Quantitative tear meniscus cytology versus quantitative conjunctival fluid cytology

A technique for quantitative cytology of tear fluid collected by a micropipette from the tear meniscus is presented. This technique has been compared with that using the standardized Norn-pipette collecting fluid from the lateral part of the inferior fornix. The two methods show the same magnitude of sensitivity and specificity, the same coefficient of variation, as regards neutrophilic leucocytes and erythrocytes (200 samples). The normal tear meniscus contains less than 40 leucocytes or erythrocytes per microliter. The tear cell concentration is about 200 times lower in the meniscus than in the fornix inferior in normal eyes. This observation supports the compartment-theory of a rapid flow in the tear meniscus and a slow flow with insignificant admixture in the conjunctival fluid in the fornices. The tear meniscus cytology is of use in association with testing of other parameters in the tears, for instance. The conjunctival fluid cytology is quicker and more convenient for the patient. In addition, it is necessary in connection with observation for pathological epithelial desquamation, because the tear meniscus cytology brings about an artificial increase of the epithelial cell concentration.