May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Limits of Choroidal Autoregulation in Healthy Humans
Author Affiliations & Notes
  • E. A. Polska
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
  • J. Kolodjaschna
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
  • C. Simader
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
    Ophthalmology,
  • F. Berisha
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
  • K. Karl
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
  • A. Luksch
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
    Ophthalmology,
  • G. Fuchsjaeger-Mayrl
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
    Ophthalmology,
  • L. Schmetterer
    Medical University of Vienna, Vienna, Austria
    Clinical Pharmacology,
    Center for Biomedical Engineering and Physics,
  • Footnotes
    Commercial Relationships E.A. Polska, None; J. Kolodjaschna, None; C. Simader, None; F. Berisha, None; K. Karl, None; A. Luksch, None; G. Fuchsjaeger-Mayrl, None; L. Schmetterer, None.
  • Footnotes
    Support None.
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 2267. doi:
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      E. A. Polska, J. Kolodjaschna, C. Simader, F. Berisha, K. Karl, A. Luksch, G. Fuchsjaeger-Mayrl, L. Schmetterer; Limits of Choroidal Autoregulation in Healthy Humans. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2267.

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

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Abstract

Purpose:: The aim of this study was to evaluate physiologic autoregulatory capacity of the human choroid during changes in ocular perfusion pressure using data from studies previously performed in our lab.

Methods:: The lower and upper limits of choroidal autoregulation were studied in healthy male non-smokers, 19 - 35 years old. Intraocular pressure was artificial elevated using the suction cup method. A change in systemic arterial blood pressure was induced by isometric exercise (squatting). Choroidal blood flow was assessed using laser Dopler flowmetry. Intraocular pressure was measured with an applanation tonometer. Mean brachial artery blood pressures (MAP) were measured on the upper arm by an automated oscillometric device. Ocular perfusion pressure was calculated as 2/3MAP - IOP. The main outcome parameter was the relationship between ocular perfusion pressure and choroidal blood flow. Data from eight different studies were collected. Only data obtained during periods without any drugs were included.

Results:: The suction cup was applied to eighty three volunteers. During an artificial IOP rise the choroid maintains its blood flow almost constant up to 30% reduction in ocular perfusion pressure. Ninety six subjects performed squatting. During isometric exercise the upper limit of autoregulation appears to be approximately 60% above the baseline ocular perfusion pressure.

Conclusions:: The choroid is able to maintain its blood flow almost constant during wide range of ocular perfusion pressure. However, relatively large inter-individual differences could be observed. Moreover, changes in choroidal circulation were sooner dependent on IOP values and showed only little association with MAP.

Clinical Trial:: retrospective analysis of data

Keywords: choroid • blood supply • intraocular pressure 
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