Subthreshold Diode Micropulse Laser: A Review

Abstract

The subthreshold diode micropulse laser is a form of non-damaging thermal laser therapy which has shown efficacy in multiple retinal conditions. The purpose of this article is to review the use of subthreshold diode micropulse laser as an emerging treatment modality for the treatment of retinal disease. The proposed mechanisms of action, safety, efficacy, recommended laser treatment parameters, and clinical applications for which the use of subthreshold diode micropulse laser has been studied will be reviewed.

Efficacy and safety of subthreshold micropulse laser compared with threshold conventional laser in central serous chorioretinopathy

“…Unlike conventional laser, a subthreshold micropulse laser (SML) is non-damaging, the para-fovea or fovea can be directly treated, and treatment can be repeated without detectable structural or functional damage [13]. SML involves a series of repetitive laser pulses with an interval.…”

“…SML involves a series of repetitive laser pulses with an interval. SML have been used in the treatment of a wide range of retinal disease in clinical studies and are commercially available and FDA approved [13], meaning that SML can be considered as an alternative treatment for CSC.…”

Innovations in Retinal Laser Technology

“…A duty cycle is the fraction of a period of time when the laser is "on". This "on" time is the duration of each micropulse (typically 100 μs to 300 μs), and the "off" time (typically 1700 μs to 1900 μs) is the interval between micropulses, which allows for reduction of originated heat [30]. When a low duty cycle is used, commonly set at 5% for SDM, the "on" time is short enough to allow the tissue return to baseline temperature between pulses, which also limits the time for thermal dissipation between each pulse thereby reducing collateral damage.…”

Review of Subthreshold Diode Micropulse Laser Treatment for Retinal Diseases

“…Although it still remains unclear, there have been numerous theories for the therapeutic effect of conventional retinal photocoagulation. It is postulated that laserinduced retinal destruction reduces the metabolic demand of a hypoxic retina by 1) targeting metabolically active photoreceptors, 2) increasing choroidal retinal oxygenation, 3) upregulating heat-shock proteins (HSPs), and/or 4) altering vasoactive cytokines including VEGF [4,11,13,14]. In particular, focal retinal laser is thought to photocoagulate microaneurysms and lessen macular edema [6,14].…”