Alteration of skin temperature during low-level laser irradiation at 830 nm in a mouse model.
OBJECTIVE
This study investigated the change in local skin temperature in black and white mice during irradiation at 830 nm.


BACKGROUND
The photostimulation effect low-level laser therapy (LLLT) (700-900 nm) is widely accepted and used. However, the exact biological mechanisms of biostimulation are not yet established.


METHODS
Groups of C57BL/6J and BALB/cJ mice (n = 12 in each group) were lightly anesthetized with 50% carbon dioxide and 50% oxygen. The dorsum was shaved and a 1.0 x 0.5 cm spot was marked in the same location on each subject. Animals were photo-irradiated with a diode laser (CW, 830 nm, 36 mW output at 5 cm distance). Fluences of 0.0-5.0 J/cm(2) were delivered. Skin surface temperature was monitored by a thermal camera. Two thermocouples were placed 1 mm below the skin surface at the site of light exposure.


RESULTS
Temperature increased with increasing fluences of exposure. The surface temperature change at 5.0 J/cm(2) was 6.25 x 10(-2) +/- 2.0 x 10(-3) vs. 1.2 x 10(-2) +/- 3.0 x 10(-3) degrees C/mW for black and white mice, respectively. The temperature change at 1.0 mm depth was 4.51 x 10(-2) +/- 3.0 x 10(-3) vs. 0.83 x 10(-2) +/- 1.0 x 10(-3), respectively.


CONCLUSIONS
CW irradiation at 830 nm and 5.0 J/cm(2) fluence induces a small temperature increase at the surface and at 1 mm in depth. The smaller effects seen in white mice might be due in part to reflection. This suggests that the thermal effects of irradiation at 830 nm are unlikely to explain the LLLT effect. However skin color should be considered, particularly at higher fluences. Further investigations are warranted to correlate the melanin content of the skin with observed LLLT effects.
The Laser Center, Rochester General Hospital, Rochester, New York 14621-3095, USA. istvan.stadler@viahealth.org
Istvan
I
Stadler
Raymond J
RJ
Lanzafame
Philip
P
Oskoui
Ren-Yu
RY
Zhang
John
J
Coleman
Megan
M
Whittaker
D000818:Animals; D028022:Low-Level Light Therapy / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D012867:Skin / Q000528:radiation effects*; D012881:Skin Temperature / Q000528:radiation effects*