UNDERSTANDING PHOTODYNAMIC THERAPY (PDT) PDT therapy uses a combination of pure visible Blue, Red or Yellow light to stimulate the deeper skin tissue, whilst being safe to perform on all skin types and conditions. It promotes skin healing, enhances rejuvenation and calms the skin after heat therapies. The different lights target specific cells which are responsible for the synthesis and repair of the skin's supportive structures. It can be had as a stand-alone treatment or combined with various