• The effects of 4% topical epinephrine bitartrate on regional ocular blood flow were studied in normal, "sham-operated," and aphakic eyes of rabbits. Anterior uveal blood flow decreased in all cases, but reductions in the ciliary processes were less pronounced in aphakic eyes than in sham-operated eyes. Doubling the dose (from 2 to 4 drops) abolished this difference in the ciliary processes, but the increased dose was accompanied by the emergence of a similar (although lesser) effect in the iris. The latter dose additionally decreased retinal blood flow in aphakic eyes compared with the sham-operated eyes. Lens extraction, thus, seems to remove a notable diffusion barrier to topical epinephrine, resulting in both attenuation of its anterior segment effects and in potentiation of a vasoconstrictive response in the posterior pole.
Morgan TR, Mirate DJ, Bowman K, Green K. Topical Epinephrine and Regional Ocular Blood Flow in Aphakic Eyes of Rabbits. Arch Ophthalmol. 1983;101(1):112-116. doi:10.1001/archopht.1983.01040010114021