Precorneal drainage of polyvinyl alcohol solutions in the rabbit assessed by gamma scintigraphy

A method for monitoring the ocular distribution of solutions for ophthalmic use was developed using the technique of gamma scintigraphy. This method was used to monitor the effects of polyvinyl alcohol on the precorneal drainage of [99mTc]pertechnetate in the rabbit. The rate of drainage of solutions decreased on addition of PVA and precorneal residence of the marker was significantly prolonged, compared with saline controls, at a PVA concentration of 5% W/V. Increases in the activity in the inner canthal region mirrored the decrease in corneal counts. The method has a more general application for the study of ophthalmic formulations and devices in larger mammals and in man.