Abstract
Purpose::
Spectral analysis of the Doppler signal recorded in the central vein and artery of the retina with color-coded pulsed Doppler ultrasound imaging (CPDU) were compared in subjects suffering from CRVO to normal subjects.
Methods::
Twenty normal subjects ( 25 to 50 years old), and six patients ( 40 to 60 years old) suffering from CRVO were explored. Peak systolic (PSBFVca) - diastolic (EDBFVca) and time-average mean blood flow velocities (MeanBFVca) in the central artery of the retina, maximum (MaxBFVcv), minimum (MinBFVcv) and time-average mean blood flow velocities in the central vein downstream retina (MeanBFVcv) were measured using a (CPDU).
Results::
In normal subjects, in the central artery, PSBFVca was 12.9 ±3.4 cm.s-1, EDBFVca 4.8 ±1.7 cm.s-1, MeanBFVca was 4.1± 1.1 cm.s-1, in the central vein, MaxBFVcv was 5.1 ±1.1 cm.s-1, MinBFVcv 3.2 ±0.7 cm.s-1, and MeanBFVcv 2.4 ± 05 cm.s-1. For eyes suffering from CRVO, PSBFVca was 8.9 ±1.3 cm.s-1, EDBFVca 3.0 ±0.7 cm.s-1, MeanBFVca 3.2± 0.5 cm.s-1, MaxBFVcv 4.4 ±1.3 cm.s-1, MinBFVcv 2.9 ±0.8 cm.s-1, and MeanBFVcv 2.1 ± 05 cm.s-1. For healthy eyes, PSBFVca was 13.7 ±3.3 cm.s-1, EDBFVca was 4.9 ±1.3 cm.s-1, MeanBFVca was 4.4± 1.2 cm.s-1, MaxBFVcv 5.9 ±1.3 cm.s-1, MinBFVcv 3.8 ±0.8 cm.s-1 and MeanBFVcv 2.7 ± 05 cm.s-1.
Conclusions::
There is no significant difference between velocities measured in eyes in normal subjects and in the healthy eyes of subjects suffering from CRVO. For the eyes suffering from CRVO, arterial and venous blood flow velocities were significantly decreased compared to those measured on the healthy eyes in subject with CRVO and those of normal subjects. Thus, CRVO involved an increase in vascular resistances in the vascular supply of retina, and involved upstream a recognizable decrease in arterial blood flow velocities and in blood flow rate. This could be explained by the vascular anatomy in which arterial and venous blood flow rates must be equal. Decrease in blood flow velocities do not seem to depend from the time between the occlusion and the ultrasound study. This could accredit the hypothesis of a very rapid opening of collateral vessels i.e. capillaries located in the papilla which are normally non functional proceeding from chorionic vasculature to supply retina.
Keywords: blood supply • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • ischemia