmHg. Four flow measurements were acquired of the superior temporal (STA) and of the inferior temporal arterioles (ITA), using the Canon Laser Blood Flowmeter (CLBF-100, Canon, Japan), at equivalent positions during the baseline and hyperoxic phases. Linear mixed-effect models for repeated measures using JMP software (v. 8.0, SAS Inc., Cary, NC) were performed.
The diameter, velocity and flow were the same between the STA and ITA at the baseline (p=0.1, p=0.5, p=0.1 respectively) and hyperoxic phases (p=0.2, p=0.2, p=0.2), respectively. During the hyperoxic phase, the vessel diameter, centerline velocity and blood flow decreased in the STA (p=0.02, p<0.001, p<0.001, respectively) and the ITA (p=0.02, p=0.003, p=0.007, respectively). The amount of change in diameter due to hyperoxia was not different between the STA and ITA (p = 0.5) and was not associated with age (p=0.3) or gender (p=0.8). The amount of change in velocity due to hyperoxia was not different between the STA and ITA (p=0.70) and was associated with age (p=0.02) but not gender (p=0.4). The amount of change in flow due to hyperoxia was not different between the STA and ITA (p=0.2) and was not associated with age (p=0.9), or gender (p=0.5).
The magnitude of vascular reactivity of the superior temporal and inferior temporal arterioles in response to metabolic provocation is similar at equivalent measurement sites. This implies that the vascular regulatory response of the retinal arterioles can be reasonably derived from a single measurement site, assuming that the vascular insult itself was not localized.
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