Single retinal layer changes after subthreshold micropulse yellow laser in diabetic macular edema

A pilot prospective, interventional study has been conducted on 10 patients with diabetic macular edema (DME) treated with subthreshold micropulse laser (SMPL) to evaluate changes of individual retinal layers and to correlate with functional changes. All patients underwent complete ophthalmologic evaluation including spectral-domain optical coherence tomography (OCT) and microperimetry at baseline, 3 months, 6 months, 9 months, and 12 months. Compared with baseline, a significant decrease was found in inner nuclear layer (INL) and outer retinal layer (ORL) thickness in the central 1 mm (P < .05). Increase in best-corrected visual acuity was significantly and inversely correlated to central retinal thickness (CRT) (P = .0027), INL (P = .0167), and outer nuclear layer (ONL) thickness (P = .0107). Increase in retinal sensitivity was significantly and inversely correlated to CRT and ONL thickness (P < .01). Therefore, SMPL showed to improve firstly functional parameters and then morphologic parameters. Functional parameters were inversely correlated to CRT, INL, and ONL thickness. The exact mechanism of reduction of INL thickness induced by SMPL remains to be further evaluated.