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Baltimore—A pilot investigation of a new mild macular grid photocoagulation treatment for diabetic macular edema (DME) and a study comparing intravitreal triamcinolone with laser photocoagulation are two ongoing trials being performed under the auspices of the Diabetic Retinopathy Clinical Research Network (DRCR.net), and a number of other protocols are under way, will be launched soon, or are in development, said Sharon Solomon, MD, at Current Concepts in Ophthalmology.
"DRCR.net is dedicated to facilitating multicenter clinical research trials of diabetic retinopathy, macular edema, and associated conditions. It is involved in promoting community- and academic-based clinical centers, but one of its primary initiatives is to support collaboration with industry to facilitate investigations and pursue opportunities that would not otherwise be possible. However, DRCR.net is dedicated to achieving that objective in a manner that is consistent with academic integrity and optimal clinical trial performance," said Dr. Solomon, assistant professor of ophthalmology in the retina department of Wilmer Eye Institute, Johns Hopkins University, Baltimore.
DRCR.net was formed in September 2002, and receives funding from the National Eye Institute. So far, more than 130 sites, including 68 community-based locations, are participating in DRCR.net trials. Approximately 400 investigators along with more than 800 additional study personnel are involved in the various protocols.
"The mild macular grid approach applies small, widely separated burns to both thickened and unthickened areas of the retina from 500 to 3,000 μm from the macular center, which is in contrast to the modified ETDRS photocoagulation protocol where focal/grid laser photocoagulation is applied only to areas of thickened retina that have leaking microaneursysms, diffuse leakage, or nonperfusion as assessed by fluorescein angiography," Dr. Solomon explained.
The trial enrolled patients ages 18 years and older whose study eye had clinically significant macular edema that involved or threatened to involve the macula as assessed by contact lens biomicroscopy and ocular coherence tomography (OCT). Eligible eyes had best corrected visual acuity (BCVA) of 20/400 or better and no previous focal or grid laser photocoagulation. Patients with two study eyes had one eye randomly assigned to one treatment technique and received the other treatment in the fellow eye.
The primary outcome assessment, OCT-measured change in retinal thickening, will be evaluated at 12 months. Other assessments include fundus photography, fluorescein angiography, and ETDRS visual acuity. During the first 12 months, patients with persistent DME are eligible for treatment with a fixed protocol at 15, 34, and 52 weeks.
The study has a planned 3-year duration, and during the last 2 years, recalcitrant DME is treated according to the investigator's discretion.
Enrollment began in August 2003, and closed in October 2004, with about 250 patients entered at 82 sites across 29 states.
The ongoing trial comparing intravitreal triamcinolone acetonide and laser photocoagulation is comparing steroid doses of 1 and 4 mg against the laser treatment.
"The objective of this study is to determine whether intravitreal triamcinolone acetonide injections of 1 or 4 mg produce greater benefit with an acceptable safety profile compared with macular laser photocoagulation," Dr. Solomon said.
This 3-year trial is entering patients with clinically significant macular edema who are 18 years and older. BCVA must be between 20/40 and 20/320 as measured using electronic ETDRS testing. The fellow eye has to be eligible for the study but can have acuity as poor as 20/400, and must also not have received previous treatment with intravitreal corticosteroids.