Ranibizumab vs Dexamethasone Implant in Vitrectomized Eyes With Diabetic Macular Edema

Vitrectomy is required for removal of vitreous hemorrhage or retinal traction tissue in some patients with proliferative diabetic retinopathy. Post-vitrectomy macular edema may occur in these diabetic patients. Intravitreal injections of anti-VEGF agents or corticosteroid are required for treating diabetic macular edema (DME) in vitrectomized eyes. Intraocular levels of various cytokines may alter in the diabetic eyes following vitrectomy. Pharmacokinetics may be different between various intraocular agents in vitrectomized eyes. Herein our study will prospectively randomize to compare the clinical behavior between intravitreal ranibizumab (IVR) and intravitreal dexamethasone implant (IDI) in vitrectomized patients with DME. To our knowledge, it is the first study involving such subject.

Pseudophakic vitrectomized eyes with treatment-naïve center-involved DME will be enrolled with one eye in each patient. They are randomized into one group receiving IDI every 3 to 4 months, and the other group undergoing IVR using 3 monthly plus treat-and-extend injections all with monthly follow-up for 6 months. Switch of intravitreal drugs or deferred macular laser is not allowed. Primary outcome measures include change in central foveal thickness (CFT) in 1 mm by spectral-domain optic coherence tomography, and best corrected visual acuity (BCVA) at Month 6. Primary outcome measures include change in CFT and BCVA at Month 6. Injection number, BCVA, CFT, post-injection complications, and IOP are recorded and compared with Wilcoxon signed rank test within the group and Wilcoxon rank sum test between groups. Fisher's exact test is used for categorical comparison between groups. P value less than 0.05 is considered significant.

Inclusion criteria

• Age more than 18 years
• Glycosylated hemoglobin (HbA1c) less than 10.0%
• Best-corrected visual acuity (BCVA) between 20/400 to 20/40
• Central foveal thickness (CFT) more than 300 μm in the 1-mm central macular subfield on spectral domain optical coherence tomography (SD-OCT, CIRRUS™ HD-OCT 5000, Carl Zeiss Meditec Inc., Dublin, CA, USA) using 6 radial line scans through the fovea
• Macular leakage on fundus fluorescein angiography (HRA2, Heidelberg Engineering GmbH, Germany)
• The DME pattern can include submacular fluid, cystoid change, and diffuse macular thickening
• All have proliferative diabetic retinopathy treated by panretinal photocoagulation receiving prior vitrectomy without silicone oil or gas inside the vitreous cavity
• Prior intraocular surgery performed as least 3 months ago

Exclusion criteria

• Pregnant or nursing women
• The patients with the history of thromboembolic events or major surgery within the previous 3 months
• Presence of anterior chamber intraocular lens or subluxated/dislocated posterior chamber intraocular lens
• Presence of uncontrolled hypertension
• Known coagulation abnormalities or current use of anticoagulative medication other than aspirin
• Prior macular photocoagulation or photodynamic therapy
• Presence of active infectious disease or intraocular inflammation
• Intraocular pressure more than 20 mmHg or glaucoma history
• Presence of iris neovascularization/vitreous hemorrhage.
• The DME pattern with accompanying macular traction by epiretinal membrane or posterior hyaloid