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Completed

NCT Number: NCT00912665

Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure

Autoregulation is defined as the ability of a vascular bed to adapt its vascular resistance to changes in perfusion pressure. In the eye, several studies have reported that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. In the optic nerve head only few data are available. Large scale studies have shown that reduced ocular perfusion pressure is an important risk factor for the prevalence, the incidence and the progression of primary open angle glaucoma.

Former studies that investigated ocular blood flow autoregulation only measured choroidal blood flow. For the optic nerve head only few data are available, although it seems likely that it underlies similar autoregulatory mechanisms.

The primary goal of the present study is to gain more insight into these phenomena in humans.

The present study aims to investigate the pressure/flow relationship as a measure for optic nerve head autoregulation during combined changes of intraocular pressure and arterial pressure. Intraocular pressure will be increased by the use of a suction cup technique, mean arterial pressure will be increased by squatting. During the whole procedure, optic nerve head blood flow will be measured continuously.

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Key information

Conditions

Healthy

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Department of Clinical Pharmacology, Medical University of Vienna

Vienna, State of Vienna, 1090, Austria

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Men and women aged between 18 and 35 years, nonsmokers
  • Men and women will be included in equal parts
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal findings in the laboratory testings unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropia less than 1 diopter

Exclusion criteria

  • Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
  • Treatment in the previous 3 weeks with any drug (except oral contraceptives)
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Blood donation during the previous 3 weeks

Treatment and study plan

Laser Doppler Flowmetry

Device

blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flow

Goldmann applanation tonometer

Device

intraocular pressure measurements

squatting

Other

Subjects will perform squatting for 6 minutes while either blood flow or intraocular pressure measurements

Suction cup

Device

Experimental stepwise increase of intraocular pressure while either optic nerve head blood flow or intraocular pressure measurements

Primary outcomes

  1. Optic nerve head pressure-flow relationship

    Time frame: in total 3x on 2 study days

Sponsors and collaborators

Lead sponsor

Medical University of Vienna

Other

Registry information

Important dates

Study start
2009
Primary completion
2010
Study completion
2010
First posted
Jun 3, 2009
Registry last updated
Aug 10, 2012

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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