Hair removal with an 800-nm pulsed diode laser.

BACKGROUND AND OBJECTIVE: Laser hair removal is a relatively new procedure. Our purpose was to study the efficacy and safety of a high-power, pulsed diode laser array for removing unwanted hair. METHODS: A total of 38 subjects were treated with a prototype of the 800-nm diode laser system. Fluences ranging from 10 to 40 J/cm(2) (mean, 33.4 J/cm(2)) were used and 1 to 4 treatments (mean, 2.7) were performed. Evaluation of hair loss was performed at least 4 months after the last treatment (mean, 8.7 months) by a blinded assessment of clinical photographs. RESULTS: A total of 59% of the subjects had only sparse hair regrowth at the final follow-up. Higher fluences and multiple treatments produced greater long-term efficacy. Transient pigmentary changes occurred in 29% of the subjects and were more common in darker skin types IV to VI (P =. 047). CONCLUSION: The 800-nm diode laser is an efficient and safe technique for hair reduction. Adverse pigmentary effects occur, but are transient.

Reduction of regrowing hair shaft size and pigmentation after ruby and diode laser treatment.

Laser pulses which selectively damage pigmented hair follicles are a useful treatment for hypertrichosis. Clinically, regrowing hairs are often thinner and lighter after treatment. In this study, hair shaft diameter and optical transmission (700 nm) were measured before and after ruby (694 nm) and diode (800 nm) laser irradiation. Hair was collected from 47 and 41 subjects treated with ruby (0.3 ms and 3 ms) and diode (10-20 ms) lasers, respectively. "Responders" were defined as subjects with significant long-term hair loss as determined by hair counts at 9 and/or 12 months after treatment. In ruby laser responders (34/47), regrowing hairs were significantly both thinner (decreased diameter) and lighter (increased transmission). In "nonresponders" (13/47), regrowing hairs were lighter, but not thinner. The regrowing hair shaft absorption coefficient (as calculated assuming Beer's law) was significantly decreased by 0.3 ms ruby laser treatment, but was not changed by 3 ms ruby laser or diode laser treatment. After diode laser treatment, 38 of the 41 subjects were responders and regrowing hairs were both thinner and lighter. These results show that laser treatments can affect structural recovery (size of hair), follicular pigmentation (hair absorption coefficient), or both. Regrowth of thinner hair (decreased shaft diameter) occurs in conjunction with actual loss of hair. After long pulses (3 ms ruby; diode), regrowing hair was thinner and also lighter to an extent related to the decrease in hair diameter. In contrast, short ruby laser pulses (0.3 ms) appeared to be capable of inhibiting follicular pigmentation per se, in addition to affecting the hair diameter. This may account for the complete regrowth of lighter hair in "nonresponders" treated with 0.3 ms pulses. Laser-induced reduction in hair diameter and/or pigmentation are both long-term responses which confer cosmetic benefits in addition to actual hair loss.

Ruby laser hair removal: evaluation of long-term efficacy and side effects.

BACKGROUND AND OBJECTIVE: Although several studies on laser-assisted hair removal have been published, data on long-term follow-up are few. The present study investigated the long-term efficacy and safety of normal-mode ruby laser pulses on hair removal. STUDY DESIGN/MATERIALS AND METHODS: The normal-mode ruby laser (Epilaser; 694 nm, 3 msec) was used to treat a wide range of body sites in 51 volunteers. The mean follow-up after the last treatment was 8.37 months. RESULTS: Sixty-three percent of the patients had sparse regrowth. The mean fluence used was 46.5 J/cm(2) in patients who had sparse hair regrowth and 39.3 J/cm(2) in patients who had moderate hair regrowth (P = 0.0127). Transient pigmentary changes occurred most frequently in patients with skin type 4. CONCLUSION: The normal-mode ruby laser is an efficient and safe method for long-term hair reduction, especially in fair-skinned individuals with dark hair. Higher fluences produce greater long-term efficacy. Adverse effects are minimal and transient.

Hair removal by lasers and intense pulsed light sources.

Unwanted pigmented hair is a common problem for many patients. Traditional methods of hair removal have included shaving, bleaching, plucking, waxing, use of chemical depilatories, and electrolysis. These techniques have been limited by their pain, inconvenience, and poor long-term efficacy. Only electrolysis has offered the potential for permanent hair removal. However, the technique is tedious, highly operator-dependent, and impractical for the treatment of large numbers of hairs. Recently, a number of lasers and other light sources have been developed specifically to target hair follicles. These include ruby, alexandrite, diode, and Nd:YAG lasers and an intense pulsed light source. These devices offer the potential for rapid treatment of large areas and long-lasting hair removal. This article explains the mechanisms of using light to remove hair, examines the attributes of specific laser systems, and explains the importance of patient selection and treatment protocol for the various systems in order to provide a safe and effective treatment.

Laser hair removal affects sebaceous glands and sebum excretion: a pilot study.

BACKGROUND: During laser-assisted hair removal, sebaceous glands closely associated with hair follicles might also be affected. OBJECTIVE: We investigated the effect of the long-pulsed ruby laser on sebaceous glands. METHODS: Sebum excretion rates (SERs) of 16 subjects were measured quantitatively by means of sebum-absorbent tape and analyzed by means of image analysis techniques on laser-treated sites, compared with adjacent untreated areas. Evaluation was done at an average of 9 months (range, 4.5 to 12 months) after the last treatment. Histologic examinations were performed on 3 representative subjects before treatment, immediately after treatment, and 9 months after the last treatment. RESULTS: Significant increases in SERs were observed in 11 of 16 subjects (68.75%). Three subjects (18.75%) showed lower SERs, whereas 2 subjects (12.5%) demonstrated no difference in SERs between treated and untreated areas. Biopsy specimens showed an apparent reduction in sebaceous gland size. Specimens taken immediately after laser irradiation revealed sporadic damage to sebaceous glands. CONCLUSION: In some patients a variable but statistically significant increase in sebum excretion occurs 4 to 12 months after ruby-laser hair removal treatment at high fluences. A reduction in sebaceous gland sizes on laser-treated areas was observed. We hypothesize that decreased resistance to sebum outflow may explain this result, following miniaturization or absence of hair shaft after ruby laser treatment. Further study is needed to assess mechanisms for this interesting response.

Permanent hair removal by normal-mode ruby laser.

OBJECTIVE: To assess the permanence of hair removal by normal-mode ruby laser treatment. METHODS: Hair removal was measured for 2 years after a single treatment with normal-mode ruby laser pulses (694 nm, 270 microseconds, 6-mm beam diameter). OBSERVATIONS: Six test areas on the thighs or backs of 13 volunteers were exposed to normal-mode ruby laser pulses at fluences of 30 to 60 J/cm2 delivered to both shaved and wax-epilated skin. In addition, there was a shaved and wax-epilated control site. Terminal hairs were manually counted before and after laser exposure. Transient alopecia occurred in all 13 participants after laser exposure, consistent with induction of telogen. Two years after laser exposure, 4 participants still had obvious, significant hair loss at all laser-treated sites compared with the unexposed shaved and wax-epilated control sites. In all 4 participants, there was no significant change in hair counts 6 months, 1 year, and 2 years after laser exposure. Laser-induced alopecia correlated histologically with miniaturized, velluslike hair follicles. No scarring and no permanent pigmentary changes were observed. CONCLUSIONS: Permanent, nonscarring alopecia can be induced by a single treatment with high-fluence ruby laser pulses. Miniaturization of the terminal hair follicles seems to account for this response.

Hair growth cycle affects hair follicle destruction by ruby laser pulses.

It has been shown that normal mode ruby laser pulses (694 nm) are effective in selectively destroying brown or black pigmented hair follicles in adult Caucasians. This study investigated how the various stages of the hair follicle growth cycle influence follicle destruction by ruby laser treatment, using a model of predictable synchronous hair growth cycles in the infantile and adolescent mice. A range of ruby laser pulse fluences was delivered during different stages of the hair growth cycle, followed by histologic and gross observations of the injury and regrowth of hair. Actively growing and pigmented anagen stage hair follicles were sensitive to hair removal by normal mode ruby laser exposure, whereas catagen and telogen stage hair follicles were resistant to laser irradiation. Selective thermal injury to follicles was observed histologically, and hair regrowth was fluence dependent. In animals exposed during anagen, intermediate fluences induced nonscarring alopecia, whereas high fluences induced scarring alopecia. The findings of this study suggest treatment strategies for optimal laser hair removal.

Thermal relaxation of port-wine stain vessels probed in vivo: the need for 1-10-millisecond laser pulse treatment.

Although thermal relaxation times of cutaneous port-wine stain microvessels have been calculated and used to formulate laser selective photothermolysis, they have never been measured. A scheme to do so was devised by measuring the skin response to pairs of 585-nm dye laser pulses (250-360 microseconds each) as a function of the time interval between the two pulses, in five volunteers with port-wine stains. After a pump pulse delivering 80% of the fluence necessary for causing purpura, the fluence of a second probe pulse necessary to cause purpura was determined and was found to increase with the interval between the two pulses, in a manner consistent with thermal diffusion theory. Biopsy specimens were obtained from four of the five subjects to examine the nature and extent of vessel damage and to measure the port-wine stain vessel diameters. Using diffusion theory, the thermal relaxation time was calculated based on the measured vessel diameters. These calculated values are consistent with the increase in radiant exposure (fluence) of the probe pulse necessary to induce purpura for longer time delays. Two simple models for thermal relaxation of port-wine stain vessels are presented and compared with the data. The data and histologic assessment of the vessel injury strongly suggest that pulse durations for ideal laser treatment are in the 1-10-millisecond region and depend on vessel diameter. No dermatologic lasers presently used for port-wine stain treatment operate in this pulse width domain.