Alireza Ramezani, (Tehran, Iran), Homa Tabatabaei, MD (Tehran, Iran), Hamid Ahmadieh, MD (Tehran, Iran)

PURPOSE:

The therapeutic effect of intravitreal triamcinolone (IVT) on diabetic macular edema (DME), which is a chronic disease, has been shown to be temporary. This study was conducted to compare IVT treatment effect with the natural course of refractory DME in a particular group of the eyes. We chose one group for both interventions to minimize the influence of systemic and ocular confounding factors.

METHODS:

In a prospective interventional case series, 25 eyes with refractory DME which had been allocated to the sham group of a previous clinical trial underwent new examination and optical coherence tomography about 9 months after their first enrollment. Twenty eyes which met the inclusion criteria, visual acuity (VA) < 20/50 and central macular thickness (CMT) > 200 μ, received 4 mg IVT. Evaluation was repeated after 2 and 4 months to imitate the similar examination intervals after sham injection. Variable changes subsequent to the sham injection were considered as the natural course of disease. VA and CMT changes following IVT were compared with the corresponding changes after sham injection.

RESULTS:

The comparison of VA changes between and within the two interventions (IVT and sham injection) did not show statistically significant difference. However, there was a minor deterioration of VA following sham injection (0.07 and 0.06 logMAR at months 2 and 4 respectively) and a slight improvement (0.04 logMAR) by 2 months after IVT injection. Until 4
months, there was a reduction (-63 μ) in mean CMT subsequent to IVT injection compared to a mild increase (+40 μ) after receiving sham intervention; however, these differences within each intervention were not statistically significant (paired t test). Comparisons of thickness changes between the two interventions did not show significant difference either (t test),
except in one stage. The difference of changes between months 0 and 4 (52 μ increase after sham vs. 262 μ reduction after IVT) was significant (P=0.014), which implied on CMT reduction after IVT treatment in eyes which had been followed without any treatment for 9 months.

CONCLUSION:

This study demonstrated the beneficial effect of IVT on DME. However, this effect was evident mostly on CMT rather than on VA. Considering the stable nature of VA and macular thickness in patients with refractory DME, and the insignificant temporary effect of IVT on VA, IVT is not recommended as a routine treatment modality for such cases. CHART 1: Visual acuity changes after sham and IVT injections. CHART 2: Central macular thickness changes after sham and IVT injections.