Subthreshold Grid Laser Treatment for Clinically Significant Diabetic Macular Edema

Purpose To evaluate the effectiveness of the therapy with subthreshold grid laser treatment with infrared micropulse 810 nm diode laser for clinically significant macular edema in diabetic retinopathy (DR). Methods Prospective interventional case series, including 11 patients (11 eyes) with macular edema in DR. All the patients were treated with infrared subthreshold (no intraoperative visible endpoint) grid laser treatment. The laser was applied in the area of edema in a grid pattern over the leaking or capillary occlusion area while sparing the central of the foveal avascular zone. The patients underwent an ophthalmologic examination icluding best-corrected visual acuity (BCVA) with ETDRS charts, contrast sensitivity with Pelli-Robson chart, digital stereo fundus photography, and foveal thickness measurements by Optical coherence tomography. The planned follow-up was 12 months. Results Mean BCVA improved from 20/40 at baseline to 20/32 at 1 year control. Mean foveal thickness changed from 416µ initially to 301µ, and total macular volume from 8,45mm3 to 7,75 mm3. At the end of the follow-up 3 patient (27%) maintained the initial VA, six (55%) obtained improvement of at least 1 line, with two of them gaining two lines (18%). Conclusions Subthreshold grid laser treatment with infrared micropulse 810 nm diode laser is an effective treatment in improving and maintaining visual function in patients affected by macular edema in diabetic retinopathy for 1 year follow-up. Randomized controlled trials with longer follow up and larger number of patients are necessary to compare the effectiveness as against conventional grid laser photocoagulation.