Ali R. Ramezani, MD, Hamid Ahmadieh, MD


To evaluate the influences of different confounding factors on the effect of intravitreal triamcinolone acetonide (IVTA) for refractory diabetic macular edema (DME) according to clinical, angiographic and optical coherence tomographic features.


Multivariate analysis was performed on the results of a prospective, double-masked, placebo-controlled clinical trial. In that study, 88 eyes of 60 patients with refractory DME had been randomly assigned to two groups; the treatment group (4 mg IVTA) and the placebo group. The analysis was done for three main outcomes: visual acuity (VA), central macular thickness (CMT) and the amount of hard exudates (HE). First, the effect of each probable factor on main outcomes was evaluated separately. Then the variables that showed some effect were used for building multivariate models.


In the both treated and placebo groups, factors influencing VA were blood urea, blood sugar, serum cholesterol, initial VA, presence of cystoid macular edema, amount of HE, and size of foveal avascular zone (FAZ). Factors influencing CMT changes included previous macular photocoagulation, serum cholesterol, baseline CMT, initial intraocular pressure, and amount of HE and size of FAZ. Factors affecting HE were serum cholesterol, baseline CMT, and amount of HE. The factors that had an additive effect only on treated eyes were size of FAZ, initial intraocular pressure, amount of HE, and baseline CMT.


There are many confounding factors that should be considered in adopting IVTA as a treatment strategy for refractory DME and in predicting outcomes.

Take-home message:

In treating diabetic macular edema, severe cases, such as eyes with higher CMT, more HE, and ischemia, or eyes with CME, demonstrate greater response to IVTA.