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A. Kaines, S. Fraser-Bell, M. Michelaelides, C. Egan, P. Hykin; Diabetic Macular Oedema: A Prospective Randomised Trial of Management With Intravitreal Bevacizumab (avastin) versus Conventional Laser Therapy: A Description of Methodology. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3505.
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This study is designed to study the efficacy and safety of repeated intravitreal bevacizumab in improving visual acuity in diabetic patients with persistent (despite laser treatment) clinically significant macula oedema compared to further ETDRS laser.
Single centre randomised controlled trial, Baseline examination will include of best corrected visual acuity (BCVA), optical coherence tomography (OCT), 7 field retina colours and fluorescein angiography. Randomisation will be on a 1:1 basis to either intravitreal bevacizumab or macular laser photocoagulation.Follow up investigation and treatment visits will be at weeks 6, 12, 18, 24, 30, 36, 42, 48 and 52 weeks for bevacizumab and weeks 18, 36, and 52 for laser subjects. Follow up investigation will include BCVA and OCT. Follow up fluorescein angiograms will be performed at 4, 8 and 12 months to assess foveal vascularity. At the final visit additional 7 field colour photos will be repeated.Patients with angina, uncontrolled blood pressure or having suffered a myocardial infarction, cerebro-vascular accident or transient ischaemic attack in the previous 6 months will be excluded.Patients of either gender aged 18 or above with best corrected visual acuity in the study eye must be between 69 and 35 ETDRS letter score at 4m (Snellen equivalent of <6/12 and 6/60 or better) and patients must have had at least one prior macular laser therapy.Severe macular ischaemia and co-existing ocular disease may preclude entry into the study. 80 patients randomised to 2 groups.The predicted benefit of laser is a gain of 1.7 ETDRS letters at 12 months. The predicted gain of Avastin is 10 ETDRS letters at 12 months. The assumed standard deviation is 12.3.When the sample size in each group is 36, there will be an 80% power to detect a difference in means of -8.300 ( the difference between group 1 mean of 1.700 and a Group 2 mean of 10.000) assuming that the common standard deviation is 12.3000 using a two group t-test with a 0.50 two sided significance level. Assuming a 10% dropout rate before time t, this will require 40 patients per treatment group.Patients will be stratified at entry for visual acuity.
The Primary End Point is comparison of mean ETDRS BCVA at 12 months between the bevacizumab and laser arms.
Recruitment is expected to be complete in April 2008. Analyses will be performed at 12 months.
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