Nanotherapeutics for diabetic retinopathy using metal nanocomposites

Diabetic retinopathy (DR) is a prime cause of blindness in type I and type II diabetes mellitus patients which may start showing significant symptoms after a decade of diagnosis of diabetes. Persistent hyperglycemia leads to elevated reactive oxygen species (ROS), exudation from the blood vessel, and disturbed microcirculation in the retina leading to ischemic vascular degeneration, pathologically termed diabetic retinopathy. To restore blood supply, vascular endothelial growth factors (VEGF) promote neovascularization. Fatedly, the development of new blood vessel generation in the retina causes retinal detachment resulting in blindness. Early intervention with timely diagnosis of retinal ischemia and angiogenesis in DR, blindness can be prevented. The major hurdle in the treatment of DR is poor or deranged vascularization making the blood-retina barrier (BRB) a challenge for drug delivery. Ocular barriers influence the efficiency of topically administered drugs for the treatment of the posterior segment of the eye. Recently, nanotechnology has been progressively useful in the prevention and treatment of DR, addressing many problems in traditional treatments. Nanoparticles (NPs) have high permeability across BRB and good biocompatibility. Hence, they can easily pass through biological barriers and increase the bioavailability of drugs. Drugs entrapped in NPs can increase the solubility and retention in the vitreous humor. They provide a controlled release and reduced drug degradation in the body which can be effective for nerve tissue regeneration. Among various NPs, metal nanoparticles (MNPs) look very propitious for the treatment of DR as they possess anti-angiogenic and anti-inflammatory properties. This chapter describes the role of MNPs in the therapeutic and theranostic approach for DR, focusing on ROS and neovascularization.