Stratification of Tear Components During Tear Microdesiccation on Vertical Glass Surfaces: A Novel Approach in Tear Fluid Assessment

Abstract

Purpose:Tear desiccation on a horizontal glass surface followed by low-resolution light microscopy has been used as an expeditious diagnostic aid to evaluate patients suspected of dry eye. The presence of fern-like crystalloids in the dry specimen is the only feature taken into consideration. We demonstrate that different morphological domains of tear microdesiccates can be separated based on distinctive physicochemical properties.Methods:Healthy subjects (Ocular Surface Disease Index questionnaire, laboratory tests, and slit-lamp examination) and 74 young adults from a random student population were recruited as volunteer tear donors. Single tear samples were taken from individual eyes (n = 154) using absorbing polyurethane minisponges. From each sample, aliquots were allowed to desiccate simultaneously on microscope slides positioned either horizontally or vertically followed by comparative dark-field microscopy.Results:Vertical desiccation of each tear sample resulted in highly reproducible top-to-bottom stratification. Particular layers in any vertical microdesiccate represented morphological domains of the corresponding horizontal microdesiccate. Major fern-like crystalloids located at the center of Rolando type I horizontal microdesiccates became concentrated in a prominent layer at the bottom of vertical microdesiccates. Often, these fern-like crystalloids were more vigorous than those of the horizontal counterpart. A number of tear samples from the random population showed no ability to form fern-like crystalloids either by vertical or horizontal microdesiccation. Other prominent layers in vertical microdesiccates represented less noticeable circularly distributed morphological domains of the corresponding horizontal specimens.Conclusions:Microdesiccation of tear fluid on a vertical glass surface causes top-to-bottom stratification of diverse tear components. A more comprehensive expeditious tear assessment is feasible.