Several new topical agents have been introduced recently and it can be expected that the treatment of glaucoma will change, depending on how effectively these agents control intraocular pressure (IOP). IOP is considered the major risk factor in the development of glaucomatous damage. In order to estimate the impact of these new agents on the cost of treating glaucoma, a simulation model was created to estimate the cost of treating patients with a recent diagnosis of primary open-angle glaucoma or ocular hypertension in different countries. The Markov model is based on retrospective chart reviews in different countries and calculates only cost, not outcome. Results are presented for France and the United Kingdom, where current treatment appeared to be comparable. Average one-year costs per patient with current treatment were FF2,389 (US $389) and 380 pounds (US $627), respectively. Costs with the new treatments were lower than with current therapy.