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. 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. There is also evidence that autoregulation is impaired in patients with primary open angle glaucoma.

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

The present study aims to investigate the pressure/flow relationship as a measure for retinal blood flow autoregulation during an experimental increase in intraocular pressure by the use of the suction cup technique. Retinal blood flow will be measured by Doppler OCT.

Inclusion Criteria:

• Men and women aged between 18 and 35 years
• Non-smokers
• Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant
• Normal ophthalmic findings, ametropy < 1 Dpt.

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 contraceptives)
• Symptoms of a clinically relevant illness in the 3 weeks before the first study day
• Blood donation during the previous 3 weeks
• Pregnancy, planned pregnancy or lactating

16 healthy subjects