ABSTRACT

Diabetic macular edema is the most common cause of visual impairment in patients with diabetes mellitus. The pathogenesis of macular edema is complex and multifactorial. For many years, laser photocoagulation has been considered the standard therapy for the treatment of diabetic macular edema; however, few patients achieve significant improvements in visual acuity. Today the intravitreal administration of anti-inflammatory or anti-angiogenic agents together with the use of laser photocoagulation represents the standard of care for the treatment of this complication. The intravitreal route of administration minimizes the systemic side effects of corticosteroids. Steroid-related ocular side effects are elevated intraocular pressure and cataract, while injection-related complications include endophthalmitis, vitreous hemorrhage, and retinal detachment. In order to reduce the risks and complications, intravitreal implants have been developed recently to provide sustained release of corticosteroids and reduce repeated injections for the management of diabetic macular edema. In this review, the efficacy, safety, and therapeutic potential of intravitreal corticosteroids in diabetic macular edema are discussed with a review of recent literature.

Introduction

Diabetic macular edema (DME) is the leading cause of vision loss in patients with diabetic retinopathy (DR). In the WESDR (Wisconsin Epidemiologic Study of Diabetic Retinopathy), the 10-year incidence of DME was 20.1% among patients with type 1 diabetes, 13.9% among type 2 diabetics using insulin, and 25.4% among type 2 diabetes patients not using insulin.1 Without timely and appropriate treatment, DME leads to permanent vision loss. Although the rate of serious vision loss due to DME is believed to have fallen in recent years, an additional 12,000-24,000 new cases are reported each year.2

Grid and focal laser photocoagulation have long been accepted as the standard treatment for vision loss associated with DME. It has been shown that laser photocoagulation reduces the risk of moderate vision loss in DME; however, many patients are unable to regain lost vision and the procedure is not effective in all DME patients.3

With the development of intravitreal agents such as anti-vascular endothelial growth factor (anti-VEGF) and steroids, new strategies are now recommended for the management of this complex disease. While intravitreal implantation offers potential visual gains compared to laser interventions, repeated application confers risks in terms of both drug- and surgery-related side effects.3 With the longer duration of effect provided by intravitreal implants, the aim is to provide better visual recovery and fewer side effects. This review discusses the pathogenesis of DME, the rationale behind the use of corticosteroids, and current approaches to steroid use in the management of DME.