Some of the most prevalent eye diseases such as age-related macular degeneration, glaucoma and diabetic retinopathy are associated with ocular perfusion abnormalities. Currently, there is no gold-standard method for the measurement of ocular blood flow available. Laser speckle flowgraphy is a promising technique for the two-dimensional assessment of ocular blood flow in humans. So far the technique has, however, been only gained widespread use in Japan. The experience in Caucasian subjects is very limited. In a Japanese population it was shown that mean blur rate, a measure of chorioretinal blood velocity, decreases with age. This is of relevance, because an age-related decline in ocular blood flow may partially explain the age-dependence of ocular vascular disease. The present study investigates this age-dependence in healthy subjects. In addition, the investigators investigate in a sub-group of this population whether relative flow volume (RFV), a novel index of blood flow in the human retina derived from laser speckle flowgraphy is associated with retinal blood flow as assessed with bi-directional Doppler Optical Coherence Tomography (DOCT).

Inclusion Criteria:

• Men and women aged over 18 years, nonsmokers
• Subject is generally healthy with no current significant or a history of a significant neurological, cardiovascular, pulmonary (including asthma), hepatic, metabolic, rheumatic, autoimmune, hematological or renal disorder, as determined by the investigator's clinical judgment through collection of medical history and performance of a physical examination. A significant disorder is defined as a disease or medical condition associated with impaired health status, requiring regular or current medical treatment and/or follow up. For the purposes of this study, an investigator may classify a medical condition as a nonsignificant disorder despite the fact that the subject receives treatment. Subjects having controlled Stage 1 hypertension (blood pressure of 140-159 mmHg systolic and/or 90- 99 mmHg diastolic) are eligible for participation in this study.
• Normal ophthalmic findings, ametropia < 6 Dpt

Exclusion Criteria:

• Symptoms of a clinically relevant illness in the 3 weeks before the first study day
• Wearing of contact lenses
• Ocular infection or clinically significant inflammation
• Ocular surgery in the 3 months preceding the study
• Blood donation in the 3 weeks preceding the study
• Pregnancy, planned pregnancy or lactating
• Opacities of the cornea (e.g. corneal scars, corneal oedema), the lens (e.g. Lens opacities classification system version II (LOCS-II) grading > 2, posterior capsule opacification) or the vitreous (e.g. vitreous haemorrhage, asteroid hyalosis)

80 healthy subjects in 4 age groups Group 1: 18-34 years Group 2: 35-49 years Group 3: 50-64 years Group 4: 65-80 years