Hydrogels for sustained delivery of biologics to the back of the eye

•Hydrogels provide a flexible platform for design of ocular delivery systems.•Intraocular injection of hydrogels can be accomplished via several strategies.•Achieving long-term release of biologics remains a major hurdle.•Ocular tolerability and CMC challenges must be addressed for clinical success. Hydrogels are water-laden polymer networks that have been used for myriad biological applications. By controlling the chemistry through which a hydrogel is constructed, a wide range of chemical and physical properties can be accessed, making them an attractive class of biomaterials. In this review, we cover the application of hydrogels for sustained delivery of biologics to the back of the eye. In adapting hydrogels to this purpose, success is dependent on careful consideration of material properties, route of administration, means of injection, and control of drug efflux, all of which are addressed. We also provide a perspective on clinical and chemistry, manufacturing and controls (CMC) considerations that are integral to the development of an ocular hydrogel delivery system. Hydrogels providing sustained delivery of biologics to the back of the eye can make a significant impact in the treatment of many ocular diseases. This article reviews the properties, administration approaches, and development challenges for an ocular hydrogel delivery system.