[Absolute blood flow in the ophthalmic artery]

Knowledge about the total blood flow in the ophthalmic artery (OA) is very important in some ocular disorders. We estimated the total blood flow (BF) in the OA by measuring simultaneously the inner diameter of the OA (Doph) and the mean blood velocity (VMmean) of the same OA. Doph in [mm] was estimated with digitalized subtraction angiography (DSA) of the OA. The blood velocity was measured by pulsed Doppler sonography (4 MHz, 39 +/- 4 mm orbital depth, sample volume 4 mm, EME, Uberlingen). In addition to the pulse curve outline formed by the peak velocities, a pulse curve mean line was established as formed by mathematical integration of the relative strengths of all velocities at given time point. This pulse curve mean line resembles the mean velocity of all red blood cells in the OA at any time during the heart cycle with a systolic maximum (VMsys), a diastolic minimum (VMdia) and a mean blood velocity (VMmean). The pulse curve mean line always shows lower velocities than the pulse curve outline. The total blood flow (BF) in ml/min in the OA was calculated by: BF = (Doph/2)2 x 3.14 x VMmean. The pulsatile fraction (BFP) of the BF was calculated by: BFP = BF-[(Doph/2)2 x 3.14 x VMdia]. Twenty eyes of 13 neurological patients were examined (mean age 58.6 +/- 15.3 years). The inner diameter of the OA was on average 1.14 +/- 0.26 mm (min. 0.52, max. 1.88). The mean blood velocity VMmean was on average 10.38 +/- 4.16 cm/s (min. 6.35, max. 21.8).(ABSTRACT TRUNCATED AT 250 WORDS)