Ocular Drug Delivery Systems for Treatment of Glaucoma

Glaucoma is a common eye disease that can cause irreversible blindness if left undiagnosed and untreated. Glaucoma is a prevalent neurodegenerative disorder of the eye. Glaucoma can be roughly divided into two main categories "open angle" and "closed angle" (or "angle closure") glaucoma. Every available treatment to prevent progressive glaucoma involves a certain amount of risk and financial expense. Conventional first-line treatment of glaucoma usually begins with the use of a topical selective or nonselective β-blockers or topical prostaglandin analogs. Second-line drugs of choice include α-agonists and topical carbonic anhydrase inhibitors. Parasympathomimetic agents, most commonly pilocarpine, are considered third-line treatment options. For patients who do not respond to antiglaucoma medications, laser trabeculoplasty and incisional surgery are further methods that can be used to lower intraocular pressure. Ocular drug delivery is hampered by the barriers protecting the eye. The bioavailability of the active drug substance is often the major hurdle to overcome. Conventional ocular dosage form, including eye drops, is no longer sufficient to combat ocular diseases. This article reviews the better understanding about glaucoma disease like prevention and diagnosis and explores various approaches like niosomes, liposomes, hydrogels, nanoparticles, nanosuspensions, microparticles, microemulsions, prodrugs and ocular inserts to improve the ocular bioavailability of drug and provide continuous and controlled release of the drug to the anterior and posterior chamber of the eye. In near future, a great deal of attention will be paid to develop a suitable and effective treatment for the vision threatening disorders like glaucoma.