Place of intravitreal dexamethasone implant in the treatment armamentarium of diabetic macular edema

Abstract

Diabetic macular edema (DME) is a very important and well-known cause of visual loss in diabetics. Blood–retina barrier disruption and consequent intraretinal fluid accumulation may lead to retinal thickening at the posterior pole namely DME. Even though it is not clearly understood, current evidence suggests that chronic low-grade inflammation characterized with various cytokines has a major role in the occurrence of DME. Clinical trials are continuously shaping our treatment approaches for the eyes with DME. Today, vascular endothelial growth factor (VEGF) inhibitor and steroid administrations are the main alternatives in DME treatment. Dexamethasone (DEX) implant (Ozurdex^®; Allergan, Inc., Irvine, CA, United States) was approved by the United States Food & Drug Administration in 2014 for DME treatment. The implant is made up of a biodegradable solid copolymer that is broken down by releasing its active ingredient into the vitreous cavity over time. Biphasic release feature of this sustained-release drug delivery system ensures its efficacy for up to 6 mo with an acceptable and manageable safety profile. DEX implant provides a favorable anatomical and functional outcome in DME as shown in several randomized-controlled studies but has a relatively higher ocular side-effect profile such as increased risk of cataract formation and raised intraocular pressure when compared to the gold standard anti-VEGF agents. Thus, DEX implant becomes the second-line treatment option demonstrating inadequate clinical response to anti-VEGF therapy. However, it can be preferred as the first-line treatment in vitrectomized and pseudophakic eyes. Even in some selected conditions DEX implant is favored over anti-VEGF agents where the use of VEGF-inhibitors is either inappropriate or contraindicated such as the patients with a recent history of a major cardiovascular or cerebrovascular event, pregnancy and noncompliant to frequent visits. This mini-review briefly overviews the efficacy, safety profile and complications of DEX implant and summarizes the outcome of DEX implant administration in major clinical studies on DME treatment.

Keywords: Dexamethasone implant, Diabetic macular edema, Diabetic retinopathy, Drug-delivery system, Glaucoma, Pharmacotherapy

Core Tip: Administration of dexamethasone (DEX) implant is among the main therapeutic alternatives for treating the diabetic macular edema (DME). Though DEX implant provides a long-standing anatomic and visual improvement, implant induced cataract progression and intraocular pressure elevation limit its clinical use as the first-line treatment but DEX implant can sometimes be the preferred option in previously vitrectomized eyes, pseudophakic eyes, and in some specific conditions where the use of vascular endothelial growth factor inhibitors is either contraindicated or suboptimal. In this mini-review, we overviewed the randomized-controlled trials, real-life clinical experiences, and meta-analyses on DEX implant treatment in DME.