Affiliations: Department of Medical Laboratories, School of Health Sciences, Technological Educational Institute of Larissa, Larissa, Greece | Ophthalmology Department, University of Thessaly, University Hospital of Larissa, Larissa, Greece | Technology of Informatics and Telecommunications Department, Technological Educational Institute of Larissa, Larissa, Greece
Note: [] Address for correspondence: Dr. Aristotle G. Koutsiaris, Department of Medical Laboratories, School of Health Sciences, Technological Educational Institute of Larissa, Larissa 41110, Greece. Fax: +30 2410 555378; E-mail: ariskout@otenet.gr.
Abstract: Understanding the mathematical relationships of volume blood flow and wall shear stress with respect to microvessel diameter is necessary for the study of vascular design. Here, for the first time, volume flow and wall shear stress were quantified from axial red blood cell velocity measurements in 104 conjunctival microvessels of 17 normal human volunteers. Measurements were taken with a slit lamp based imaging system from the post capillary side of the bulbar conjunctiva in microvessel diameters ranging from 4 to 24 micrometers. The variation of the velocity profile with diameter was taken into account by using a profile factor function. Volume flow ranged from 5 to 462 pl/s with a mean value of 102 pl/s and gave a second power law best fitting line (r=0.97) deviating significantly from the third power law relation with diameter. The estimated wall shear stress declined hyperbolically (r=0.93) from a maximum of 9.55 N/m2 at the smallest capillaries, down to a minimum of 0.28 N/m2 at the higher diameter post capillary venules. The mean wall shear stress value for all microvessels was 1.54 N/m2.
Keywords: Human microvessels, bulbar conjunctiva, diameter, slit lamp
Journal: Biorheology, vol. 44, no. 5-6, pp. 375-386, 2007
