Purpose: To evaluate the influence of different confounding factors on the effect of intravitreal triamcinolone acetonide injection for refractory diabetic macular edema.
Methods: In a prospective placebo-controlled randomized clinical trial, 88 eyes with refractory diabetic macular edema were randomly assigned into two groups including 45 in the treatment group (4 mg intravitreal triamcinolone acetonide) and 43 in the placebo group. Multivariate analysis was performed for three main outcomes, including visual acuity, central macular thickness, and the amount of hard exudates. Confounding factors that showed some effect on the main outcomes were used for building multivariate models.
Results: It was revealed that blood urea nitrogen, fasting blood sugar, serum cholesterol, initial visual acuity, presence of cystoid macular edema, amount of hard exudates, and size of foveal avascular zone had some influence on visual acuity outcome; previous macular photocoagulation, serum cholesterol, baseline central macular thickness, initial intraocular pressure, amount of hard exudates, and size of foveal avascular zone had some influence on central macular thickness changes; and serum cholesterol, baseline central macular thickness, and amount of hard exudates had some influence on hard exudates in both groups. Size of foveal avascular zone, initial intraocular pressure, amount of hard exudates, and baseline central macular thickness also had an additive effect on the outcomes in the treatment group.
Conclusions: Many confounding factors may influence the effect of intravitreal triamcinolone. These factors should be considered when adopting intravitreal triamcinolone as a treatment strategy for refractory diabetic macular edema.