Controlled studies were eligible if they used a sample size of at least 10 individuals for each tested intervention and compared lasers, light sources or photodynamic therapy with no treatment, other optical treatment or traditional topical acne treatments. Primary review outcomes were inflammatory and non-inflammatory response, patient satisfaction or side effects reported in a controlled manner.
A wide range of optical treatments were used in the included studies, including photodynamic therapy, infrared lasers, broad-spectrum light sources, pulsed dye lasers, intense pulsed light and potassium titanyl phosphate laser. The site of treatment was mostly the face, but effects were also measured on the back. Participants were mostly aged less than 50 years. Severity of acne ranged from mild to severe.
One author checked the titles and abstracts of potential studies for possible relevance and another author checked the identified publications. Any disagreement was resolved by discussion.