Prostamide-containing intraocular implants that biodegrade in the eye and that are effective for reducing intraocular pressure in an eye for a sustained period. The implants generally contain a prostamide, such as bimatoprost, and at least three distinct biodegradable polymers selected from polylactide and poly(lactide-co-glycolide) polymers and are optimized for placement in and compatibility with the anterior chamber of the eye, particularly the anterior chamber angle. Methods for making and using the implants to reduce ocular hypertension and intraocular pressure in a patient are described.