[The use of sustained-release preparations for eye-platelet diagnosis for noninvasive determination of leukocyte migration in the eye].

An in vivo method for measuring leukocyte migration in man involves the insertion of membrane filter platelets into the lower conjunctival sac. Before insertion, the filter platelets were soaked in solutions of chemotactic test substances and dried. The chemotactic gradient formed by a dissolving test substance stimulates leukocytes from the conjunctival mucosa to immigrate into a filter platelet. The number and the distribution of immigrant cells within the filter platelet yield information on pathological processes. To obtain reliable results, the chemotactic substance used has to show a defined solubility inherent in only a minority of all substances in question. In order to stabilize liberation, the chemotactic test substance is introduced together with a hydrogel-forming substance into a filter platelet. Among a series of tested hydrogel-forming substances, the Guar derivative Meyprogat 90 proved to have the best stabilizing capacity. For an exact measurement of liberation, a new in vitro model was developed that simulates the conditions of drug liberation within the conjunctival sac. In vitro as well as in vivo tests with this type of filter platelets proved their qualification for human medicine.