Background: The present study was performed to compare the effects of pars plana vitrectomy (PPV) and single intravitreaous triamcinolone acetonide (IVTA) on diabetic macular edema (DME) in paired eyes.
Methods: Prospective comparative study on randomized paired-eyes was carried out at two hospitals. Forty eyes of 20 patients with bilateral DME were included. One randomly-selected eye was treated with PPV (PPV group), and the other eye was treated with IVTA (4 mg, IVTA group). The central macular thickness (CMT) measured by optical coherence tomography (OCT) and best-corrected visual acuity (BCVA) were monitored for 12 months after treatment. Changes from baseline and differences between groups were analyzed using a mixed model.
Results: At 1 and 3 months, CMT decreased significantly in the IVTA group compared to baseline (p < 0.0001 both), but CMT then increased gradually and no significant difference was found at 12 months (p = 0.90). In the PPV group, CMT decreased continuously and reached a significant level at 12 months (p < 0.0001). CMT of the IVTA group was significantly less than that of the PPV group at 1 month (p = 0.009); however, there was no significant difference at 3 months. Conversely, CMT was significantly less in the PPV group than in the IVTA group at 12 months (p = 0.0003). The changes of BCVA paralleled those of CMT, but no significant difference was detected between baseline BCVA and any time point.
Conclusions: Despite the short-term improvement, DME recurred 6 months after IVTA, while it remained resolved after PPV. Although this study did not reveal a significant change of BCVA with either treatment, PPV resolved DME more effectively than IVTA at 1 year.