Nanomedicine-Based Approaches for Treatment of Ocular Diseases

Nanomedicine is a new frontier in the treatment of eye diseases with disruptive novelty, from overcoming unique anatomical and physiological barriers that historically impeded drug delivery to the eye. Most ocular diseases, such as glaucoma, AMD, diabetic retinopathy, and uveitis, pose serious challenges to treatment as a result of their complex anatomy and protective mechanisms limiting drug penetration and retention. These old and conventional forms, such as eye drops and ointments, cannot achieve the desired therapeutic concentrations at the target site; hence, efficacy is likely to be compromised and patient compliance will also be poor. Recent nanomedicine-based drug delivery strategies are discussed and applied to ocular drug delivery. Due to their tiny size and large surface area, nanoparticles can carry a variety of therapeutic drugs. Therefore, the solubility and stability of these drugs are much improved. This nanoparticle can serve with controlled and sustained release that enhances bioavailability, thus exhibiting better treatment outcomes. Among these are liposomes, dendrimers, and polymeric nanoparticles; their type shows promise in preclinical as well as clinical studies regarding the treatment of ocular conditions. These liposomes constitute an effective entity because of the biocompatibility of lipid bilayers for the treatment of diseases such as dry eye syndrome and corneal infections, which would allow a mechanism for targeted delivery and sustained release of the drug. Dendrimers, having a highly branched and functionalized surface, do offer an opportunity to control drug targeting and release in diseases such as AMD and glaucoma. The polymeric nanoparticles bearing biodegradable polymers release the drug at a sustained rate with improved stability and have a better prognosis for chronic diseases such as uveitis and diabetic retinopathy. Some of the innovations in nanomedicine encompass drug-eluting contact lenses, sustained-release implants, and gene therapy. The drug-eluting contact lens would serve the purpose of correcting vision by staying in touch with the ocular surface for an even longer period and delivering drugs simultaneously. Some of the sustained-release implants, such as Ozurdex and Retisert, possess the ability to administer long-term drug delivery in chronic conditions with a reduced need for administration throughout the treatment phase. Gene and RNA-based treatments are also gaining ground as potential therapy candidates for the eyes. The concept of gene therapy is that corrective genes are directed delivered into an eye to correct defects in genes causing disease. Others involve interfering with the message of disease-causing genes by using RNAi or introducing specific mRNA strands that introduce new gene expressions.