Influence of the Viscosity and the Surface Tension of Ophthalmic Vehicles on the Retention of a Tracer in the Precorneal Area of Human Eyes

Abstract

The influence of the viscosity and the surface active characteristics of dextran and polyvinylalcohol (PVA) solutions on the retention of fluorescein in the precorneal area of human eyes is investigated. A non-invasive method using a slit lamp fluorophotometer is employed. The tear elimination coefficient and the AUC value of the recorded fluorescence decay curve are calculated.The addition of dextran and polyvinylalcohol (PVA) to an iso-osmotic buffer solution retards the precorneal loss of fluorescein. The instillation of a 4.2% PVA solution, however, causes discomfort, inducing in some cases rapid blinking and elimination of the tracer.