Short pulse grid and subthreshold micropulse laser (the sandwich grid) plus intravitreal ranibizumab for the treatment of diabetic macular edema

Abstract

Abstract Objective To investigate the effects of two laser treatment procedures combined, short pulse grid laser (SP) and subthreshold micropulse laser (MP) (the sandwich grid [SWG] technique), plus intravitreal ranibizumab (IVR) on central subfield thickness (CSFT), best-corrected visual acuity (BCVA) and macular sensitivity in patients with diabetic macular edema (DME). Methods Forty-five eyes (of 33 patients) with center-involving DME were treated with the SWG laser technique plus IVR and followed for 12 months. Laser treatment was performed at baseline: SP laser spots were placed in a grid pattern in the macular area (500 µm from the fovea) according to the extension of DME; subsequently, MP laser was delivered up to the edge of the fovea. MP laser re-treatment sessions could be performed every 3 months if DME was present and CSFT was ≥ 300 μm on SD-OCT. IVR injection was performed at baseline and repeated monthly if CSFT > 300µm. Preoperatively and monthly, ophthalmological examination was performed including measurements of BCVA, CSFT, and macular sensitivity. Results One-year follow-up data is available for 37 eyes of 27 patients. Mean ± SE CSFT (µm) was 509.36 ± 25.14 and 325.76 ± 15.34 at baseline and 12 months, respectively. A significant reduction in mean CSFT was observed at all study visits compared to baseline (p < 0.001). Mean ± SE BCVA (logMAR) was 0.62 ± 0.04 and 0.45 ± 0.04 at baseline and 12 months, respectively. A significant improvement in mean BCVA was observed at all study visits compared to baseline (p < 0.001). Mean ± SE macular sensitivity (dB) was 17.85 ± 0.80 and improved to 19.05 ± 0.59 after one year of follow-up (p = 0.006). The mean number of IVR injections was 8.29 ± 0.63. The mean number of MP laser procedures including the initial SWG laser session was 3.67 ± 0.22. No ocular or systemic adverse effects were observed. Conclusion The SWG laser technique plus IVR was associated with significant improvement in macular edema, BCVA, and macular sensitivity in patients with center-involving DME. Clinical Trial Number (CAAE) 22969019.4.0000.5440.

Keywords

• Diabetic retinopathy
• Diabetic macular edema
• Subthreshold micropulse laser
• Non-damaging retinal laser
• Retinal photocoagulation
• Retinal photostimulation