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Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography
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Impaired increase of retinal capillary blood flow to flicker light exposure in arterial hypertension

Martin Ritt1, Joanna M Harazny, Christian Ott

  • 1Department of Nephrology and Hypertension, University of Erlangen-Nüremberg, Erlangen, Germany.

Hypertension (Dallas, Tex. : 1979)
|July 11, 2012
PubMed

Insights

The increase in retinal capillary blood flow (RCF) response to light is reduced in individuals with arterial hypertension. This impairment is not primarily driven by nitric oxide in untreated hypertensive patients.

Area of Science:

  • Ophthalmology
  • Cardiovascular Science
  • Medical Physiology

Background:

  • Arterial hypertension is a significant cardiovascular risk factor.
  • Retinal microvascular function may be compromised in hypertension.
  • Assessing retinal capillary blood flow (RCF) changes to stimuli can reveal vascular dysfunction.

Purpose of the Study:

  • To investigate the hypothesis that the increase in RCF in response to flicker light is impaired in subjects with arterial hypertension.
  • To explore the role of nitric oxide in this response.

Main Methods:

  • Noninvasive in vivo measurement of RCF using scanning laser Doppler flowmetry in 146 nondiabetic untreated males (50 with hypertension, 96 controls).
  • RCF was measured before and after flicker light exposure.
  • In a subgroup of 28 subjects, the response was re-assessed during nitric oxide synthase inhibition with N-monomethyl-L-arginine (L-NMMA).

Main Results:

  • The increase in RCF to flicker light was significantly lower in hypertensive subjects compared to normotensive controls, both in absolute and percentage terms (P adjusted=0.013 and P adjusted=0.023, respectively).
  • Systolic blood pressure was negatively correlated with the percent change in RCF, independent of other risk factors.
  • The RCF response to flicker light was similar with or without L-NMMA infusion, indicating nitric oxide is not a major determinant.

Conclusions:

  • The increase in retinal capillary blood flow in response to flicker light is impaired in individuals with untreated arterial hypertension.
  • Nitric oxide does not appear to be a primary mediator of this flicker-induced RCF increase in the study population.

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