Treatment of anti-vascular endothelial growth factor-resistant diabetic macular edema with dexamethasone intravitreal implant

Abstract

Purpose: To investigate the efficiency of intravitreal dexamethasone implant in patients with chronic diabetic macular edema nonresponsive to three consecutive monthly intravitreal injections of anti-vascular endothelial growth factor administered previously.

Methods: Fifteen patients (16 eyes) were included in this 4-month prospective clinical trial. Main observed outcomes were the changes between initial and monthly visits in best-corrected visual acuity, central foveal thickness, and intraocular pressure (IOP). Patients included had central foveal thickness of >225 μm (measured by optical coherence tomography) and were nonresponsive to previously administered 3 consecutive monthly intravitreal injections of 1.25-mg bevacizumab. Administration of intravitreal dexamethasone implant was performed at baseline, and patients were followed-up monthly.

Results: Statistically significant changes from baseline were observed in best-corrected visual acuity (at 2 months), central foveal thickness (at 1, 2, and 3 months), and IOP (at Months 1, 2, and 3) as follows: mean best-corrected visual acuity significantly increased from 0.29 Snellen lines at baseline to 0.39 lines after 2 months (P = 0.0381). At Months 1, 2, and 3, the mean central foveal thickness significantly decreased, from 462 μm at baseline, to 366 μm (P = 0.0343), 346 μm (P = 0.0288), and 355 μm (P = 0.0370), respectively. When compared with baseline IOP of 15.38 mmHg (12-19 mmHg), IOP increased significantly at Months 1, 2, and 3: 18.93 mmHg (range, 16-24 mmHg; P = 0.0003), 19.5 mmHg (range, 16-27 mmHg; P = 0.0003), and 17.5 mmHg (range, 15-21 mmHg; P = 0.0048), respectively.

Conclusion: Dexamethasone intravitreal implant may present an alternative option in the treatment of chronic diabetic macular edema nonresponsive to three consecutive monthly bevacizumab injections administered previously. However, IOP measures were only slightly increased. It seems that the effect of dexamethasone may last till 4 months after initial injection.