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

Medical University of Vienna

Status: Completed

Conditions: Healthy

Treatments: Other: squatting; Device: Suction cup; Device: Goldmann applanation tonometer; Device: Laser Doppler Flowmetry

Study type: Interventional

Funder types: Other

Identifiers

NCT00912665

OPHT-150808

Details and patient eligibility

About

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.

Enrollment: 40 patients

Sex: All

Ages: 18 to 35 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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40 participants in 1 patient group

Healthy Volunteer

Experimental group

Treatment:

Device: Goldmann applanation tonometer

Other: squatting

Device: Laser Doppler Flowmetry

Device: Suction cup