Safety and toxicity of nanomaterials for ocular drug delivery applications

Multifunctional nanomaterials are rapidly emerging for ophthalmic delivery of therapeutics to facilitate safe and effective targeting with improved patient compliance. Because of their extremely high area to volume ratio, nanomaterials often have physicochemical properties that are different from those of their larger counterparts. There exists a complex relationship between the physicochemical properties (composition, size, shape, charge, roughness, and porosity) of the nanomaterials and their interaction with the biological system. The eye is a very sensitive accessible organ and is subjected to intended and unintended exposure to nanomaterials. Currently, various ophthalmic formulations are available in the market, while some are underway in preclinical and clinical phases. However, the data on safety, efficacy, and toxicology of these advanced nanomaterials for ocular drug delivery are sparse. Focus of the present review is to provide a comprehensive report on the safety, biocompatibility and toxicities of nanomaterials in the eye.