Intravitreal Systems For Targeted Drug Delivery To The Posterior Eye Segment: A Systematic Review

Background — Intravitreal implants solve a number of serious problems arising in diseases of the posterior segment of the eyeball. Unlike intravitreal injections, the implant provides a prolonged release of a pharmaceutical drug over time. The review presents the characteristics of existing systems for intravitreal drug delivery: nanosystems, non-biodegradable and biodegradable implants. The review also highlights the main advantages and disadvantages of various implants. Based on the conducted literature review, the following conclusion is formulated: the most promising means of targeted drug delivery of drugs to the posterior segment of the eyeball are biodegradable implants. However, currently existing biodegradable implants do not provide entirely controlled release of the drug (uncontrollable extraction episodes occur at times), which constitutes a serious issue requiring improvement. Objective — to summarize the published data on existing systems for the targeted drug delivery into the vitreous chamber, identifying their major advantages and disadvantages. Material and Methods — Information was searched in such databases as PubMed, Google Scholar and ClinicalTrials.gov, using the keywords in both Russian and English languages: intravitreal implants, intraocular implants, biodegradable implants, non-biodegradable implants, nanosystems, nanoparticles, liposomes, targeted drug delivery, posterior segment of the eye, etc.