CO2 dependence of retinal arterial and capillary blood velocity

Alon Harris, O. Arend, S. Wolf, Louis Cantor, B. J. Martin

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

Objective: Blood flow to the brain is extremely sensitive to changes in PCO2. While animal studies show a similar potent PCO2 dependence in retinal and choroidal vessels, the PCO2-retinal blood flow relationship has never been adequately studied in humans. Methods: Video scanning laser ophthalmoscopy after fluorescein angiography was used to analyze retinal arterial and capillary blood velocity under conditions of mild hypercapnia and hypocapnia. Control conditions (end-tidal PCO2 = 38.3 ± 0.4 mmHg) were contrasted with hyperventilation-induced hypocapnia (PCO2 = 34.0 ± 0.4 mmHg) and hypercapnia (PCO2 = 42.3 ± 0.5 mmHg) created by PCO2 addition to inspired gas. Results: Both larger vessel and macular capillary blood velocity was dependent upon PCO2: arteriovenous passage time fell as PCO2 rose, and both mean arterial dye velocity and capillary blood velocity rose as PCO2 rose (all p < 0.05). These changes in flow velocity occurred despite unchanged heart rate, arterial systolic and diastolic blood pressure, intraocular pressure, and calculated ocular perfusion pressure. Contrast sensitivity was also unchanged by PCO2 variation. Conclusions: The human retinal circulation, like the whole cerebral circulation, may be strongly dependent upon PCO2 in a manner that is unrelated to perfusion pressure and apparently outside strict autoregulatory controls.

Original languageEnglish
Pages (from-to)421-424
Number of pages4
JournalActa Ophthalmologica Scandinavica
Volume73
Issue number5
StatePublished - 1995

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Hypocapnia
Hypercapnia
Cerebrovascular Circulation
Perfusion
Blood Pressure
Pressure
Ophthalmoscopy
Retinal Vessels
Contrast Sensitivity
Hyperventilation
Fluorescein Angiography
Intraocular Pressure
Lasers
Coloring Agents
Heart Rate
Gases
Brain

Keywords

  • Angiography
  • Blood flow
  • Carbon dioxide
  • Contrast sensitivity
  • Retina

ASJC Scopus subject areas

  • Ophthalmology

Cite this

CO2 dependence of retinal arterial and capillary blood velocity. / Harris, Alon; Arend, O.; Wolf, S.; Cantor, Louis; Martin, B. J.

In: Acta Ophthalmologica Scandinavica, Vol. 73, No. 5, 1995, p. 421-424.

Research output: Contribution to journalArticle

Harris, Alon ; Arend, O. ; Wolf, S. ; Cantor, Louis ; Martin, B. J. / CO2 dependence of retinal arterial and capillary blood velocity. In: Acta Ophthalmologica Scandinavica. 1995 ; Vol. 73, No. 5. pp. 421-424.
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