Triamcinolone and intraocular sustained-release delivery systems in diabetic retinopathy

Diabetic retinopathy (DR) still represents one of the leading causes of vision loss worldwide. Since this condition affects the posterior segment of the eye, topical application of ophthalmic medicines is of limited benefit, considering that they seldom reach therapeutic levels in the affected tissues. Systemic medications can be insufficient due to the eye's immunoprivileged condition and existence of both inner and outer blood-retinal barriers, which place limitations on the potential role of this route of administration for retinal diseases. In this setting, intraocular therapies have emerged as novel and vital tools in the ophthalmologist's armamentarium against DR, allowing for maximization of drug efficacy and limited risk of systemic side effects. Intravitreal injections of triamcinolone acetonide have been widely used for treating DR particularly in the 21^st century. Other agents targeting molecules, such as anti-vascular endothelial growth factor, have also demonstrated a potential therapeutic role for treatment. Recent advances in ocular drug delivery methods have led to the development of intraocular implants, which help to provide prolonged treatment with controlled drug release. Moreover, they may add some potential advantages over traditional intraocular injections by delivering certain rates of drug directly to the site of action, amplifying the drug's half-life, contributing in the minimization of peak plasma levels of the drug, and avoiding the side effects associated with repeated intravitreal injections.