A Randomized Trial Comparing Intravitreal Triamcinolone Acetonide and Focal/Grid Photocoagulation for Diabetic Macular Edema
Received 29 April 2008; received in revised form 6 June 2008; accepted 11 June 2008. published online 28 July 2008.
Objective
To evaluate the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone in comparison with focal/grid photocoagulation for the treatment of diabetic macular edema (DME).
Design
Multicenter, randomized clinical trial.
Participants
Eight hundred forty study eyes of 693 subjects with DME involving the fovea and with visual acuity of 20/40 to 20/320.
Methods
Eyes were randomized to focal/grid photocoagulation (n = 330), 1 mg intravitreal triamcinolone (n = 256), or 4 mg intravitreal triamcinolone (n = 254). Retreatment was given for persistent or new edema at 4-month intervals. The primary outcome was evaluated at 2 years.
Main Outcome Measures
Visual acuity measured with the electronic Early Treatment Diabetic Retinopathy Study method (primary), optical coherence tomography-measured retinal thickness (secondary), and safety.
Results
At 4 months, mean visual acuity was better in the 4-mg triamcinolone group than in either the laser group (P<0.001) or the 1-mg triamcinolone group (P = 0.001). By 1 year, there were no significant differences among groups in mean visual acuity. At the 16-month visit and extending through the primary outcome visit at 2 years, mean visual acuity was better in the laser group than in the other 2 groups (at 2 years, P = 0.02 comparing the laser and 1-mg groups, P = 0.002 comparing the laser and 4-mg groups, and P = 0.49 comparing the 1-mg and 4-mg groups). Treatment group differences in the visual acuity outcome could not be attributed solely to cataract formation. Optical coherence tomography results generally paralleled the visual acuity results. Intraocular pressure increased from baseline by 10 mmHg or more at any visit in 4%, 16%, and 33% of eyes in the 3 treatment groups, respectively, and cataract surgery was performed in 13%, 23%, and 51% of eyes in the 3 treatment groups, respectively.
Conclusions
Over a 2-year period, focal/grid photocoagulation is more effective and has fewer side effects than 1-mg or 4-mg doses of preservative-free intravitreal triamcinolone for most patients with DME who have characteristics similar to the cohort in this clinical trial. The results of this study also support that focal/grid photocoagulation currently should be the benchmark against which other treatments are compared in clinical trials of DME.
Financial Disclosure(s)
Proprietary or commercial disclosure may be found after the references.
Manuscript no. 2008-530.
Available online: July 26, 2008.
A list of the members of the Diabetic Retinopathy Clinical Research Network participating in the trial appears in the online Appendix 1 available at http://aaojournal.org.
Writing Committee. Lead authors: Michael S. Ip, Allison R. Edwards, Roy W. Beck, Neil M. Bressler; additional writing committee members (in alphabetical order): Lloyd Paul Aiello, David J. Browning, Michael J. Elman, Scott M. Friedman, Frederick L. Ferris, Adam R. Glassman, Craig Kollman, Angela Price.
A complete list of all DRCR.net investigator financial disclosures can be found at www.drcr.net.
Supported through a cooperative agreement from the National Eye Institute and the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland (grant nos.: EY14231, EY14269, EY14229).
The funding organization participated in oversight of the conduct of the study and review of the manuscript but not directly in the design of the study, the conduct of the study, data collection, data management, data analysis, interpretation of the data, or preparation of the manuscript. Allergan, Inc., provided the triamcinolone and topical antibiotics after successfully competing for a request for proposals issued by DRCR.net for a company to provide a preservative-free triamcinolone for the study. As per the DRCR.net Industry Collaboration Guidelines (available at www.drcr.net), the DRCR.net had complete control over the design of the protocol, ownership of the data, and all editorial content of presentations and publications related to the protocol. Allergan, Inc., has provided unrestricted funds to DRCR.net for its discretionary use.
Correspondence: Michael S. Ip, MD, c/o Jaeb Center for Health Research, 15310 Amberly Drive, Suite 350, Tampa, FL 33647. E-mail: drcrnetB3@jaeb.org.
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