Lacrimal microscintigraphy, in conjunction with a recently developed computer system, was used to evaluate the corneal contact time of three ophthalmic vehicles in 18 humans. The percentage of a radioactively labeled vehicle remaining over the cornea after 90 seconds was 2.9% ± 2.2% for saline, 4.3% ± 2.4% for polyvinyl alcohol, and 8.8% ±4.1% for hydroxypropyl methylcellulose.
Trueblood JH, Rossomondo RM, Carlton WH, Wilson LA. Corneal Contact Times of Ophthalmic VehiclesEvaluation by Microscintigraphy. Arch Ophthalmol. 1975;93(2):127-130. doi:10.1001/archopht.1975.01010020133008