INTRODUCTION
The use of light sources offers an effective and safe alternative to traditional hair removal methods. Traditional methods are often tedious and painful. Hair removal treatment with photo-epilation is a quick, non-invasive procedure in which intense light is used to damage hair shafts and hair follicles. Photo-epilation is particularly successful with the EpiLight Hair Removal System due to its flexible design. The EpiLight Hair Removal System uses intense polychromatic light with a broad wavelength spectrum from 590 nm to 1200 nm and various cut-off filters (590, 615, 645, and 695 nm) to remove unwanted hair from all areas of the body. In addition, the system provides a large spot size to cover large body areas quickly, an energy fluence range from 30 to 65 J/cmq and multiple pulse sequencing with a controlled delivery time to accommodate varying amounts of melanin in the epidermis and hair, thereby minimizing tissue damage. The system operates on the principle of selective photothermolysis in which light is specifically absorbed by the target tissue in a sufficient amount to cause its destruction without harming surrounding tissue. In the case of hair removal, the target chromophore is melanin, which is found in melanocytes in the hair shaft, hair follicle and papillae.
Melanin is present in the epidermis, as well, which must be taken into consideration when treating Fitzpatrick skin types IV and V. In dark skin types, the concentration of melanin in the epidermis is similar to the concentration of melanin in the hair follicle and thus, appropriate parameters must be chosen to avoid damaging the skin. Nevertheless, safe epilation of darkskinned individuals can be achieved by using higher cut-off filters and modulating the pulse intervals. Higher cut-off filters omit light at lower wavelengths, where the greatest absorption of light by the epidermis occurs. Therefore, the longer wavelengths can facilitate safe treatment of the skin, while still possessing the ability to penetrate and affect the deeper parts of the hair follicle. Furthermore, increasing the delay time between pulses allows the epidermis to cool and prevents harm to the skin, since the thermal relaxation time of the epidermis as a unit is approximately 3-10 ms and the thermal relaxation time of the hair follicle as a unit is in the range of 40 to 100 ms. In this study, 26 patients with skin type IV or V underwent EpiLight treatment. One hundred treatments, consisting of a single pass and various fluences, were conducted over 15 months.

METHOD
Twenty-six patients with skin type IV (n=ll) or V (n=15) were treated in various body locations (i.e. face, arms, legs, bikini line) to remove unwanted hair. Skin type IV patients were classified as those of Oriental or dark Mediterranean descent, while skin type V patients were of East Indian descent. Patients were pretreated with 4% hydroquinone for one month before undergoing photo-epilation. The rationale behind this drug treatment was to deplete some of the epidermal melanocytes of melanin in order to decrease the risk of postinflammatory hyperpigmentation. A test spot about the size of a dime was conducted on the nape of the neck and was examined after one month to determine if postinflammatory hyperpigmentation had developed. When a sensitive area such as the upper lip or cheeks was to be treated, then a second test spot was performed beneath the chin.
Treatment for patients with skin type IV included a 645 nm cut-off filter, average energy fluence of 37 J/cmq and triple pulses with a general duration of 2.8 ms and a delay of 57 ms between pulses. Skin type V individuals were treated with a 695 nm cut-off filter, energy fluence of 37 J/cmq and 4 pulses of 2.9 ms duration with a 97 ms delay between pulses.

RESULTS
The treatment parameters that were chosen, aside from the 97 ms delay time between pulses for skin type V patients, achieved good results. The delay time allowed the target tissue to cool too much and thus, decreased the efficacy of the treatment. Therefore, the delay time was reduced to 60 ms for subsequent skin type V patients. Examination of the test spot on the nape of the neck showed a 9% occurrence of transient epidermal erosion. Epidermal erosions occurred in 3% of the patient population with full treatments. No blistering occurred in any of the patients and no evidence of permanent hyper-or-hypopigmentation or scarring was observed. Hair counts after treatment revealed that one treatment to skin type IV individuals produced a 42% reduction in the number of hairs, while three treatments increased the reduction to 52%. The results for skin type V individuals were not as dramatic as for type IV with three treatments producing a 37% reduction in the number of hairs.

SUMMARY
The EpiLight Hair Removal System provides safe treatment of darker skin types due to its adjustable wavelength spectrum and flexible design. Moreover, the ability to treat a wide variety of hair colors is unique to the system. Gold reported in a long-term epilation study that although the effectiveness of treatment varies for different hair colors, all hair colors were indeed affected by the treatment. In addition, Werner et al reported on treating 200 women and 80 men with various skin types and hair colors. In view of the results achieved, EpiLight should be considered as a preferred alternative to traditional treatment methods.

Fig.1: 26 year-old female (skin type V) with hair under the chin. Patient also has scarring from previous electrolysis treatment
Fig. 2: clearance after 3 treatments. Note that the scarring has lightened.

Fig. 3: 25 years old male (skin type V)
1 month after test treatment
to area underneath the chin.

Fig. 4: 36 years old female (skin type V) with hair on the forearm.
Fig. 5: clearance after 1 treatment.

Fig. 6: 21 years old female (skin type V) with hair and ingrown in the bikini line.
Fig. 7: clearance after 1 treatment. Note that in-grown hairs have cleared considerably.