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Article
December 1990

Time Course of Thymoxamine Reversal of Phenylephrine-Induced Mydriasis

Author Affiliations

From the W. K. Kellogg Eye Center, Department of Ophthalmology, University of Michigan, Ann Arbor (Drs Wright, Skuta, Rabbani, and Musch), and Beckman Vision Center, Department of Ophthalmology, University of California, San Francisco (Drs Drake, Chang, and Teikari).

Arch Ophthalmol. 1990;108(12):1729-1732. doi:10.1001/archopht.1990.01070140083034
Abstract

• 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≤.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<.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.

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