Objective: To evaluate the effects of rejuvenation by intense pulsed light (IPL) and the mechanism thereof.
Methods: Fifty-eight patients with photo aging were treated with IPL of single, double, or triple pulse pattern for 3 - 5 times with the intervals of 3 - 4 weeks. Three weeks after the last treatment, photography was conducted and the pictures underwent grading by the physicians and patients according to blind method. Skin specimens of the posteroinferior ear lobe or the nape were obtained from 4 patients to undergo HE staining, Uana orcein staining of elastin, immunohistochemical staining for collagenous fibers of types I and III, and transmission electron microscopy was conducted in 2 of the 4 patients. Skin digitalized image analysis was conducted on 34 female patients to measure and analyze the depth and width of dermatographs, roughness of skin.
Results: After the third treatment, the wrinkles and skin texture of 62.1% of the patients showed improvement, and 84.60% of the pigmented lesions and 81.25% of the vascular lesions showed improvement. Pathology showed that type I and type III collagen increased while elastin decreased, and the fibers were orderly re-arranged. Transmission electron microscopy showed that after treatment the fibroblasts increased in number and became more active in secretion and there were more collagen fibers orderly re-arranged in the stroma. Digitalized image analysis showed significant improvement in skin smoothness, depth, arithmetic average roughness and average roughness of skin texture (all P < 0.01).
Conclusion: IPL is effective to improve the skin texture. The mechanism may be the increasing of the activity of the fibroblasts, and hyperplasia and re-arrangement of collagen and elastin.