In studies of new glaucoma medications the preferred study population includes ocular hypertensive subjects. These people have high IOP but no optic nerve damage and no glaucoma. They may be taking prescribed IOP lowering drugs for this condition or they may not. Those taking ocular drugs are asked to stop taking them. Since glaucoma drugs affect aqueous humor dynamics in different ways, it is essential that no residual medical effect remains from these drugs. A washout period is necessary to remove all topical ocular drug effects. A concern for patient safety exists when OHT patients are taken off of glaucoma medications, as IOP may rise during the washout period. In order to monitor IOP in these patients, a biweekly check of the IOP is made. If pressure rises above the ophthalmologist's preset "target pressure" at any point, then the patient is removed from the study and returned to his/her previous medical regimen.