Answer:
Many type of lasers have been tried on keloids. The continuous-wave
CO2 laser were first reported to give good results by Bailin
in 1982. The laser’s beneficial effect was attributed to its nontraumatic
and anti-inflammatory properties. Later reports by Norris and then Apfelberg
showed that CO2 laser excision failed to suppress their growth
and recurrences. The argon laser was thought to work by coagulation of
the capillary plexus leading to an area of localized anoxia believed to
cause granulocytic lysis and release of collagenase. Studies have failed
to show efficacy with the argon laser. No improvement is seen in patients
longterm. The neodymium-YAG laser results have been mixed, some reports
noting good results but others only with steroid. The mechanism is postulated
to be a selective photobiological effect on collagen metatbolism. Finally
the 585-nm pulsed dye laser has been shown to result in softening and flattening
of scars as well as decreased erythema. The mechanism of improvement in
scar texture produced by this vascular-specific laser has been theorized
to result from decrease microvascular perfusion altering ratio of collagen
metabolism to catabolism, and superheating of collagen fibers dissociates
disulfide bonds which are subsequently reorganized in alignment.