Response to subthreshold micropulse laser treatment in the prophylaxis of diabetic macular oedema: A preliminary...

To evaluate the use of subthreshold micropulse laser (SMPL) in the prevention and management of mild diabetic macular oedema (DME).

This prospective, randomised and sham-controlled study included 159 eyes (123 patients) with diabetic retinopathy, central retinal thickness (CRT) ≤ 325 μm, and best-corrected visual acuity (BCVA) ≥ 80 ETDRS letters. The participants were assigned to either SMPL treatment (n = 103) or sham therapy (n = 56). Ophthalmic evaluations were performed at baseline (T1), 3 months (T2) and 12 months (T3) to assess BCVA and optical coherent tomography (OCT) parameters, including CRT, macular thickness (MT), macular volume (MV), and hyperreflective spots (HRS).

In the SMPL group, BCVA improved after 3 months (T2 > T1; p = 0.002); MT decreased after 12 months (T2, T1 > T3; p < 0.001); MV decreased after 12 months (T2, T1 > T3; p < 0.001); HRS count decreased after 3 and 12 months (T1 > T2, T3, p < 0.001). The decrease in CRT after 3 months was greater in the SMPL group (p = 0.003). The need for rescue therapy was lower in the SMPL group (9.7% vs. 19.6%, p = 0.007). BCVA, CRT, MV, MT and HRS remained stable in the sham group, while microaneurysms count was stable in both groups.

SMPL is safe and effective for the prophylaxis of mild DME, as it reduces MT and MV while keeping BCVA stable. The decreased need for rescue anti-vascular endothelial growth factor therapy suggests that it may delay or reduce intravitreal injections.