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  • Dr. Henry Ngai

Photodynamic therapy (PDT)


There are a sizeable portion of people who do not have a good response to the conventional acne treatment. Many experiences unpleasant side effects from topical or oral medications which limit the use these products. Photodynamic therapy or PDT, an excellent adjunctive acne treatment, is safe, effective and has a very low side effect profile. It also has the extra benefit of skin rejuvenation as well as good improvement of red and dark acne scars.


What is PDT?


Photodynamic therapy (PDT) uses medications called photosensitizers to boost the activity of a light-based skin treatment. The usual agents used are 5-ALA (5- alpha aminolaevulinic acid) or MLA (methyl-ester of ALA). The agents are applied on the skin and was let sit for certain length of time for the skin to absorb the products. These photosensitizes are preferably taken up by the more metabolic active cells such as sebaceous/ oil glands, as well as precancerous or cancerous cells. After this, the skin is irradiated with a light such a blue/ red light or similar light source. The photosensitizer generates reactive oxygen species (ROS) which are free radicals and are inherently unstable chemically. ROS have to return to a reduced state but during the process causing a number of events in the skin. The mechanism of rejuvenation and skin change is caused by growth factor (TGT-β and FGF) production accelerating fibroblast activation and synthesis of new collagen (type l- lll). Photodynamic therapy also reduces the size and activity of the oil-producing sebaceous glands. Overactivity and inflammation of these glands contribute to acne development.


What do you expect to see after PDT?


You should see a reduction of inflammatory acne lesions as well as a reduction in sebaceous activity. There will be improvement in skin elasticity, texture, wrinkling and overall skin quality.


What is the procedure of PDT like?


The entire procedure takes about 1.75 hours. Your skin is prepped by microdermabrasion. The photosensitizer product is then applied o your skin for 40-45 min which the followed by exposure to a light source. A cooling mask is applied to the face at the end.

The procedure is painless. Some people will experience minor tingling sensation of the skin. Some degree of redness might persist for a few hours afterwards.


What is the post-treatment care?


Ongoing sunscreen use and avoidance of direct sun exposure for 24 -48 hours are advisable. Mild cleanser is to be used on the face and you may use a water based non-comedogenic moisturizer as needed. Otherwise, you can pretty much resume your usual activities the very next day, including work and sport activities.


It would be prudent not to undergo any cosmetic procedure the week after PDT as the skin might be more sensitive than before. You should consult with us beforehand.


Reviva PDT protocol


At Reviva Laser Skin Clinic, we choose an non ALA-based photosensitizer which is much less likely to produce prolonged redness and skin irritation. The product is activated much faster to the light source and therefore a shorter period of time of sun avoidance post treatment. It has a higher safety profile than the traditional PDT procedure.