- Eye drops to lower intraocular pressure (IOP) remain the principal therapy for glaucoma. The path from the writing of a prescription of IOP-lowering drops to optimal lowering of IOP and preventing the development or worsening of glaucoma has many steps. One critical step is to maximize the amount of drug in the eye drop that reaches the target tissue in the eye once the eye drop is on the ocular surface. The literature supports the conclusion that eyelid closure (EC) and/or nasolacrimal occlusion (NLO) can increase the effect on IOP, decrease the frequency of dosing, and decrease blood levels. They do so by increasing the contact time of the applied drug with the ocular surface, and by decreasing the amount of drug that passes through the nasolacrimal duct and into the nasopharynx.