Influence of Alpha-Adrenoceptor Blockade with Thymoxamine on Changes in Pupil Diameter and Accommodation Produced by Tropicamide and Ephedrine

Summary

In a study in 12 healthy volunteers, local instillation of thymoxamine eye-drops (0.2 %) completely reversed the mydriasis produced by ephedrine (5 %) but not that produced by ephedrine (5%) together with tropicamide (0.5%). Small but significant changes in accommodation were found with ephedrine and reversed by thymoxamine, suggesting that they were mediated through alpha-adrenoceptor activity. The thymoxamine eyedrops were well tolerated.