An Update on Novel Drug Delivery Systems for the Management of Glaucoma

Glaucoma is recognized as a chronic optic neuropathy marked by progressive optic nerve degeneration, loss of retinal ganglion cells (RGCs, the neurons responsible for transmitting visual information from the eye to the brain), disruptions in optic disc blood supply, and changes in glial cell activation. It ranks as the second most prevalent cause of irreversible visual impairment worldwide and is a resultant of increased intraocular pressure (IOP). Addressing this condition proves complex due to the inherent hindrances posed by ocular barriers, which curtail the entry of drugs into the eye. Diverse carriers such as inorganic nanoparticles, polymeric nanocarriers, hydrogels, and contact lens-based systems with distinct physical and chemical attributes are being studied for drug delivery. They have shown enhanced ocular drug bioavailability through higher penetration across ocular tissues, prolonged retention in the precorneal space, sustained drug release, and targeted delivery to specific tissues. These ingenious delivery systems can be deployed through various administration routes-intravitreal or periocular injections or systemic administration-enabling the drugs to reach affected areas, aiding in the regeneration of compromised optical nerves. This review presents a comprehensive exploration of contemporary strides in ocular delivery formulations pertaining to glaucoma. This encompasses an examination of various nanocarrier typologies, delivery routes, in vitro and in vivo effectiveness, clinical applicability, and a forward-looking perspective into potential future developments.