Numbing Agents Cause More Pain in PDT

The fractional laser–pretreated areas also displayed significantly greater improvement in photoaging and fewer new AKs at follow-up: 3, compared with 11. But these superior outcomes came at a price: higher pain scores during illumination and significantly worse erythema and crusting post treatment (Br. J. Dermatol. 2012 Feb. 20 [doi:10.1111/j.1365-2133.2012.10893.x]).

Fractional CO₂ laser pretreatment enhances conversion of the photosensitizing agent to protoporphyrin 9, Dr. Ross explained. He compared the tiny holes in the skin created by the fractional laser to the process of aerating a lawn. The holes create conduits for the photosensitizer to bypass the stratum corneum, which is the major obstacle to uptake of ALA or MAL. Once the photosensitizer skips past the stratum corneum, it quickly spreads laterally throughout the epidermis.

However, Dr. Ross offered a note of caution regarding this novel approach. He said that he performed the therapy recently and found that 30 minutes of ALA incubation was too much.

"If you do these procedures, I would say go very light and just leave the ALA for less than 30 minutes to start, because the response you’re going to get when using a fractional laser beforehand is profound. It’s a huge difference," he said.

Dr. Ross reported that he serves as a consultant to and receives research support from Palomar. He also disclosed receiving research support from Candela, Cutera, Lumenis, Sciton, and Ulthera.

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