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D. Lavinsky, J. A. Cardillo, L. A. S. Melo Jr, A. J. Dare, M. E. Farah, R. Belfort, Jr.; Spectral Domain OCT and Autofluorescence Findings of Modified ETDRS and High Density Subthreshold Infrared Micro Pulsed Photocoagulation for Diabetic Macular Edema. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4677.
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© ARVO (1962-2015); The Authors (2016-present)
To compare spectral domain OCT and autofluorescence findings of two laser photocoagulation techniques for treatment of diabetic macular edema: the modified Early Treatment Diabetic Retinopathy Study (ETDRS) direct/ grid photocoagulation technique and high density (increased number of spots to potentially enhance the area of retinal pigment epithelium activation) sub-threshold micro pulsed 810 nm diode laser technique.
Prospective, double-masked, controlled trial, 30 subjects with previously untreated diabetic macular edema randomly assigned to receive laser photocoagulation by the modified ETDRS Study (direct/ grid photocoagulation) in16 eyes or high density micro pulsed technique (Opto FastPulsetm Laser) in 14 eyes. Visual acuity, fluorescein angiography, autofluorescence (FAF, 488nm), near infra-red autofluorescence (NIRFAF, 790 nm) and spectral domain optical coherence tomography (OCT) were obtained at baseline and at 1, 3 and 6 months. Main outcome were accessed by OCT and FAF/ NIRFAF.
No changes to retinal pigment endothelium (RPE) and photoreceptors were observed by OCT or FAF/ NIRFAF of the high density treatment group laser spots. In the modified ETDRS group we could clearly identify every spot by SD-OCT, FAF and NIRFAF, although a low intensity strategy (light grey) was used. SD-OCT showed an increased reflectivity in the RPE cells, which included the outer segment of the photoreceptors, although in the majority of cases the OS/IS line was present. There was no increase in size or area of laser spots in the follow up period.FAF and NIRFAF showed initially a decreased signal, however in time we could observe and increase in FAF and NIRFAF. No difference in central macular thickness and visual acuity was identified between groups.
These findings do not support the use of sub-threshold laser treatment of diabetic macular edema, but imply a short-term clinical performance comparable to the modified ETDRS technique, with no scarring observable with SD-OCT and FAF/NIRFAF. OCT findings suggest that a light treatment with continuous laser could selectively treat the RPE minimizing damage to the photoreceptors. The precise role of sub-threshold and threshold laser treatment may become more defined in further studies.
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