Subthreshold Micropulse Infrared Diode Laser treatment Of Diabetic Macular Oedema – Short Term Results

1. Mark Donaldson^1,2
2. Monika Pradhan^2,1

¹Auckland District Health Board, Auckland, New Zealand
²University of Auckland, Auckland, New Zealand

Purpose:
Current macular laser treatment for diabetic macular oedema (DMO) is associated with visible scarring and reduction in central retinal sensitivity. A subthreshold micopulse protocol using infrared diode laser, that is reported to avoid tissue injury, is being trialed in a public hospital at Auckland. The primary aim is to assess its feasibility for routine use in treatment of DMO.

Methods:
A prospective clinical series is being undertaken. Cases of DMO with best corrected visual acuity (BCVA) better than 6/60 are included. An Iridex 810nm SLX laser with micropulse setting at 5% duty cycle is used. Follow-up period is 12 months. BCVA, clinical examination, ocular coherence tomography (OCT), fundus autofluorescence (FAF) and colour photos are recorded at all visits with baseline and final fluorescein angiography.

Results:
13 eyes of 9 patients are enrolled to date. BCVA is maintained or improved in all. Nine eyes have required three 6-weekly laser sessions. All eyes have reduced mean central retinal thickness except one, which has been withdrawn for intavitreal therapy. No visible whitening during treatment and no scars at follow-up are seen either clinically or on FAF.

Conclusions:
Micropulse laser is a safe and efficacious treatment for DMO but requires multiple treatments according to our current protocol. Laser close to the foveal avascular zone and repeat treatments are enabled due to lack of scarring. Further refinement of treatment protocols will allow its routine use in the public hospital with the significant advantage of avoidance of long-term side effects routinely associated with conventional laser.