A Clinical Study of Hair Removal Using the Long-pulsed Ruby Laser

Abstract

Long-pulsed ruby laser treatment resulted in significant hair growth delay in most cases. Repeated laser treatments produced an increased number of vellus hairs, an increase in growth delay, and a decreased percentage of hair regrowth.

Mathematical modeling for the prediction and optimization of laser hair removal

“…4. Experimental hair regrowth data from sites receiving three ruby laser treatments at 4-week intervals [19] compared with results from the nonstationary model. The closest approximation to the actual results occurred when it was assumed that 50% of the anagen hairs were destroyed per treatment.…”

Long-term Photoepilation Using a Broad-spectrum Intense Pulsed Light Source

“…A 1-cm 2 grid was used to count hairs at baseline and at various subsequent times (including 1, 2, 3, 4,6,8,9,12,14,16,18,20,24, and 30 months after IPL treatment for different patients) as previously described. 27 The data summarize the final clearance results observed at the last follow-up visit, accounting for different follow-up intervals after initial treatment (range, 12-30 months; mean±SD, 21.1±5.1 months).…”

High-Intensity Flashlamp Photoepilation

“…Because of the apparently different responses of hair follicles, some authors 19 proposed that multiple treatments, performed after a delay of several weeks to months, may be more efficacious than a single exposure. In the present flashlamp study, in which subjects were not randomly assigned to 1 or more treatments, overall there were no statistically significant differences in hair counts after a single vs multiple treatments.…”

“…In mice, it has been shown that pigmented anagen hair follicles are more sensitive to ruby laser exposure than are catagen or telogen follicles. 23 Some studies 19 in humans reported that nonpigmented hairs show little or no response to ruby laser exposure.…”

“…Q-switched 1064-nm Nd:YAG laser irradiation has been used to remove hair from mucosae or transplanted skin 11,12 and subsequently was combined with topical application of carbon suspension in an attempt to increase absorption of radiant energy by follicles; however, use of the latter modality has been associated with variable results and high recurrence rates. [13][14][15] Use of free-running pulsed ruby (694-nm) and alexandrite (755-nm) lasers reportedly yields better epilation 8,10,[16][17][18][19] ; transient hyperpigmentation in some darker-skinned subjects has been noted. Most long-pulse devices are theoretically based on the principle of thermokinetic selectivity 20 : The absorbed energy destructively heats larger targets such as hair follicles, whereas smaller structures containing the same chromophore are merely warmed below the threshold for destruction.…”