Cycloplegic agents may cause elevation of intraocular pressure in certain eyes without angle closure. Significant pressure increments occur in treated and untreated open angle glaucoma patients but are rarely noted in normal patients. Roughly one third of miotic-treated patients with open angle glaucoma studied by the authors are cycloplegic responsive. In approximately 50% of these patients the response represents a competitive inhibition of the miotic by the cycloplegic. In the remainder, a direct effect on ciliary muscle is possible.
Harris LS, Galin MA. Cycloplegic Provocative TestingEffect of Miotic Therapy. Arch Ophthalmol. 1969;81(4):544-547. doi:10.1001/archopht.1969.00990010546014