With the advent of combined optical and RF technology, various clinical trials have been conducted to elucidate the potential of the system’s application on different hair types and skin colors by varying the treatment settings, as well as the number of treatments administered (Table 7.4). Del Giglio and Shaoul [24] conducted a recent multicenter study using 60 subjects with Fitzpatrick skin types ranging from II-V and varying hair colors for treatment. In the study, optical energy ranged from 15 to 28 J/cm2, and RF energy ranged from 10 to 20 J/cm3. All subjects received three treatments, six to eight weeks apart. Hair counts were performed prior to treatment, and three months after the last treatment. Maximum hair reduction was observed at two to eight weeks. At three months, hair clearance ranged from 64 to 84%, depending on the anatomic site. In addition, 12 subjects with white, blond hair displayed an average clearance of 52% at six months. Treatment was most effective in the axillary region. In most patients, high RF energy (15-20 J/cm3) was used, and the results indicate that efficacy is determined by the level of RF energy, and not optical energy.
A study which consisted of 40 adult subjects with Fitzpatrick skin types II-V and various hair colors conducted by Sadick and Shaoul [38] showed maximum hair reduction occurring from six to eight weeks following treatments, and progressive decrease of hair density was observed following each subsequent treatment. Subjects received four treatments at 8- and 12-week intervals, over a period of 9-12 months. Depending on the skin and hair phenotypes, light energy ranged from 15 to 30 J/cm2. Higher optical energy was used in lighter skin phenotypes and hair color. The RF current ranged from 10 to 20 J/cm3, depending on the anatomic site, with higher RF energy used in facial areas as compared to the lower body regions. The results were monitored until six months after the last treatment, at which time the average clearance of 75% was observed at all body locations, with the best results (85% clearance) seen in the axillae and legs. As expected, darker phenotypes provided greater hair-removal efficiency.
Sadick and Laughlin [45] examined the long-term photoepilatory effect on blond and white hair using 36 women with skin phenotypes ranging from I-V. The chin and upper lip were treated with four sessions over a 9- to 12-month period. The level of RF energy was 20 J/cm3 , while optical fluences varied from 24 to 30 J/cm2. Maximum reduction in hair counts was observed at six to eight weeks after each treatment, with an average clearance of blond and white hair of 48% at six months follow-up after the last treatment (Fig. 7.3a and b). Side effects were minimal, with 8% of patients reporting transient hyperpigmentation that did not require therapy, and 14% having mild erythema which resolved in 24 hours. While the slightly higher photoepilatory efficiency for blond hair (52% clearance) versus that of white hair (44% clearance) shows the promise of this combined modality system as a favorable alternative to treat this previously difficult-to-treat patient management subgroup, it should be noted that pure laser sources utilized for the removal of darker hair phenotypes are still more advantageous clinically.
Laughlin [46] conducted a study using ten patients, seven of who were East Indian patients with Fitzpatrick skin type V and three African-American patients with Fitzpatrick skin type VI. The RF energy was set at 18 and 20 J/cm3 for skin types V and VI, respectively. Optical energy was set from 16 to 20 J/cm2 for skin type V and from 14 to 17 J/cm2 for skin type VI, respectively. Serial photography and clinical examination were used to
evaluate the subjects at one to three days, two weeks, one month, and four to seven months after the final treatment to determine hair loss and adverse effects, notably dyschromia and scarring. Two blinded observers working independently carried out hair counts. The results showed that 50% of subjects obtained a hair loss of more than 35%. The mean hair loss for the entire group was 30.20%, with a range of 13-75.4%. None of the study participants developed any blistering within the first 72 hours of treatment, and the absence of early epidermal injury differentiates this method of treatment from those methods using pure optical energy, where blistering can occur [17,47]. Lasers and IPLs are associated with infrequent complications; the greatest risk being associated with the treatment of darker skin types [32,48]. The adverse events including hyperpigmentation, hypopigmentation, blistering, and crusting, are often associated with the treatment of skin types IV and above [49]. However, epilation with combined RF and optical energy in this study of patients with the darkest of skin types was associated with a zero rate of dyschromia, which suggests that this method of treatment could eliminate the expected risks of photoepilation in skin type V and VI by providing for a better therapeutic margin of safety for the treatment of pigmented skin.
Goldberg et al. [50] studied 15 subjects with nonpigmented facial hair and Fitzpatrick skin types II-IV. Ten of the subjects were clinically determined to have white terminal hair, and the remaining five were noted to have fine, nonpigmented vellus hair. The level of RF energy was set at a constant 20 J/cm3 for all study subjects, while the chosen optical flu – ences varied between 24 and 30 J/cm2 and were delivered in a short pulse profile. Hair counts were taken from standardized digital photos obtained before and six months after final treatments, where baseline hair count was determined by two nontreating physicians.
Half of the face was pretreated with a 20% solution of aminolevulinic acid, a light absorbing photosensitizer shown to promote photoepilation, one hour prior to treatment with the optical bipolar RF device [51]. Topical photosensitizers including 5-amino levulinic acid (ALA) have been previously studied for hair removal [12]. ALA is the first product in the hemesynthesis cascade, which, when present in excess, is converted to protoporphyrin II, a potent photosensitizer. Twenty percent of ALA is absorbed by hair follicles and subsequently converted to protoporphyrin IX in a period of several hours. Subsequent exposure of skin to light energy activates protoporphyrin IX, leading to the formation of singlet oxygen, which damages follicular cell membranes [12,52]. In this study, hair loss of 35% was reported at six months after the first and only treatment. When pretreatment with topical ALA was provided, the average hair removal of terminal white hair was found to be 48%. Nonpigmented hair can be successfully removed with a combined optical bipolar RF source, and these results are further improved with the preapplication of a topical photoabsorbing agent. White hair was also found to contain melanin within the follicular structure, albeit not in the actual follicle itself. This melanin is sufficient for absorbing the optical energy delivered by the combined optical RF device.
A multicenter study involving 69 patients with skin types I-VI were evaluated at 1, 7, 30, and 90 days after a one-treatment session [53]. The optical energy component was delivered with a pulse duration of 25 ms and energy fluence ranging from 14 to 20 J/cm2, while the RF energy was delivered with a pulse duration of 200 ms with energy density ranging from 10 to 20 J/cm3. At 90 days after a single treatment, the mean hair count was reduced from baseline by an average of 47%, with best results achieved when treating the arm (65%), followed by the axilla (49%) and legs (44%). The percentage of hair reduction was statistically significant for all three hair colors, with a mean hair count reduction of 43% for black hair, 49% for brown hair, and 35% for blond hair. The use of longer pulse durations permits thorough thermal injury to the entire follicular unit, resulting in more permanent hair removal while producing less thermal damage, as is seen in this study [34,54,55].
Shroeter et al. [56] recruited 17 patients with blond hair; seven of who had skin type I and 10 patients with skin type II. The mean optical energy used per patient was 23.3 J/cm2 and the mean RF was 18.6 J/cm3. A mean hair reduction of 57.4% was obtained after an average of 8.5 treatments. A clear trend between hair removal and number of treatments was established in this study, with better results depending on the increasing number of treatments.
Schulze et al. [57] treated facial hair in 17 subjects with Fitzpatrick skin types I-IV. The optical fluences ranged between 35 and 50 J/cm2 , and pulse duration of 100 ms. Radiofrequency energy densities ranged from 10 to 50 J/cm3. Treatment areas received between one and four treatments over a six-month span, with four to six week intervals between treatments. There was a reported mean hair reduction of 50% after an average of 1.9 treatments at a mean follow-up period of 2.6 months. There was a trend toward greater hair reduction with thicker and darker hair, although in two cases there was a marked reduction in thinner hair. Pain was proportional to hair pigmentation, density, and thickness, and occasionally was severe.
A multicenter study conducted by Sadick, Mullholland, and Shaoul [42] recruited 45 patients with Fitzpatrick skin types II-VI and with various hair colors. Treating a variety of body sites such as the legs, bikini line, axilla, and back, the laser energy density range used varied from 30 to 42 J/cm2, while the RF energy range was 30-40 J/cm3. Maximum reduction in hair was observed from two weeks to two months after a single treatment (Fig. 7.4a and b). Maximum average clearance was seen in the bikini line (78%) followed
closely by the legs (75%), axilla (72%), and back (65%). The treatments were well-tolerated by the subjects when concomitantly employing a forced air-cooling device over the use of topical anesthesia. Figure 7.4 (a) Before combined 800 nm diode/radiofrequency (RF) hair removal; (b) after combined 800 nm diode/RF hair removal (three treatments; month 9 (6 months after last treatment)); optical energy = 36 J/cm2, RF energy = 36 J/
cm3.