Abstract
A Q-switched alexandrite laser was used at wavelength of 755nm, a pulse duration of 100ns and a spot size of 3mm. The laser was operated at a repetition rate of 1Hz with an energy fluence of 4.5-8J/cm2. The Q-switched alexandrite laser irradiation is widely used for benign cutaneous pigmented lesions and tattoos. The Q-switched alexandrite laser can remove nevus of Ota, tattoos, traumatic tattoos, senile pigmentations and seborrheic keratosis with a minimal number of treatment and without significant side-effects.
Using light and electron microscopes, we investigated the alterations in melanocytes and recovery of injured tissue of the nevus of Ota by Q-switched alexandrite laser irradiation. Q-switched alexandrite laser is highly selective and highly absorbed by melanosomes. Other cells and tissue components of the dermis remained almost intact. Following irradiation macrophages infiltrated the irradiated areas and scavenged degenerated melanosomes and cellular debris. Thus, discoloration of the skin was markedly reduced.
