the measuring points. The velocity of the moving hypoßuorescent segments was calculated as v = Ds/Dt. The assessment of the capillary ßow velocities was performed in each patient in 15 different vessels. All measurements were performed in the monolayer capillary network preventing confounding errors from oblique vessels. The velocity of ten different segments of low and high ßuorescence in each capillary is quantiÞed. Every value of the mean blood ßow velocity (v) is based on 150 single measurements. All of these are performed within a time period of less than 5 s in the early transit phase of the angiograms. Measurements of actual distances were corrected for the refractive error.

5.2Normal Values

Fluorescein angiograms of 221 healthy volunteers(116male;105female,age:30.9 ± 12.8years) were performed to establish reference values for the arm-retina time, arteriovenous passage time, and mean arterial dye velocity (Table 5.1).

The interindividual variation was calculated and showed a 24% variation for the arm-retina time, a 27% variation for the arteriovenous passage time, and a 24% variation for the mean arterial dye velocity. The correlation between the arm-retina time and the arteriovenous passage time was weak (r = 0.17; p < 0.05). With increasing mean arterial dye velocity, a decrease of the arteriovenous passage time was noted (r = −0.31; p < 0.01).

In a group of 90 healthy subjects, ßuorescein angiography for assessment of capillary ßow parameters was performed. The capillary ßow velocity was 2.89 ± 0.41 mm/s. The interindividual variation of the capillary ßow velocity was 14.2%. With increasing arteriovenous passage

time, the capillary ßow velocity decreased slightly (r = −0.25; p < 0.05).

The inßuence of age, blood pressure, heart rate, and intraocular pressure was evaluated by multiple stepwise regression analysis. A signiÞcant relation between age and arm-retina time (r = 0.331; p < 0.01) and arteriovenous passage time (r = 0.164; p < 0.01) was found. Both armretina time and arteriovenous passage time were observed to increase slightly with age. Blood pressure, pulse rate, and intraocular pressure showed no additional signiÞcant inßuence on the dynamic data. Comparing the 10% youngest and oldest subjects (age: 21 ± 1 years vs. 63 ± 8 years), no signiÞcant differences could be found between the two groups (arteriovenous passage time: 1.6 ± 0.4 s vs. 1.7 ± 0.4 s, p > 0.05).

The mean capillary ßow velocity showed a dependence on age (r = −0.296; p < 0.01). The mean capillary ßow velocity decreased with increasing age. No additional signiÞcant inßuence of the blood pressure, heart rate, and intraocular pressure was found.

5.3Retinal Pathologies

5.3.1Diabetes Mellitus

Bertram et al. [11] report retinal blood ßow data from a study in patients with diabetic retinopathy. For this study, the system described above was used. In a group of 124 patients, with type I diabetes mellitus (71 male, 53 female age: mean 35 ± 12 years), retinal circulation times were assessed. The severity of diabetic retinopathy was evaluated by ophthalmoscopy, fundus photography, and angiography. The diabetic patients were distributed into four groups: (1) no retinopathy (no DR); (2) mild to moderate nonproliferative