What is photodynamic therapy primarily used to treat?

Photodynamic therapy (PDT) is primarily utilized for the treatment of actinic keratosis, which is a precancerous condition characterized by rough, scaly patches on sun-exposed skin. This therapy leverages the use of light-sensitive drugs that are activated by specific wavelengths of light to target and destroy abnormal skin cells associated with actinic keratosis.

The mechanism involves applying a photosensitizing agent to the affected area, followed by exposure to a light source that activates the drug. As the light interacts with the photosensitizer, reactive oxygen species are generated, leading to the destruction of the targeted abnormal cells while minimizing damage to surrounding healthy tissue.

While photodynamic therapy can also have applications in treating other skin conditions, such as acne or certain types of skin cancers, its primary indication is for actinic keratosis, making it the best answer in this context.