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A Novel Method for Determination of Surface Tension in Therapeutics of Tear-film Substitutes
1Weingärtner W. E., 1Spraul C. W., 1Buchwald H.-J., 2Wolf T., 1Lang G. K., 3Weber L. W.,
1Universität Ulm, Augenklinik und Poliklinik (Ulm)
2Universität Ulm, Institut für Arbeits-, Sozial- und Umweltmedizin (Ulm)
3Universität Ulm, Institut für Arbeits-,Sozial- und Umweltmedizin (Ulm)
Purpose: Each of the three tear film layers demonstrate a specific surface tension. The quality of these tear film layers may decrease with age and with associated ocular surface disorders. So far many different substances (liquids, gels and lotions) have been developed in order to improve the natural tear film or substitute it. Up to now the current available therapeutics are chosen and selected according to their individual success. There are only few methods available for systematic optimization of this process.
Method: Utilizing a new method for dynamic surface tension measurement, the micro bubble surface tensiometer, the surface characteristics of different tear therapeutics. For this purpose dilution series of different therapeutics with water and isotonic NaCl solutions were performed. According to their influence on the high association status of water or physiological salt solutions a dose dependant decay of the surface tension is achievable. Initially, the available therapeutics with their galenic composition are examined in dilution series. For individual aqueous solutions of tear therapeutics the surface tension was measured in dilutions. The results were correlated with the ingredients in each galenic composition. Additionally, specific dilution curves were obtained for gelious preparations.
Results: This novel method is a highly reliable tool for surface tension measurement. We were able to measure the surface tension of tear film therapeutics in vitro as well as the dynamic changes in vivo.
Conclusions: With a new and sensitive surface tension measurement device we were able to characterize the surface quality of tear film therapeutics. With a new patch system, which will be used for dosing and measuring of tear film therapeutics, the application of eye drops can be monitored in vivo in a dynamic way. The herein presented surface tension values are used as reference data.