Daylight PDT For Sunspots

  • Best Results1-2 sessions
  • Treatment Recovery3-5 days
  • Procedure TimeVariable
  • Skin SpecialistDr Davin Lim
  • Duration of Results2-5+ years
  • AnaestheticNil required
  • Back to Work2-6 days
  • Cost$$

Daylight PDT For Sunspots

Daylight PDT uses the solar spectrum to activate a chemical called aminolevulinic acid. This chemical is preferentially concentrated in dysplastic or abnormal cells. A chemical reaction with visible light creates a chain reaction that destroys cancerous & precancerous cells. Daylight PDT is equally as effective as LED PDT, however it is much less painful. Laser assisted delivery can improve the outcomes of PDT.

FactsFacts on Daylight PDT

  • PDT is a combination of a photoactive chemical with a light source
  • The blue & red spectrum of light starts the chemical reaction
  • The chemical reaction destroys abnormal & pre-cancerous cells
  • Light delivery can be with a LED device, a laser, or simple daylight
  • Daylight PDT uses the solar spectrum as a natural light source
  • Daylight PDT is as effective as LED illumination
  • Daylight PDT is much less painful than LED illumination

What is daylight PDT?

This form of PDT uses the solar spectrum, namely blue & red light to active chemicals called porphyrins. Porphyrins are selectively concentrated in abnormal skin cells known as solar keratosis.

What type of skin cancer does PDT treat?

PDT is a highly effective treatment for solar keratosis (actinic keratosis), superficial BCCs & in-situ SCCs known as Intraepithelial carcinoma or Bowen disease.

In the context of daylight activation, most dermatologists use this activation method for treating large areas of sun damage, namely solar keratosis. 

How does daylight PDT compare with normal PDT?

Daylight PDT has a similar efficacy of clearing sunspots compared to in-office PDT, namely 70%-90+% efficacy. Daylight PDT has many advantages over traditional PDT, including less pain, & the convenience of doing this procedure at home.

*Some patients may require in-office preparation, especially to hypertrophic or raised/thick areas of solar keratosis.

How to perform daylight PDT?

Application will differ slightly depending on your treating dermatologist. Here is my protocol-

Application area will be described during your consultation. Refer to the photos I have taken on your phone. Pick a time in the morning or in the late afternoon to complete your treatment.

  • Scrub area with gauze provided.
  • Apply Metvix that I have provided to the areas. Thin coat.
  • Sit in the shade (not direct sunlight). Give 2 hours for the chemical to be fully activated.
  • You can take toilet breaks as required.
  • Wash off the remaining Metvix after the procedure.
  • You may be sun sensitive for 48 to 96 hours post PDT.

Your dermatologist may ask you to apply sunscreen pre-treatment. Sunscreen protects against UVB & UVA, & not visible blue & red lights. For my protocol, you do not need to apply sunscreen. Opaque sunscreen with physical blockers may, in some cases reduce visible light transmission via reflectance.

Davin’s viewpoint on daylight PDT

This is my preferred application method of PDT as the scientific literature reflects the efficacy. Laser assistance using fractional resurfacing gives the highest clearance rates – typically over 90% with one treatment. Depending on the severity of sun damage, I may elect to use either a thulium 1927 or fractional CO2.

Laser delivery has several advantages. Firstly, increased absorption of aminolevulinic acid. Studies have shown that the optimal depth of laser penetration is actually very shallow, namely only a fifth of the thickness of epidermis. Hence lasers are used to just penetrate the cornified layer of the stratum corneum. There are many papers pointing out the short contact, laser delivered PDT gives just as good results compared to long contact, dispelling the current trend of long incubation periods.

As with all sunspots treatments, prevention of further solar keratosis post PDT is advisable. The foundation of management is with high factor SPF 50+ sunscreens. High risk patients are followed up by dermatologists who may employ retinoids, either orally or topically. Niacinamide or vitamin B3 at a dose of 500mg twice daily can reduce solar keratosis by as much as 35%.

My most common prescriptions include pulsed 5FU once to twice a week, retinoic acid peels every 2-3 months, or AHA (glycolic acid) in a step up 20-70% routine. Occasionally I get patients to spot apply Metvix to areas of solar dysplasia in between follow ups.

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