|
In-vivo Measurement
of Red Blood Cell Velocities using the Scanning Laser Ophthalmoscope
Wajer, Stephen1
and Lutty, Gerard2
The Johns Hopkins University Applied Physics Laboratory1
The Wilmer Ophthalmological Institute, The Johns Hopkins Medical Institutions2
Abstract-
In vivo measurement of red blood cell (RBCs) velocities in the retinal
and choroidal vasculatures of the eye were made using a Rodenstock scanning
laser ophthalmoscope (SLO). This was accomplished by dynamically viewing
FITC-labeled RBCs in anesthetized rats with the SLO and their circulation
recorded directly to digital format using a Hi8 camcorder. Velocities
of RBCs from rats, normal humans, and human sickle cell donors were
measured from video frame sequences in retinal arteries, capillaries,
and veins and in choroidal capillaries of rats. Rat and normal human
RBCs differ slightly in size; however, their velocities were similar
in the retinal arteries and capillaries. Neither of these cell types
was retained in the vasculatures during this study. Velocities of RBCs
from sickle cell patients (sRBCs) were slower in arteries and in capillaries,
compared to rat and normal human RBCs. The velocities in choroidal capillaries
were much slower for all types of RBCs compared to velocities in retinal
capillaries. Large numbers of sRBCs were retained in choroidal capillaries
for extended periods at preferred sites. SLO imaging of FITC-labeled
RBCs provided a reliable method to evaluate normal and abnormal hemodynamics
and should be useful in evaluating effects of pharmacological agents
on vaso-occlusive processes and pathologic RBC hemodynamics.
Keywords: in-vivo,
noninvasive, red blood cells (RBCs), ophthalmoscope (SLO)
|
