Short-term outcomes of intravitreal dexamethasone in relation to biomarkers in diabetic macular edema

Purpose: The purpose of this study was to determine the effects of dexamethasone implant (0.7 mg) on biomarkers such as hyper-reflective dots, external limiting membrane integrity and disorganization of retinal inner layers in treatment-naïve patients, patients who received less than three anti-vascular endothelial growth factor injections and non-responder cases with diabetic macular edema and its effects on edema and visual acuity.

Methods: This is a prospective study of treatment-naïve patients, patients who received less than three anti-vascular endothelial growth factor injections and non-responder patients with diabetic macular edema, treated with single dexamethasone implant. Pre- and post-injection-based best-corrected visual acuity, central macular thickness, hyper-reflective dots, external limiting membrane integrity and disorganization of retinal inner layers were assessed.

Results: A total of 27 diabetic macular edema eyes, including 9 non-responder eyes, 9 eyes which received less than three anti-vascular endothelial growth factor injections and 9 treatment-naïve eyes, were included in this study. Baseline hyper-reflective dots were 22.22 ± 11.76, 30 ± 7.91 and 19.44 ± 8.82 which reduced to 3.33 ± 1.32, 9 ± 8.35 and 8.78 ± 2.53 four months after implant in treatment-naïve patients, patients who received less than three anti-vascular endothelial growth factor injections and non-responder cases, respectively. Baseline central macular thickness was 589.44 ± 175.37, 537 ± 181.81 and 673.11 ± 138.24 and the central macular thickness after dexamethasone implant was 272.11 ± 39.00, 336.44 ± 132.88 and 524.00 ± 200.39 in treatment-naïve patients, patients who received less than three anti-vascular endothelial growth factor injections and non-responder cases, respectively. External limiting membrane integrity was restored in two patients in each group, whereas two patients with disorganization of retinal inner layers in treatment-naïve group showed reorganization of retinal structures after treatment with dexamethasone implant.

Conclusion: Better response to dexamethasone implant in cases with more hyper-reflective dots shows that these hyper-reflective dots can be used as a predictive biomarker. Dexamethasone implant might help in restoring external limiting membrane integrity and resolution of disorganization of retinal inner layers.

Keywords: Diabetic macular edema; diabetic retinopathy; research; retina; retinal degenerations associated with systemic disease; retinal medical therapies; retinal pathology.