The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

Abstract

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Keywords: DME; OCT; anti-VEGF; biomarker; corticosteroid; dexamethasone; diabetes mellitus; diabetic macular edema; diabetic maculopathy; response to treatment.

Scheme 1

Definitions and subtypes of biomarkers.

Figure 1

(Left) Patient with diabetic macular edema at baseline. The optical coherence tomography (OCT) exhibits hyperreflective foci, large cysts, subretinal fluid and a ganglion layer cyst. A vitreomacular adhesion is visible. Best-corrected visual acuity (BCVA) is 20/50. (Middle) OCT 10 days after the seventh ranibizumab injection on a monthly basis. Hyperreflective foci have significantly decreased, but large intraretinal cysts have remained, partly with homogenous hyperreflective content; some disruption of the ellipsoid zone (EZ) is visible. BCVA remained at 20/50. (Right) Four weeks after switching the patient to an intravitreal dexamethasone implant. Central retinal thickness and intraretinal cysts have significantly decreased. However, more hyperreflective foci are visible, the content of cystoid spaces is homogenously hyperreflective, and the EZ and the external limiting membrane is intact. BCVA has improved by one line to 20/40.