For years doctors have used photo-dynamic light therapy (PDT) to treat various diseases such as brain cancer. PDT uses light-sensitive drugs that produce disease-killing oxygen molecules when activated by a high-intensity light source [source: Alai]. Dermatologists have also used PDT as a treatment for acne, rosacea and skin cancer.
Today, doctors use PDT to activate oxygen molecules in aging skin, which, according to one study, helps skin rejuvenate itself. Researchers at the University of Michigan Medical School in Ann Arbor treated 25 people with PDT. The patients ranged in age from 54 to 83 and all had sun-damaged skin [source: Preidt].
Researchers, led by Dr. Jeffrey S. Orringer, applied a photo-sensitive medication called 5-ALA to the damaged skin. The drug was left on the skin for three hours before it was treated with a laser [source: Preidt]. Over the next six months, researchers took tissue samples of the patients' skin. The samples showed the emergence of high levels of a protein that plays an important role in the growth and development of new skin cells. The skin's outer layer also became thicker [source: Preidt].
Moreover, patients had higher levels of enzymes and other compounds associated with the production of collagen. Doctors said the use of the photosensitive medication in conjunction with the laser created more beneficial changes in skin than laser therapy alone [source: Preidt].
Vicky Wright, a registered nurse in Tennessee, underwent a type of light therapy known as Fractional CO2 Laser Resurfacing. The treatment uses a carbon dioxide laser that delivers thousands of beams of light to bore through the skin's tough outer layer. The light destroyed the old skin cells, while stimulating the body's natural collagen production. The result left Wright with skin that looked fresh and young [sources: Bradley, Bouchez].