Orthogonal polarization spectral imaging of conjunctival microcirculation.

Purpose: Orthogonal polarization spectral (OPS) imaging is an optical imaging technique that uses a handheld microscope and green polarized light to visualize the red blood cells in the microcirculation of organ surfaces. The purpose of this study was to evaluate whether OPS imaging can be used for the functional and morphological evaluation of microcirculation in the conjunctiva.

Methods: To accomplish the aforementioned purpose, 21 eyes of 21 volunteer patients were examined. OPS images of the vasculature of the inferior conjunctiva and the nasal part of the bulbar conjunctiva were taken from each eye. The images were subsequently analyzed using a computer, and the following parameters were assessed: red blood cell velocity, blood vessel diameter, and functional capillary density. In addition, distinct qualitative aspects of the conjunctival microvasculature were characterized.

Results: OPS imaging facilitated both the observation of red blood cells that were flowing through conjunctival vessels on a white background, and the measurement of other quantitative and qualitative microvascular parameters. Significant differences between several measures of the inferior and nasal bulbar conjunctival microcirculations were found, including differences in the configurations of the vessel segments, the number of vessel segments, the number of bifurcations, the mean diffusion distance, and the functional capillary density.

Conclusions: OPS imaging can be used to measure the diameters of microvessels, functional capillary density, and other parameters. Significant differences between the microcirculations of the inferior conjunctiva and the nasal bulbar conjunctiva were found, which indicates the necessity of using a standardized approach to examine the conjunctival vasculature. OPS imaging is suitable for both the functional and morphological evaluation of the conjunctival microcirculation.