Thymoxamine, an α-adrenergic blocking agent, applied topically was found to be effective in reversing an attack of angle-closure glaucoma, uncomplicated by peripheral anterior synechiae.
The rationale for using thymoxamine is based on a mathematical model explaining the mechanics of pupillary block.
The miosis produced by thymoxamine decreases the posterior vector of the force due to contraction of the sphincter, which favors pupillary block, and at the same time eliminates, by inhibition, the posterior vector of the force due to contraction of the dilator.
Halasa AH, Rutkowski PC. Thymoxamine Therapy for Angle-Closure Glaucoma. Arch Ophthalmol. 1973;90(3):177-179. doi:10.1001/archopht.1973.01000050179001