Subthreshold micropulse laser (SML) may offer a noninferior treatment alternative to standard laser (SL) for patients with diabetic macular edema (DME) with a central retinal thickness (CRT) of 300–400 μm.
Study design
This was a multicenter, allocation-concealed, patient- and assessor-masked, randomized, noninferiority trial comparing the results of SML to SL therapy in patients with diabetic macular edema (DME) who were deemed amenable to laser treatment by the treating ophthalmologist and had a CRT of >300 μm but <400 μm in the central subfield. Two hundred sixty-six participants were recruited and randomized to receive either SML or SL treatment. Primary outcome data was available for 231 participants (116 in the SML group, 115 in the SL group). Laser retreatments were permitted in either group using the same laser technology the patient initially received, and rescue treatments with anti-VEGF agents or steroids were performed if any patient’s CRT increased to ≥400 μm during follow-up or if a DME-related loss of ≥10 ETDRS letters occurred.
Outcomes
The study found that SML was noninferior to SL for treating DME in patients with CRT of >300 μm but <400 μm in the central subfield. There were no significant differences between the two groups in CRT, 10‑2 Humphrey visual field mean deviation, percentage meeting driving standards, side effects, or the number of rescue treatments. Of note, there was a similar need for anti-vascular endothelial growth factor rescue treatment: 18% in the SML group and 21% in the SL group (P = 0.59). However, the number of laser treatments performed was slightly higher in the SML group (mean difference = 0.48, P = 0.002).
Limitations
The treating physician was not masked to the treatment, and there was no treatment arm assessing anti-VEGF treatment compared to the 2 laser modalities.
Clinical significance
The results of this study suggest that SML is a noninferior alternative to traditional laser therapy in patients with DME and a CRT of >300 μm but <400 μm who are candidates for laser treatment, with clinically similar outcomes.
Dr. Ajay Kuriyan discloses financial relationships with Adverum, Annexon, National Eye Institute (Grant Support); Alimera Sciences, Allergan, Bausch + Lomb, EyePoint Pharmaceuticals, Novartis, Alcon Pharmaceuticals (Consultant/Advisor); Genentech (Consultant/Advisor, Grant Support); Lumata Health (Consultant/Advisor, Private Equity/Stock Holder); Optos, Spark Therapeutics (Lecture Fees/Speakers Bureau); Recens Medical (Consultant/Advisor, Private Equity/Stock Holder).