Does prior instillation of a topical anesthetic enhance the effect of tropicamide?

Preinstillation of a topical anesthetic has been reported to increase the effect of subsequently applied mydriatics. We examined the effect of instilling 1 drop of proparacaine hydrochloride (0.5%) before applying 1 drop of tropicamide (1%). The results show that preanesthesia prolongs the mydriatic and the cycloplegic effects of tropicamide in eyes with either lightly or more heavily pigmented irides.