Recent developments in nanotechnology to overcome the challenges in topical drug delivery to the anterior and posterior segments of the eye: review article

Eyes and the vision system allow the human being to receive information from the environment to the extent that 90% of the man’s information is acquired through observation، thus health and correct function of this organ have always been important. Diseases threatening vision such as Acute Macular Degeneration and Diabetic Retinopathy deprive millions of people of seeing every year while access to proper cures can prevent many ocular damages. Despite scientific progress in the medical fields over the recent decades there still exist many challenges in the field of ophthalmology and ocular diseases. As for ocular treatments، major challenges stem from pharmaceutical weaknesses، in other words in spite of access to the suitable drugs for ocular complications we have not yet succeeded to achieve an appropriate method to apply these drugs. By appropriate application of drugs we may deliver the active pharmaceutical ingredient to the target organ with the least side-effect، the most benefit and the highest level of patient compliance. Incapability of effective delivery of drug to the eye arises from the special physiology and anatomy of this organ. The static barriers such as Blood-Aqueous and Blood-Retinal and dynamic barriers such as conjunctival blood circulation and lymphatic clearance will reduce the bioavailability of ocular drugs. Overcoming the above-mentioned weaknesses requires a complete knowledge of the eye characteristics as well as acquaintance with novel drug delivery system. When speaking of drug delivery system (DDS) it means employing a two-part structure consist of active pharmaceutical ingredient (API) and carrier that in fact characteristics of formulated DDS will determine by the carrier. We may hope that by applying and designing modern pharmaceutical systems that mainly take advantage of nanoparticles we would be able to overcome many challenges of ocular drug delivery. The present study is aimed at reviewing the eye structure، challenges faced by ocular drug delivery، familiarity with nanotechnology and approaches of this science in the area of ophthalmology as well as mechanisms of designing a local system for effective drug delivery to the eye tissue.