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José Belúcio-Neto, Renato Martins Passos, Camilla Oliveira Xavier, Joao Rafael de Oliveira Dias, Nilva Moraes, Andre M Maia; Evaluation of 577nm multispot vs 532nm single-spot panretinal photocoagulation for diabetic retinopathy: a clinical trial. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5686.
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Several laser equipments have been developed for treatment of diabetic retinopathy (DR), differing in laser wavelength and pattern of spots. The purpose of this study is to evaluate and compare patient tolerance, treatment parameters, safety and anatomical/functional outcomes in patients with DR who underwent panretinal photocoagulation (PRP) with 577nm multispot laser (Supra Scan®, Quantel Medical) versus 532nm single-spot laser (Pascal®, Topcon).
Our group designed a single-center, randomized clinical trial involving 30 eyes, including individuals with proliferative DR without previous treatment. Eyes with ocular comorbidities or previous intravitreal injection or vitrectomy were excluded. After recruitment best corrected visual acuity (Snellen), OCT, fluorescein angiography and retinography were performed. Patients were then submitted to PRP, either using 577nm multispot laser with 10-20ms exposure time (group 1) or 532nm single-spot laser with 100ms exposure time (group 2). Those exams will be repeated at 6 months and 1 year after PRP conclusion. The main outcome is regression of neovessels at 1 year and secondary outcomes are laser parameters, spots characteristics, number of sessions and patient tolerance (a subjective scale of pain and photophobia, ranging from 0 _no discomfort_ to 10 _extreme discomfort).
So far 23 patients have been recruited, 2 were excluded and 14 have completed treatment, 7 in each group. Patients included in group 1 had mean mean visual acuity of 0,5±0,2; mean maximum power used in treatment was 528,57±197,1mJ, producing 2407,7±148,1 spots in 2,7±0,8 sessions. In the first, second and third sessions, mean pain was 3,1±2,3, 4,0±3,2 and 4,25±3,0; and mean photophobia was 3,4±3,3, 4,7±4,5 and 3,7±4,3, respectively. In group 2, mean visual acuity was 0,6±0,7; mean maximum power was 386,4±158,0 mJ, with 1224,7±154,2 spots produced in 3,1±0,4 sessions. Mean pain was respectively 3,9±1,7, 5,1±2,9 and 5,9±2,5 in the first, second and third sessions respectively; and mean photophobia was 4,1±1,2, 6,3±2,1 and 6,1±2,5.
Preliminary results of this study show that 577 nm multispot laser, when compared to 532nm single-spot, requires a similar number of sessions for completing PRP and is better tolerated by patients. Follow up data will be used to compare effectiveness and anatomical outcomes between the two groups.
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