Hydrogels in ophthalmic drug delivery system - A mini review

The frequent demand for effective eye therapies is acting as driving force for the development of injectable hydrogels as new medical devices for controlled delivery and filling purposes. The delicate structure and the protective physiological process of our eye exert a defense system against ophthalmic delivery of drug, which ultimately led to poor precorneal drug loss, resulting in poor ocular bioavailability. To improve ophthalmic preparation’s bioavailability, there are valuable efforts directed toward newer drug delivery systems for ophthalmic administration. As we know that other conventional delivery system gives poor therapeutic response and bioavailability because tears have high fluid turnover and dynamics due to which rapid elimination of drug from the eye takes place. In situ polymeric formulations are drug delivery systems that are in sol form before administration in the body, but on administration, they undergo gelation in situ, to form a gel. The formation of gels depends on factors such as temperature modulation, pH change, presence of ions, and ultraviolet irradiation, from which the drug gets released in a sustained and controlled manner. This article introduces the properties and mechanisms of injectable hydrogels and summarizes their versatile application in the treatment of ophthalmic diseases, including age-related macular degeneration, cataracts, diabetic retinopathy, glaucoma, and intraocular cancers.