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Direct and noninvasive assessment of parafoveal capillary leukocyte velocity.

Martin JA, Roorda A

College of Optometry, University of Houston, Houston, Texas, USA.

PURPOSE: Alterations in leukocyte velocity have been implicated in many retinal disease processes. However, direct and objective assessment of leukocyte velocity in retinal capillaries has been limited by a reliance on invasive contrast dyes that allow leukocyte visualization only for a short time span. The recent application of adaptive optics in a scanning laser ophthalmoscope (AOSLO) has made long-term imaging of parafoveal leukocyte movement possible without contrast dyes. In this study, using the AOSLO, we demonstrate a new method to investigate retinal parafoveal capillary leukocyte velocity. DESIGN: Experimental study. PARTICIPANTS: Six normal healthy subjects ranging from 25 to 35 years of age with clear ocular media. METHODS: The parafoveal zone of the retina was imaged in all subjects using an AOSLO. MAIN OUTCOME MEASURES: Leukocyte velocity was determined in the parafoveal capillaries including the foveal avascular zone border. Leukocyte velocity was measured directly from movie segments in which the leukocytes were clearly visible. RESULTS: The mean parafoveal leukocyte velocity for 6 subjects was 1.37 mm/second, ranging from 0.77 to 2.10 mm/second. Leukocytes were not visible in all parafoveal capillaries. CONCLUSIONS: Parafoveal capillary leukocyte velocity can be directly and noninvasively measured without the use of contrast dyes using an AOSLO.

Published 5 December 2005 in Ophthalmology, 112(12): 2219-24.
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