Time course of thymoxamine reversal of phenylephrine-induced mydriasis.
We conducted a randomized, double-masked, paired comparison of 0.1% thymoxamine vs placebo for the reversal of phenylephrine-induced mydriasis. Mydriasis was induced with 2.5% phenylephrine in each eye of 74 subjects (148 eyes). Each subject then received 0.1% thymoxamine in one eye and placebo in the other eye. Pupillary measurements were obtained at regular intervals during the ensuing 8 hours. At all intervals, a greater percentage of thymoxamine-treated eyes returned to baseline pupillary diameters compared with placebo-treated eyes (P less than or equal to .01). For subjects in whom both pupils returned to baseline, thymoxamine-treated eyes returned to baseline in a mean of 2.2 hours, vs 5.2 hours for placebo (P less than .0001). Among thymoxamine-treated eyes, those with light irides responded more rapidly than those with dark irides, returning to baseline in 1.6 vs 2.8 hours, respectively (P = .0046). After constriction to baseline pupillary diameter had been achieved, no patients experienced a rebound dilation.
Wright
M M
MM
W.K. Kellogg Eye Center, Department of Ophthalmology, University of Michigan, Ann Arbor 48105.
Skuta
G L
GL
Drake
M V
MV
Chang
L F
LF
Rabbani
R
R
Musch
D C
DC
Teikari
J
J
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007498:Iris / Q000502:physiology; D008297:Male; D008875:Middle Aged; D013948:Moxisylyte / Q000494:pharmacology*; D009184:Mydriatics / Q000494:pharmacology*; D010656:Phenylephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010858:Pigmentation; D011680:Pupil / Q000187:drug effects; D013997:Time Factors
D009184:Mydriatics; D010656:Phenylephrine; D013948:Moxisylyte