Topical ALA and Blue Light

Starting in the 1990s, blue light was extensively studied for the treatment of AK due to the superficial localization of these precancerous lesions. The combination of topical ALA for 14-18-hour incubation followed by 1000 seconds of blue light illumination achieved FDA approval for the treatment of AK in 1997 [40]. The Phase III trial, which was random­ized, placebo-controlled, and investigator-blinded, demonstrated that 89% of patients achieved greater than 75% clearing of AK at 12 weeks following one to two treatments [41]. Short 1-hour incubation topical ALA followed by blue light has since been demon­strated to be effective in treating diffuse photodamage [42]. The advantages of this approach is the FDA-approved status of the application for AK, which often coexists with photoag­ing; however the disadvantages include side effects, such as crusting, and up to several weeks of recovery time.