Safety and efficacy outcomes from a five-year study indicate that intravitreal triamcinolone can be an appropriate treatment in selected patients with advanced diabetic macular edema. Beneficial effects persisted throughout the study period, and no unexpected adverse events were seen.
"The beneficial effects of IVTA that we found at 2 years generally held up for 5 years, and no new unforeseen adverse events were detected in this group, which has the longest follow-up yet described for IVTA," said Dr. Gillies, associate professor, Department of Clinical Ophthalmology and Eye Health, Sydney Eye Hospital, The University of Sydney, New South Wales, Australia.
Initially, 69 eyes of 43 patients were randomly assigned to receive active treatment consisting of 4 mg IVTA injections (n = 34) or placebo (n = 35), a subconjunctival injection of saline. After 2 years of participation in this double-masked trial, all patients were eligible for a 3-year, open-label extension in which they could receive IVTA therapy if there was persistent visual impairment with central macular thickness (CMT) greater than 275 μm.
First 2 years
At the 3-month follow-up from baseline, 18 of 33 eyes (55%) treated with IVTA had gained five or more letters of best-corrected visual acuity (BCVA) compared with five of 32 eyes (16%) in the control arm of the study (p = 0.002). ME was reduced by one or more grades in 25 of 33 eyes (75%) in the treatment group and five of 32 (16%) control eyes (p = 0.0001). Results of optical coherence tomography (OCT) showed significant differences between the two groups at that early timepoint. A mean reduction in central retinal thickness of 152 μm was observed in 21 eyes in the treatment group versus 36 μm in 20 placebo eyes.
At 24 months, data were available for 60 of 69 eyes (87%) of 41 patients. Although eyes in the IVTA group continued to have better outcomes, the gap between the two study arms narrowed as a higher proportion of eyes in the placebo group also had improvement on various measures, Dr. Gillies said.
Outcomes showed that improvement of five or more letters of BCVA occurred in 19 of 34 (56%) of the IVTA-treated eyes and nine of 35 (26%) placebo-treated eyes (p = 0.006). Mean improvement in BCVA was 5.7 letters greater in the treated eyes than in the control eyes.
In other findings, a higher proportion of eyes in the IVTA group experienced an increase in IOP ≥5 mm Hg or required glaucoma medication. Elevated IOP was observed in 23 of 34 (68%) of the IVTA eyes versus three of 30 (10%) eyes in the control group. Glaucoma medication was indicated in 15 of 34 treated eyes (44%) compared with one of 30 (3%) untreated eyes.
Based on the 2-year outcomes, investigators concluded that IVTA treatment was proven and began the extension phase of the trial in which treatment was available to patients from either group who met specific criteria. For that portion of the study, additional treatment was warranted for 12 of 29 eyes (41%) in the initial-IVTA group and 10 of 28 eyes (36%) in the placebo group.
The last observation was carried forward on all patients. Because this type of analysis can lead to bias, the investigators first treated patients without 5-year data as if they had all achieved the primary outcome and secondly as if none had achieved it. That method made no difference in the results, according to Dr. Gillies.