Measurement of Total Retinal Blood Flow in Patients With Diabetes and Healthy Subjects

Inclusion Criteria: Inclusion criteria for healthy subjects * Men and women aged over 18 years * Non-smokers * Normal findings in the medical history unless the investigator considers an abnormality to be clinically irrelevant * Normal ophthalmic findings, ametropia \< 6 Dpt. Inclusion criteria for patients with diabetes * Men and women aged over 18 years * Non-smokers * Previously diagnosed type I diabetes * No or mild non-proliferative diabetic retinopathy * Normal ophthalmic findings except mild diabetic retinopathy, ametropia \< 6 Dpt. Exclusion Criteria: Any of the following will exclude a healthy subject from the study: * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * Presence or history of a severe medical condition as judged by the clinical investigator * Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study (except oral contraceptive) * Arterial hypertension (defined as either systolic blood pressure \>145 mmHg or diastolic blood pressure \>90 mmHg) * Blood donation during the previous three weeks * Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator * Best corrected visual acuity \< 0.8 Snellen * Ametropia \>= 6 Dpt * Pregnancy, planned pregnancy or lactating Any of the following will exclude a patient with diabetes from the study: * Participation in a clinical trial in the 3 weeks preceding the screening visit * Symptoms of a clinically relevant illness in the 3 weeks before the first study day * Presence or history of a severe medical condition, except diabetes, as judged by the clinical investigator * Arterial hypertension (defined as either systolic blood pressure \>145 mmHg or diastolic blood pressure \>90 mmHg) * Blood donation during the previous three weeks * Moderate to severe non-proliferative or proliferative diabetic retinopathy * Previous laser photocoagulation treatment * Presence of any abnormalities preventing reliable measurements in the study eye as judged by the investigator * Best corrected visual acuity \< 0.8 Snellen * Ametropia \>= 6 Dpt * Pregnancy, planned pregnancy or lactating