Dexamethasone Implant Improves Visual Acuity and Decreases Macular Thickness in Diabetic Macular Edema

Placement of a sustained-release dexamethasone implant (Ozurdex/Allergan) in 29 patients with persistent diabetic macular edema (DME) resulted in a significant improvement in visual acuity and a significant decrease in central macular thickness 6 months after implantation.

In an observational study reported in Ophthalmologica, a mean gain in visual acuity of nearly 14 letters and a mean reduction in central macular thickness of 159 μm were both found 6 months after Ozurdex implantation (P < 0.0001 for both). Moreover, during 18 months of follow-up, most patients (17, or 59%) experienced an improvement in visual acuity of 15 letters or more.

About half (14, or 48%) of the patients in the study had not been treated previously for DME, and the majority (22, or 76%) had not been treated with anti-vascular endothelial growth factor (anti-VEGF) injections. No serious adverse events were reported during the study.

The investigators concluded that the efficacy, safety, and manageable adverse events found in the study, coupled with the much decreased requirement for injections with Ozurdex compared with anti-VEGF agents, confirmed the usefulness of Ozurdex in treating persistent DME.

A separately published report in the American Journal of Ophthalmology provided insight into the molecular mechanism by which dexamethasone implants reduce DME. Analysis of results from the Diabetic Macular Edema Treated with Ozurdex (DMEO) Trial found that Ozurdex-related reduction in DME correlated with reduction in the pro-permeability factors angiopoietin-2, hepatocyte growth factor, and endocrine gland-VEGF.

In this prospective, randomized, cross-over trial, 20 DME patients who were randomly assigned to receive either Ozurdex or anti-VEGF therapy had aqueous taps and spectral domain optical coherence tomography at baseline and every 4 weeks for 28 weeks. Levels of 55 vasoactive proteins were measured in the aqueous with a protein array before therapy and every 4 weeks thereafter to identify potential pro-permeability factors that contribute to DME. After 16 weeks, cross-over treatment provided data on changes in levels of these proteins after each intervention in all 20 patients.

A significant correlation was found between changes in excess foveal thickness after Ozurdex implantation and changes in aqueous levels of angiopoietin-2 (P = 0.001), hepatocyte growth factor (P = 0.02), and endocrine-gland VEGF (P =<0.001). A correlation was also found between edema reduction and reduction in aqueous levels of prolactin, insulin-like growth factor binding protein-3, and matrix metalloproteinase-9 after anti-VEGF therapy as well as after Ozurdex implantation. However, the investigators interpreted changes in levels of the latter three proteins as a result rather than a cause of edema reduction.

The investigators concluded that additional study is needed to investigate the contribution of the pro-permeability factors angiopoietin-2, hepatocyte growth factor, and endocrine gland-VEGF to chronic DME.