Side effects from dermatological laser treatment related to UV exposure and epidermal thickness: a murine experiment with the copper vapor laser.
OBJECTIVE
The intention of the present study was to clarify whether UV-exposure prior to laser treatment of albino mouse skin may influence laser-induced side effects and if a possible influence may be explained by epidermal thickening.


METHODS
Albino, hairless mice were irradiated 0, 8, and 22 consecutive times with simulated solar UV (1.4 J/cm2 per treatment). Subsequently, two areas on the back of the mice (1.26 cm2 each) were treated with a copper vapor laser that was connected to a Hexascan. The beam diameter was 1 mm, pulse duration 200 msec, and intensities 0.6 W, 0.8 W, and 1.0 W. Laser-induced wounds, scars, and histologically evaluated fibrosis were evaluated.


RESULTS
We found that mice irradiated with UV before laser treatment developed smaller wounds, smaller texture change areas, and less fibrosis as compared with nonirradiated control groups, and significant, negative correlations were demonstrated between epidermal thicknesses (stratum corneum, the cellular part of epidermis, and the entire epidermis) and laser-induced skin reactions. A dose response was obtained between laser intensities and laser-induced skin reactions, which tended to be more severe in the cranial back location as compared with the caudal back location. Epidermal layers increased significantly after eight consecutive times of UV irradiation and increased to a steady level after 22 times of irradiation.


CONCLUSIONS
We conclude that UV exposure prior to laser treatment of albino mice reduced laser-induced side-effects, which could be explained by increased epidermal thickening. Variations in epidermal thickness might thus contribute to variations in clinical response to dermatological laser treatment with the copper vapor laser.
Haedersdal
M
M
Department of Dermatology, Copenhagen University Hospital, Bispebjerg Hospital, Denmark.
Therkildsen
P
P
Bech-Thomsen
N
N
Poulsen
T
T
Wulf
H C
HC
D000818:Animals; D002921:Cicatrix / Q000473:pathology; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007834:Lasers / Q000009:adverse effects*; D051379:Mice; D008812:Mice, Hairless; D011833:Radiation Injuries, Experimental / Q000473:pathology; D012867:Skin / Q000473:pathology / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*