The laser transmits a yellow light to destroy the bacteria that causes the acne. It interacts with a substance inside the bacteria called porphorine to create oxygen that destroys the bugs. It also promotes the growth of collagen to prevent scarring.
Several studies have shown it is an effective treatment for acne, but a new trial has questioned these earlier findings. Researchers from the University of Michigan medical school discovered that the laser treatment - known as nonpurpuric pulsed dry laser therapy - failed to treat the condition when it was tested on 40 acne sufferers.
(Source: Journal of the American Medical Association, 2004; 291: 2834-9).