DAMAGE TO HAIR-FOLLICLES BY NORMAL-MODE RUBY-LASER PULSES

Background: Although many temporary treatments exist for hirsutism and hypertrichosis, a practical and permanent hair removal treatment is n eeded. Objective: Our purpose was to study the use of normal-mode ruby laser pulses (694 nm, 270 mu sec, 6 mm beam diameter) for hair follic le destruction by selective photothermolysis. Methods: Histologically assessed damage in ex vivo black-haired dog skin after the use of diff erent laser fluences was used to design a human study; 13 volunteers w ith brown or black hair were exposed to normal-mode ruby laser pulses at fluences of 30 to 60 J/cm(2), delivered to both shaved and wax-epil ated skin sites. An optical delivery device designed to maximize light delivery to the reticular dermis was used. Hair regrowth was assessed at 1, 3, and 6 months after exposure by counting terminal hairs. Resu lts: Fluence-dependent selective thermal injury to follicles was obser ved histologically. There was a significant delay in hair growth in al l subjects at all laser-treated sites compared with the unexposed shav en and epilated control sites. At 6 months, there was significant hair loss only in the areas shaved before treatment at the highest fluence . At 6 months, four subjects had less than 50%, regrowth, two of whom showed no change between 3 and 6 months. Transient pigmentary changes were observed; there was no securing. Conclusion: Selective phototherm olysis of hair follicles with the normal-mode ruby laser produces a gr owth delay consistent with induction of prolonged telogen with apparen tly permanent hair removal in some cases.