The purpose of this study was to investigate, in cats, the effects of topic
al epinephrine on aqueous humor dynamics as measured by the non-invasive me
thod of fluorophotometry and by other methods. Measurements were carried ou
t on 12 cats before and after one week of twice daily treatment with 2 % ep
inephrine hydrochloride to one eye. Aqueous flow and outflow facility were
determined using fluorophotometry. Uveoscleral outflow was calculated from
these results and was evaluated with anterior chamber perfusion of FITC-dex
tran. Outflow facility also was measured by tonography. Epinephrine-treated
eyes, compared with their baseline values, showed a 31 % reduction in intr
aocular pressure (P < 0.001), a 23 % reduction in aqueous flow (P < 0.05),
a 60 % increase in fluorophotometric outflow facility (P < 0.05), and a 43
% increase in tonographic outflow facility (P < 0.05). Treated eyes, compar
ed with contralateral control eyes, showed a 27 % reduction in IOP (P < 0.0
05), a 25 % reduction in aqueous flow (P < 0.005), a 38 % increase in fluor
ophotometric outflow facility (P < 0.05), and a 34 % increase in tonographi
c outflow facility. When evaluated by both fluorophotometry and FITC-dextra
n tracer methods, epinephrine had no significant effect on uveoscleral outf
low. It was concluded that, in cats treated with topical epinephrine twice
daily for a week, a reduction in intraocular pressure is induced by an incr
ease in outflow facility and decrease in aqueous flow. (C) 1999 Academic Pr
ess.