Treatment of diabetic retinopathy: Recent advances and unresolved challenges

Abstract

Diabetic retinopathy (DR) is the leading cause of blindness in industrialized countries. Remarkable advances in the diagnosis and treatment of DR have been made during the past 30 years, but several important management questions and treatment deficiencies remain unanswered. The global diabetes epidemic threatens to overwhelm resources and increase the incidence of blindness, necessitating the development of innovative programs to diagnose and treat patients. The introduction and rapid adoption of intravitreal pharmacologic agents, particularly drugs that block the actions of vascular endothelial growth factor (VEGF) and corticosteroids, have changed the goal of DR treatment from stabilization of vision to improvement. Anti-VEGF injections improve visual acuity in patients with diabetic macular edema (DME) from 8-12 letters and improvements with corticosteroids are only slightly less. Unfortunately, a third of patients have an incomplete response to anti-VEGF therapy, but the best second-line therapy remains unknown. Current first-line therapy requires monthly visits and injections; longer acting therapies are needed to free up healthcare resources and improve patient compliance. VEGF suppression may be as effective as panretinal photocoagulation (PRP) for proliferative diabetic retinopathy, but more studies are needed before PRP is abandoned. For over 30 years laser was the mainstay for the treatment of DME, but recent studies question its role in the pharmacologic era. Aggressive treatment improves vision in most patients, but many still do not achieve reading and driving vision. New drugs are needed to add to gains achieved with available therapies.

Keywords: Aflibercept; Bevacizumab; Dexamethasone delivery system; Diabetic macular edema; Diabetic retinopathy; Fluocinolone acetonide insert; Macular photocoagulation; Panretinal photocoagulation; Proliferative diabetic retinopathy; Ranibizumab.

Figures

Figure 1

This drawing identifies many of the unresolved treatment questions pertaining to the evaluation and treatment of patients with diabetic retinopathy. The question marks highlight areas of controversy that are discussed in greater detail in the manuscript. VEGF: Vascular endothelial growth factor.

Figure 2

This figure shows sequential optical coherence tomography scans of a patient with diabetic macular edema. At baseline (A and B) the patient was given a series of 5 monthly injections of bevacizumab with no significant improvement in macular edema (C and D); one month after a single injection of the dexamethasone delivery system, the volume of edema had significantly improved (E and F).