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R. J. Casson, G. Raymond, H. S. Newland, J. Gilhotra, T. Gray, J. Runciman, N. Jaross, M. Plunkett; A Pilot, Prospective, Randomized Clinical Trial of a New Nanopulse Retinal Laser versus Conventional Photocoagulation for the Treatment of Diabetic Macular Edema. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5843.
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The Retinal Regeneration Therapy (2RT) laser is a new, nanopulse retinal laser that experimentally causes minimal injury to sensory retina at clinically relevant settings. We compared the safety and efficacy of 2RT with photocoagulative (control) laser in a pilot, prospective, randomized, non-inferiority study.
Patients with previously untreated diabetic macular edema (DME) were randomized to receive either 2RT or control laser. Retinal thickness and logMAR acuity (VA) were recorded at baseline and 3 and 6 months after treatment (3-month data is shown here). The outcomes were the difference in retinal thickness reduction measured by optical coherence tomography (OCT) between the control and 2RT groups (ΔOCT), and the difference in VA change between the control and 2RT groups (ΔVA). Non-inferiority was defined as the one-sided 97.5% confidence intervals (CIs) of ΔOCT > -35 µm (no more than 35 µm more reduction in the control group), and a ΔVA > -.06 (VA change after 2RT no more than 3 letters worse than the control group change). An analysis of covariance (ANCOVA) model was used to determine the CIs for ΔOCT and ΔVA, adjusting for regression to the mean.The control laser was applied in a conventional focal/grid pattern based on ETDRS protocol. 2RT was applied in a grid pattern so that a barely discernible retinal reaction was visible.
There were 22 eyes in the 2RT group and 18 in the control group, with no significant age and gender differences. The baseline mean retinal thickness was 339 ± 96 µm in the 2RT group and 318 ± 70 µm in the control group; the mean retinal thickness change in the 2RT group was -44 ± 94 µm, and in the control group was -23 ± 52 µm. The adjusted ΔOCT was 2.5 µm (in favour of 2RT) with a one-sided 97.5% CI of -29.6 µm. The baseline mean VA was .21 ± .23 in the 2RT group and .12 ± .23 in the control group; the corresponding 3-month mean VAs were .18 ± .27 and .12 ± .24, respectively. The ΔVA was -0.03 (1.5 letter improvement in favour of 2RT) with a one-sided 97.5% CI such that 2RT was no more than 2 letters worse than the control laser). The safety profile of 2RT was excellent.
In this pilot study, 2RT was safe and at least as clinically effective in the treatment of DME as conventional laser. Given that 2RT causes minimal injury to overlying retina, and can potentially treat edema closer to the fovea, 2RT warrants further evaluation in a larger study.
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