Intraocular drug delivery methods: Conventional versus modern approaches

AbstractIntravitreal injection (IVI) belongs to a standard and most used drug delivery technique for the treatment of exudative age‐related macular degeneration (AMD) and other ocular diseases associated with increase of VEGF concentration in the vitreous cavity and retinal layers. Moreover, this technique is used to inject antibiotics, steroids, antiviral, antifungal and cytostatic agents during the treatment of eye infection and eye injury. The risk of serious vision‐threatening complications after IVI, including aseptic and septic intraocular inflammation, is very low. However, the number of patients who require the IVI grows together with the absolute number of serious injection‐associated complications. Regarding the rate of endophthalmitis, various possible contamination mechanisms have been considered, including contamination of the surface of the eye, contamination of the needles or therapeutic substances, etc. Nevertheless, an accurate mechanism of these contaminations as well as the ways to prevent them remains unclear. It was suggested, that one of the possible causes of the post‐IVI inflammation is the use of hypodermic needles with the sharp tip, which cuts out potentially contaminated cellular material and brings it inside the eye together with the drug. Modern studies are focused on the enhancement of the safety of the IVI technique by developing less traumatic injection needles. Drug companies are developing the new drugs, which action is more prolonged in order to reduce the number of required injections. Additionally, the new alternative drug delivery systems have been proposed and already tested in the clinical condition. Development of novel intraocular drug delivery techniques with their implication into the everyday practice will improve the safety profile of the treatment methods.