Abstract
Purpose: :
To report clinical results of subthreshold micropulse diode laser (MDL) compared to conventional green argon laser (CGL) for diabetic macular edema (DME) in order to determine the efficacy and the safety of MDL vs CGL.
Methods: :
Between April 2009 and November 2010 we enrolled 56 patients (68 eyes) with clinically significant diabetic macular edema. Complete clinical examination was performed, best-corrected visual acuity (BCVA) using ETDRS charts and mean foveal thickness (MFT) using Stratus OCT (Zeiss) were recorded at baseline, 3, 6, 9 and 12-month. 20 eyes were treated with 810-nm micropulse diode laser (Iridex Oculite SLx, Iridex Corp.) using the same parameters for all treatments (5% duty, 920 mW). Confluent treatment of thickened areas avoiding the fovea was performed. Booster therapy with single intravitreal injection of Bevacizumab 1.25 mg (Bev) or posterior juxtascleral infusion of Triamcinolone 40 mg and sodium hyaluronate 10 mg (1.5 mL) (T) were performed before diode laser when baseline retinal thickness was >400 µm and >600 µm respectively (7 eyes MDL+Bev, 7 eyes MDL+T). 34 eyes were treated using conventional argon laser with a grid pattern of threshold burns. The different treatment groups were compared with multiple regression analysis using baseline OCT and BCVA as a covariate (both showing statistical significance, P<0.0005 and P<0.0001, respectively).
Results: :
BCVA was stable in MDL groups and worsened at the 12-month in CGL (+0.1 LogMar) but there was no significant difference between the 4 treatment groups (MDL, P=0.44; MDL+Bev, P=0.14; MDL+T, P=0.81; CGL, P=0.16). MFT decreased in all groups (mean change -40 µm in MDL group, -84 µm in MDL+Bev group, -73 µm in MDL+T group and -77 µm in CGL group). These changes in MFT from baseline were not statistically significant (P=0.27, P=0.50, P=0.34, P=0.0029, respectively).
Conclusions: :
Micropulse subthreshold diode laser seems to be as effective as conventional green argon laser in the treatment of DME. The results showed a similar beneficial effect in stabilization of visual acuity and reduction of macular thickness, avoiding retinal damage of scarring burns. Bevacizumab and Triamcinolone, used as booster therapy, are effective in reducing macular thickness when used in combination with MDL treatment.
Keywords: laser • edema • diabetic retinopathy