Photobiomodulation does not show benefit for treating diabetic macular edema

The Diabetic Retinopathy Clinical Research Network’s (DRCR) Protocol AE examined whether there was a benefit of photobiomodulation (PBM) for diabetic macular edema patients with good vision.

Study design

This was a multicenter phase 2 randomized clinical trial. One eye of patients with center-involved diabetic macular edema (CI-DME) and visual acuity (VA) 20/25 or better were randomly assigned to receive 90-second treatments twice daily for 4 months of either a 670-nm light-emitting PBM eye patch or placebo, an identical device emitting broad-spectrum white light at low power. The primary endpoint was change in central subfield thickness (CST) on OCT at 4 months.

Outcomes

Sixty-nine patients were assigned to PBM and 66 to placebo. There were no differences in the mean CST, VA, or proportion of eyes with CI-DME between the PBM or placebo groups. From baseline to 4 months, the average CST increased by 13 (SD: 53) μm in PBM eyes and 15 (SD: 57) μm in placebo eyes. Sixty-one (90%) PBM eyes and 57 (86%) placebo eyes had CI-DME after 4 months. The mean VA decrease was −0.2 (SD: 5.5) letters in the PBM group and −0.6 (SD 4.6) letters in the placebo group. There were no serious adverse events in either group.

Limitations

It is not known if different treatment algorithms with PBM (e.g., duration of treatment, frequency of treatment, or different wavelengths) might provide a benefit.

Clinical significance

PBM at the settings of the DRCR’s Protocol AE was not effective for patients with CI-DME who have good vision, and did not lead to any serious adverse events.