Abstract
Objective
To determine whether the cell measuring function of a laser flare-cell photometer is accurate and reproducible, using an in vitro model.
Sample Population
Leukocytes from 8 clinically normal Beagles.
Procedure
Latex beads 11.9 and 6.4 μm in diameter were used to simulate canine WBC and RBC, respectively. Beads were diluted to known concentrations, placed in a model eye, and counted by use of the laser flare-cell photometer. A range of protein diluents from 0 to 2,000 mg/dl was used to suspend beads and simulate anterior uveitis, when cells and protein would be in the aqueous humor. A similar series of experiments were repeated, using leukocytes isolated from the blood of Beagles.
Results
The laser flare-cell photometer can count 6.4-μm beads reproducibly and linearly up to a total of 510 cells/mm3, and 11.9-μm beads up to 1,300 cells/mm3 over a protein range of 0 to 2,000 mg/dl. The instrument can also count canine leukocytes reproducibly and linearly up to 1,300 cells/mm3 over that protein range.
Conclusions and Clinical Relevance
Cell and bead sizes and concentrations and protein concentrations were chosen to mimic the range observed in dogs with uveitis. Because the laser flare-cell photometer accurately counted these cells in a range of protein concentrations in the model eye, it has the potential for use in noninvasive quantitative evaluation and monitoring of uveitis in dogs. (Am J Vet Res 1998;59:1221–1226)
