Effect of Myocilin Genetic Variants on Intraocular Pressure and Pressure Variation in Sitting and Supine Positions

Inclusion Criteria: * Early OAG, as determined by a comprehensive ophthalmic examination * Greater than or equal to 18 years of age * Either gender * Any race * Both eyes meet eligibility criteria * Cup to disc ratio less than 0.8 determined by fundoscopy and confirmed by disc photos * Visual field parameters in the study eye: Pattern Standard Deviation (PSD) greater than 1.0 dB but less than 6.0 dB * Ability to cooperate for an outpatient study involving at least five visits over a four month study period * Ability to comply with Cosopt treatment regimen Exclusion Criteria: * Less than or equal to 18 years old * Refusal to be genotyped or sign Informed Consent for Protocol 1991-144 * Pregnant or lactating women * Medical conditions of severe pulmonary compromise with asthma or emphysema or cardiac contraindications to beta-blockers * Ocular disease of chronic angle-closure glaucoma, iridocorneal endothelial disease, posterior polymorphous corneal dystrophy, epithelial downgrowth, uveitic glaucoma, or neovascular glaucoma * Ocular surgery for glaucoma, including trabeculectomy, other glaucoma filtration surgery, glaucoma drainage implant, or laser cyclophotocoagulation * Current use of systemic steroids or chemotherapeutic agents that non-selectively inhibit dividing cells * Proliferative diabetic retinopathy, history of panretinal photocoagulation treatment, diabetic macular edema, or history of macular grid laser treatment * History of changing treatment involving the us…