Importance Understanding of intraocular pressure (IOP) as a continuous risk factor for glaucoma has evolved over time, and IOP reduction is widely acknowledged as the mainstay of treatment. However, the impact of specific IOP levels on clinical decision-making remains an underexplored topic. Objective To assess how IOP levels influence the decision to initiate or escalate glaucoma therapy in clinical practice. Design, Setting, and Participants In this retrospective, multicenter cohort study, the Sight Outcomes Research Collaborative (SOURCE) ophthalmology data repository was used to identify clinic encounters between October 2009 and January 2022 for patients with glaucoma with IOPs ranging from 12 mm Hg to 25 mm Hg. Data analysis was performed from July 2024 to September 2025. Main Outcomes and Measures The primary outcome was whether IOP-lowering therapy was initiated or escalated after each clinic encounter, defined as a new prescription for IOP-lowering medication within 1 week of the encounter, laser treatment within 4 weeks, or glaucoma surgery within 8 weeks. The rate of treatment initiation at different IOP levels was measured, and then mixed-effects logistic regression was used to model the odds of treatment initiation at specific indicator IOP levels. Results This analysis included 1 866 801 clinic encounters from 184 504 eyes of 94 232 unique patients across 7 sites in SOURCE. Mean (SD) patient age was 69.5 (10.8) years, and of the total clinic encounters, 1 084 827 (58.1%) included female patients. The rate of IOP-lowering treatment increased with higher IOP levels, with the largest acceleration in treatment rate at IOPs of 22 mm Hg or higher. With mixed-effects logistic regression modeling, an indicator IOP of 22 mm Hg had a greater effect on treatment initiation (odds ratio, 1.11; 95% CI, 1.08-1.14) compared with lower indicator IOPs. Conclusions and Relevance In this cohort study, while clinicians seem to generally use IOP as a continuous risk factor in their treatment patterns, with higher rates of glaucoma therapy at increasing IOP levels, these findings suggest that the historical IOP cutoff of 22 mm Hg may still influence clinician decision-making in glaucoma management. Improved clinical decision support may be useful to assist clinicians with using IOP as a continuous risk factor in their decision-making.