Ophthalmically therapeutic materials, such as liquid-containing compositions and polymeric drug delivery systems, include a therapeutic component which includes an alpha 2 adrenergic receptor agonist that is cleared from the anterior segment of an individual's eye to which the material is administered. The alpha 2 adrenergic receptor agonist may have a vitreal half-life greater than about three hours. The present materials are effective in treating an ocular condition(s) that affect the anterior segment of an eye, or the anterior and posterior segment of the eye. The materials are suitable for intravitreal or periocular administration and can provide prolonged drug delivery and therapeutic benefits to patients to which the materials have been administered. The alpha 2 adrenergic receptor agonists can be provided in liquid-containing formulations and/or bioerodible and/or non-bioerodible polymeric implants and microparticles. Methods of making and using the present materials are also described.