Laser treatments for PFB including the use of ruby, alexandrite, 800 nm diode and 1080 nm Nd:YAG with and without exogenous chromophores have been evaluated at an increasing rate over the last ten years. The initial rationale for laser treatments for PFB was based on the simple assumption that lasers could achieve a rapid permanent inhibition and/ or modification of hair-shaft growth, which would remove the ingrown hair causing PFB. Most laser treatments are designed to inhibit hair growth by acting on endogenous melanin in the hair follicle and hair shaft, which generates heat when irradiated by laser light. The heat is transferred to the follicle targets in proliferative bulb and keratinization zone regions with the objective of destroying or sufficiently damaging the follicle to achieve a severe inhibition or elimination of hair growth, as well as modification of hair shaft formation from damaged follicles, which would result in a weakened shaft incapable of penetrating the skin. The major issues with using endogenous melanin as the target chromophore for inhibition and/or modification of hair-shaft growth are related to the damage of nonfollicle structures such as epidermal melanocytes, resulting in a variety of pigmentation disorders as well as epidermal damage in the skin of African American subjects. Further, repeated laser treatments are necessary to provide the maximal degree of hair-growth elimination or hair modification. Recent evidence-based reviews on the efficacy and safety of hair-growth inhibition by lasers have led to the conclusion that the effects of lasers on hair-growth inhibition or hair-growth retardation require repeated treatments, and there is no evidence for either complete or permanent hair removal [13]. On the other hand, studies on improvement in PFB by laser treatments indicate that complete or permanent hair removal is not necessary to achieve a significant reduction in lesions. Indeed, highly effective improvements in lesion reductions can be achieved with rather modest reductions in hair growth, and the onset of improvements in PFB can be noticed well before maximal hair growth inhibition effects are noted. Adrian and Shay [14] assessed laser treatments for PFB using the 800 nm diode laser, and most patients noted a reduction in PFB symptoms within two to four weeks of an initial laser treatment, regardless of overall hair reduction success [14]. Another study employed the 800 nm diode laser at low pulse settings (10J/cm2 with pulse width of long duration 30 ms) and patients had significant decrease in ingrown hair after just one session in which hair growth was only diminished by 10-25 %; after 7-10 treatments, the PFB condition was fully resolved [15]. A study by Rogers and Glaser [16] employed the combination of a Q – switched 1080 nm Nd:YAG laser in combination with a topical carbon suspension which penetrated into the follicle orifice surrounding the hair follicle. When the carbon suspension acting as the laser chromophore is irradiated by light, the heat generated is transferred to the follicle structures that support the growth and differentiation of hair shaft resulting in modification of hair growth, and therefore a decreased opportunity for hair to enter the skin and cause inflammatory lesions. The major benefit of this strategy was to minimize the risk for collateral epidermal damage, which, in darker skin is highly pigmented and sensitive to heat transfer. Results proved encouraging as significant reductions in PFB were achieved with benefits persisting at least two months after the two treatments.
In summary, the initial studies on treatment of PFB with lasers are encouraging, as the energy threshold requirements to achieve substantial benefits for PFB were less than required for hair growth inhibition, and this indicated that the treatment of PFB with lasers could be managed with less dermal risks than those associated with hair-growth management. Nonetheless, maintenance of PFB improvements by the laser requires repeated treatments which pose problems for subjects with Type V and Type VI skin as the high melanin content in epidermis poses risks of pigmentation changes. The biggest challenge with laser – mediated hair management is not efficacy, but rather issues related to safety, and since the fluence threshold for resolving PFB appears to be less than that required for the inhibition hair growth, this presents an opportunity for PFB treatment.
The recommendations of Battle and Hobbs [17,18] for safer hair removal by the use of laser in darker skin types apply to laser treatment of PFB. Their recommendations are based on the use of long pulse durations to allow more opportunity to cool the skin, as heat in the epidermis is more easily dissipated by concurrent cooling when the heat is generated at a slow rate with longer pulse lengths. Both longer pulsed 800nm diode and 1064 nm Nd:YAG lasers deliver slower heating, and the suggested pulse lengths with the 800nm diode are greater than 100ms and for the Nd:YAG, the pulse lengths should exceed 30ms. A particular advantage for Nd:YAG is the longer wavelength, which enables epidermal sparring as result of bypassing the epidermal layer and focusing more heat generation in the lower dermal regions of the follicle where cell proliferation and early hair-shaft differentiation is initiated. With the diode laser, pulse widths above 400ms should be avoided, as too long a pulse width increases the opportunity for overheating due to excessive thermal transfer in regions of high follicle density, as well as preventing retrograde damage to epidermis as a result of thermal transfer from dermis to epidermis with excessively long pulse widths. The Nd:YAG is always the treatment of choice in subjects with Type VI skin. With either laser system, lower fluences are recommended for facial treatments as increased hair density in the beard area further increases the risks of thermal transfer between follicles.
The 1064 nm Nd:YAG laser theoretically provides the safest wavelength for treatments in dark skin Types IV-VI. Galadari [19] compared hair-removal efficacy and the safety of alexandrite, diode, and Nd;YAG lasers in these skin types. Results demonstrated similar degrees of hair-removal efficacy between the devices, but the fewest incidence of side effects was with the Nd:YAG laser, providing the conclusion that Nd:YAG allows higher fluences without epidermal damage and maximal benefits in targeting the zones related to hair inhibition in the dermis. In addition to maximizing safety, longer pulse durations maximize efficacy according to the concept of thermal damage time [20], which suggests that increased pulse duration maximizes the diffusion of heat generated in the melanized regions of the hair shaft and bulb to the surrounding follicle structures supporting hair-growth cycling and hair-shaft differentiation. Overall, the results of studies evaluating consecutive treatments with the long-pulsed Nd:YAG laser treatment indicate that it represents a safe and effective option for reducing papule formation in patients with PFB barbae, with results lasting up to two to three months after completion of successive treatments in patients with skin Types IV-VI [21-23]. On the other hand, the use of modified superlong pulse 810 nm diode lasers provided long-lasting lesion reductions after successive treatments, but its use is restricted to patients with Type IV and V skin as patients with Type VI skin experienced unacceptable side effects [24].
A prototype 980 nm laser for self-treatment has been tested for PFB, and the results reported at the 25th annual meeting of the American Society for Laser Medicine and Surgery Orlando 2005 are encouraging [25]. The device provided approximately 3-10 J/cm2. Subjects were treated over a 2-week period receiving 10 treatments. There was a 69% average reduction in the number of lesions, the range being 48-80% at the end of the treatment period. The majority of subjects indicated improvement in shaving bumps, and said there was greater ease of shaving after three to five treatments. The device was designed to retard hair growth and facilitate shaving, and results confirm the viability of a hair-growth retardation strategy in treating PFB.
A variety of treatment options exist for managing PFB, and a judicious use of a combination of treatment options may offer the best opportunity for controlling the formation of ingrown hair that result in shaving bumps and inflammation. The magnitude of improvement resulting from compliance with a daily shaving regimen to provide a very safe, effective, economical, and convenient method to manage PFB can, in some subjects, equal that of professional lasers. The use of appropriate topical treatments such as glycolic acid may enhance the ability to comply with daily shaving, as well alter superficial skin topography to minimize the occurrence of ingrown hair and maximize shaving efficiency. Topically applied hair – growth retardants such as Eflornithine HCl have been demonstrated to slow hair growth, modify the morphology of the hair follicle and the hair shafts in a manner which can reduce ingrown hair, and also improve compliance with a daily-shave regimen. These types of conservative approaches which can be used on a sustained basis to maintain therapeutic benefits without the risk of side effects represent an excellent option. The drawback of these approaches is the time it takes to notice benefits which could be as long as two to three months.
The results of clinical studies on the use of professional hair removal lasers to manage PFB is impressive in demonstrating rapid resolution of the condition. However, no data is available on the safety of repeated long-term use of these laser treatments necessary to sustain efficacy. Professional hair-removal laser treatments are expensive, and the convenience and safety of other options which can provide a similar degree of efficacy makes those appealing options as first course of treatments. Recent studies on the combination therapies of laser and Vaniqa in hair removal [26,27] suggest this combination strategy for use in PFB. A recent patent application by Shander et al. [28] using a validated laboratory model for hair-growth inhibition, which is highly predictive of clinical efficacy, demonstrated the use of topical treatments to enhance and promote the effectiveness of low flu – ence photo-thermal treatments for hair-growth inhibition which are minimally effective when used alone. Overall chemical thermal synergies may represent the most appealing future treatment options that can exploit the effects of light – mediated thermal damage to hair follicles along with specific actions of hair growth retardants, altering growth and differentiation of hair shafts. One can envision periodic boosters with lower fluence laser treatments along with continued treatment of hair retardants to safely and effectively prevent the ingrown hair responsible for PFB. Such treatments may not require complete elimination of hair growth, but rather sufficient modification of the processes of cell proliferation and differentiation to prevent formation of curly hair. This would also allow subjects to comfortably maintain a daily shaving regimen conducive to preventing ingrown hair.
A laser hair-removal device approved for consumer self use which is being introduced for sale in the United States in 2008 [29] is not approved for facial-hair removal, and its use in African American subjects is contraindicated. But it is possible that a device with reduced fluence appropriate for hair retardation and hair-shaft modification may be extremely useful as an adjuvant treatment in combination with topically active hair retardants. The 980 nm diode or related diode lasers with wavelength > 980 nm could be considered as part of the laser/chemistry combination treatment for self-administration. The results of safety and efficacy in reports using IPL in combination with RF to reduce the risks of exposing dark skin to high optical energy fluences of lasers are encouraging [30]. A consumer-use device incorporating the aforementioned electro-optical synergy technology (ELOS) is presently being developed by Syneron Inc. for a variety of dermatological conditions, and may be appropriate for safer treatment of darker skin types.
Although there have been recent claims that laser treatment can cure PFB, there is a lack of well-designed short – and long-term studies with prospectively defined treatment parameters documenting short-term and long-term effects, as well as addressing the critical issue of the adverse effects of repeated laser treatments on dark skin. In addition, none of the published work were designed to adequately control hair-removal regimens before, during, and after treatment, and factors such as frequency of shaving can have a large impact on the overall number of lesions during the course of treatment. Indeed, the benefits of laser treatment may be to enable daily shaving, which then adds a synergistic benefit to the outcome of the laser usage. There are also deficiencies in developing the appropriate inclusion and exclusion criteria related to the severity and previous history of PFB in subjects. The laser methods for PFB treatment require continued treatments to sustain benefits of lesion reduction, and the risks of permanent pigmentation or other skin disorders from multiple treatments may outweigh any benefits for PFB. The ideal strategy would be to employ a convenient inexpensive treatment regimen which do not impose any risks or the need of supervision by medical staff. Such an option may be provided by low fluence self-treatment devices which may effectively reduce the number of lesions, and enable daily shaving to maintain a well-groomed appearance. The success of such devices may be augmented by topical treatments and appropriate shaving regimens.