Comparison of biophysical properties of skin measured by using non-invasive techniques in the KM mice following 595 nm pulsed dye, 1064 nm Q-switched Nd:YAG and 1320 nm Nd:YAG laser non-ablative rejuvenation

Background: The aim of the study was to compare the changes of the biophysical properties and to objectify the effects of 595 nm pulsed dye, 1064 nm Q-switched Nd:YAG and 1320 nm Nd:YAG lasers non-ablative rejuvenation by non-invasive techniques. Methods: KM mice were used for the study. The 595 nm pulsed dye, 1064 nm Q-switched Nd:YAG and 1320 nm Nd:YAG laser treatments were evaluated with biophysical parameter measurements including skin elasticity, skin color, skin trans-epidermal water loss (TEWL) and skin hydration. Results: All three lasers improved the biophysical properties in the skin of KM mice. In skin elasticity measurements, the 1064 nm laser treatment showed the lowest ratio (0.61 +/- 0.09) while the 1320 nm laser showed the highest one (0.76 +/- 0.07) on day 60. For erythema values, a significant increase was observed immediately after the 1064 nm laser treatment (196.67 +/- 19.17), but the lowest values occurred with the 1320 nm laser treatment (189.83 +/- 16.54). None of the three lasers resulted in obvious changes of skin melanin. TEWL increased immediately after laser irradiation, then began to recover and decreased 60 days after the 595 and 1064 nm laser treatments. With the 1320 nm laser treatment the TEWL began to decrease from day 7 and obtained the lowest mean values (5.23 +/- 1.13). The water-holding capacity increased initially for the 595 and 1320 nm laser irradiation, while decreased for the 1064 nm laser. At day 60 of the experiment, skin hydration values in all animals were superior to those of the controls. The 1320 nm laser treatment caused the highest ratio (1.29 +/- 0.26). Both the values of TEWL and skin hydration for the 1320 nm laser treated areas differed significantly from the other two lasers. Conclusions: Our data showed the 1064 nm Q-switched Nd:YAG laser treatment was most effective in improving the skins' mechanical properties, while the 1320 nm Nd:YAG laser can enhance greatly the skin barrier function and the water-holding capacity. Moreover, we demonstrated the biophysical properties differed considerably between different areas.