Does subthreshold micropulse laser provide better outcomes in diabetic macular edema treatment?

UK: Subthreshold micropulse laser (SML) was similar to standard laser (SL) in binocular best-corrected visual acuity (BCVA), says an article published in Ophthalmology.

One prominent reason for diabetic retinopathy vision loss is diabetic macular edema (DME). Although anti-VEGF injections are increasingly employed, particularly in severe instances or those affecting the fovea, where laser treatment is impractical, DME has traditionally been treated with macular laser. Smaller pulses are used in subthreshold micropulse lasers, which, unlike conventional lasers, do not damage the surrounding photoreceptors or the local retinal pigment epithelium. Noemi Lois and colleagues conducted this study in order to assess the clinical efficacy, safety, and economic efficiency of subthreshold micropulse laser therapy compared to regular laser therapy for diabetic macular edema with a central retinal thickness (CRT) >400.

This was a multicenter, pragmatic, allocation-concealed, randomized, double-masked, non-inferiority experiment in which persons with 400 center-involved DME and BCVA >24 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in one/both eyes participated. Retreatments were permitted after a 1:1 randomization to 577nm SML or SL. If there was >10 ETDRS-letter loss and/or CRT rose >400, rescue with intravitreal anti-VEGF treatments or steroids was allowed.

The key findings of this study:

1. DIAMONDS recruited all participants (n=266), with primary outcome data available in 87% of SML and 86% of SL.

2. In SML and SL, the mean BCVA decrease from baseline to month-24 was -2.43 and -0.45, respectively.

3. SML was found not only non-inferior but also equivalent to SL since the 95% CI fell entirely inside both the upper and lower boundaries of the allowable maximum difference (5 ETDRS-letters).

4. Binocular BCVA, CRT, MD, satisfying driving standards, side effects, rescue therapies, or EQ-5D/VFQ-25/VisQoL scores did not vary significantly.

5. SML had a larger number of laser sessions.

6. There were no changes in costs or QALYs based on the base-case study.

In conclusion, the Authors found this study to provide additional data in supporting Subthreshold micropulse laser therapy as a first-line treatment for non-severe Diabetic Macular Edema affecting the central retinal thickness.

Reference: 

Lois, N., Campbell, C., Waugh, N., Azuara-Blanco, A., Maredza, M., Mistry, H., McAuley, D., Acharya, N., Aslam, T. M., Bailey, C., Chong, V., Downey, L., Eleftheriadis, H., Fatum, S., … Clarke, M. (2022). DIAbetic Macular Oedema aNd Diode Subthreshold micropulse laser (DIAMONDS): A randomized double-masked non-inferiority clinical trial. In Ophthalmology. Elsevier BV. https://doi.org/10.1016/j.ophtha.2022.08.012