Efficacy and safety of postvitrectomy intravitreal triamcinolone therapy for diabetic macular edema

After vitrectomy, diffusion and clearance rates of numerous drugs are increased, leading to a shorter intravitreal half-life. This raises doubts about the efficacy of intravitreal therapies, as retina specialists generally believe that a shorter half-life compromises the drugs' therapeutic effect. We conducted a study to evaluate the functional and anatomical effect of intravitreal triamcinolone acetonide therapy (IVTA) in previously vitrectomized eyes with diabetic macular edema (DME).

In this retrospective, multicenter case series study including vitrectomized patients with DME who underwent IVTA injections, central macular thickness (CMT) measured with spectral-domain optical coherence tomography and best-corrected visual acuity (BCVA) in Early Treatment Diabetic Retinopathy Study letters were evaluated after each procedure. All relevant medical data were collected, including previous ophthalmologic treatments and comorbidities.

Twenty vitrectomized eyes of 20 patients, mean age 58.1 years (range 40-72 years), were enrolled in the study. All patients presented DME and received at least one IVTA injection. Mean time between pars plana vitrectomy and IVTA was 12.9 ± 8.7 months. Mean pretreatment and posttreatment CMT was 438.8 ± 90.8 μm and 301.2 ± 76.2 μm, respectively, a difference that reached statistical significance (p<0.001). Mean gain in BCVA letter score was 7.83 ± 14.9 letters after treatment (p = 0.039). Mean intraocular pressure was significantly increased after IVTA (17.2 ± 1.9 mm Hg at baseline vs 21.2 ± 4.59 mm Hg after IVTA, p = 0.002).

A positive anatomical and functional effect was observed in our cohort. Our results suggest that, despite prior vitrectomy, triamcinolone remains a valid therapeutic approach for eyes with persistent DME. Further prospective randomized studies with larger patient samples are needed to validate this conclusion.