Prospective randomised controlled trial comparing sub-threshold micropulse diode laser photocoagulation and conventional green laser for clinically significant diabetic macular oedema

Br J Ophthalmol. 2009 Oct;93(10):1341-4. doi: 10.1136/bjo.2008.146712. Epub 2008 Dec 3.


Aim: The study was a prospective randomised controlled double-masked trial performed in two centres to compare sub-threshold micropulse diode laser photocoagulation (MPDL) with conventional green laser photocoagulation (CGL) in the treatment of clinically significant diabetic macular oedema (CSMO).

Methods: Fifty-three patients (84 eyes) with diabetic CSMO were randomly assigned to MPDL (n = 44) or CGL (n = 40) according to the modified Early Treatment Diabetic Retinopathy Study (ETDRS) protocol. Treatments were performed after baseline and re-treatments were allowed at or after the 4 month visit if necessary. Parameters noted included the best corrected visual acuity (BCVA), colour fundus photographs, central retinal thickness using optical coherence tomography (OCT), vision contrast sensitivity with Pelli-Robson charts and presence of visible laser scars at baseline and at 4 and 12 months. The primary outcome was BCVA at 12 months.

Results: All patients completed 12 months of follow-up after treatment at baseline. There were no statistically significant differences in BCVA, contrast sensitivity and retinal thickness between the two laser modalities at 0, 4 and 12 months. We found that laser scarring was much more apparent with CGL than with the sub-threshold approach (MPDL). Laser scars were identified at the 12 month visits in 13.9% of the MPDL-treated eyes compared with 59.0% of the CGL-treated eyes (p<0.001).

Conclusion: Sub-threshold micropulse diode laser photocoagulation is equally as effective as CGL treatment for CSMO.

Trial registration number: ISTRN 90646644.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Cicatrix / etiology
  • Contrast Sensitivity
  • Diabetic Retinopathy / pathology
  • Diabetic Retinopathy / physiopathology
  • Diabetic Retinopathy / surgery*
  • Double-Blind Method
  • Female
  • Humans
  • Laser Coagulation / adverse effects
  • Laser Coagulation / methods*
  • Macula Lutea / pathology
  • Macular Edema / pathology
  • Macular Edema / physiopathology
  • Macular Edema / surgery*
  • Male
  • Middle Aged
  • Prospective Studies
  • Treatment Outcome
  • Visual Acuity