OBJECTIVES: Glaucoma is the second leading cause of bilateral blindness worldwide. Early detection and treatment can prevent the occurrence of blindness. The objective of this study is to determine the most cost-effective case-finding strategy to detect and treat ocular hypertension (OH) and primary open-angle glaucoma (POAG) by the ophthalmologist to prevent blindness. METHODS: An elevated intraocular pressure (IOP) defines OH and is a major risk factor for POAG. IOP is assessed by tonometry. Three case-finding strategies, which differ with respect to the group of patients receiving tonometry, are analyzed and compared using a Markov cost-effectiveness model. All patients undergo ophthalmoscopy to detect a glaucomatous optic nerve, but tonometry is routinely performed to: 1) all newly visiting patients; 2) high-risk patients only; or 3) no one. The population characteristics are based on the literature and on data gathered from the charts of 1000 new patients visiting an ophthalmic practice. Transition probabilities are taken from the literature. The (direct) costs of diagnosis and treatment represent those for The Netherlands. The time-horizon of the model is 20 years. An annual discount rate of 4% is used. RESULTS: Strategy three is cheapest but also yields most blindness. For strategy one, the computed extra costs to prevent one person from blindness amount to 7800€. For strategy two this is 19,500€. The marginal C/E ratio for strategy one is 1670€ per year of vision saved; for strategy two this is 4250€. These outcomes disregard extra costs due to blindness, estimated to exceed at least 5000€ per year of blindness. Strategy one is computed to become cost saving when such costs exceed 1700€. Extensive sensitivity analyses show that these results are robust. CONCLUSION: It is cost-effective to routinely perform tonometry to all new ophthalmic patients to prevent blindness due to glaucoma.