Fluorescein has a fluorescence lifetime of about 4 nanoseconds. In contrast, some dyes have lifetimes in measured in microseconds. When the lifetime is this long, they are arbitrarily considered to be phosphorescent dyes. There are several porphyrin-based phosphorescent dyes that can be used as oxygen probes. We have developed special versions of the Fluorotron that can be used with these dyes to measure oxygen in the eye.
Select References:
System for Ocular Oxygen Measurements. SBIR Grant R44EY015944.
Harvitt DM, Bonanno JA. Direct noninvasive measurement of tear oxygen tension beneath gas-permeable contact lenses in rabbits. Invest Ophthalmol Vis Sci 37(6):1026-36 (1996). PubMed
Bonanno JA, Stickel T, Nguyen T, Biehl T, Carter D, Benjamin WJ, Soni PS. Estimation of human corneal oxygen consumption by noninvasive measurement of tear oxygen tension while wearing hydrogel lenses. Invest Ophthalmol Vis Sci 43(2):371-6 (2002). PubMed
McLaren JW, Dinslage S, Dillon JP, Roberts JE, Brubaker RF. Measuring oxygen tension in the anterior chamber of rabbits. Invest Ophthalmol Vis Sci 39(10):1899-909 (1998). Erratum in: Invest Ophthalmol Vis Sci 40(12):2779 (1999). PubMed