OBJECTIVES: Glaucoma causes an atrophy of the optic nerve with increased intraocular pressure (IOP), which can lead to blindness. When topical treatment fails to lower IOP adequately, the patient may add or change medications or have surgery/laser treatment. Prostaglandin therapy is recommended as initial therapy. The purpose of this study was to compare medication adherence, persistence, and post-index patterns between latanoprost, bimatoprost, and travoprost as initial therapies for glaucoma/ocular hypertension.  METHODS: The study cohort consisted of Humana commercial and Medicare Advantage plan members over 40 identified between 2007 and 2010, as newly diagnosed with glaucoma, ocular hypertension, or suspected glaucoma (ICD-9 code; 365.xx, 377.14) with at least one paid prescription claim for a topical ocular hypotensive medication. At least 365 days of continuous enrollment after the date of the first latanoprost, travoprost, or bimatoprost fill was required. The medication possession ratio (MPR) was used to measure medication adherence. Persistence was defined as duration of continuous treatment with the initially prescribed glaucoma medication without a 60-day gap. RESULTS: Patients who had latanoprost, travoprost, and bimatoprost as initial therapy accounted for 50.3%, 30.3%, and 19.4%, of patients respectively.  Latanoprost users had significantly higher average MPR than travoprost and bimatoprost users (61.4% vs. 47.4% and 58.2%, p<.0001). Latanoprost users had significantly longer persistence than travoprost and bimatoprost (199 vs. 145 and 171 days, p<.0001). About 30% in each group had changes in therapy.  Of those changing therapy, most switched to another medication (47.4%, 56.8%, and 47.0%), followed by adding a medication (42.0%, 33.3%, and 40.5%), and surgery/laser treatment (11.6%, 10.0%, and 12.5%) for latanoprost, travoprost, and bimatoprost users (respectively).  CONCLUSIONS: The study suggests that latanoprost users showed higher adherence and longer persistence compared to travoprost and bimatoprost users, and switching was more common than addition of medication therapy or surgery for all cohorts.