Ruby lasers (694 nm), used for hair removal includes:
— Epilaser/E2ooo (Palomar, Lexington, MA)
— EpiPulse Ruby (Lumenis, Santa Clara, CA)
— RubyStar (Aesculap Meditec., Irvine, CA)
Epilaser/E2000 (Palomar). With this laser, light is delivered through a fiber, and two different spot sizes (10 mm and 20 mm) are available. A retroreflector is built into the hand piece, allowing photon recycling and therefore higher energy delivery (Anderson et al. 1999; Ross et al. 1996). Depending on skin type or hair thick ness, a single pulse of 3 ms or twin pulses (i. e., two 3-ms pulses delivered with a delay of 100 ms) can be chosen. The E2000 uses a sapphire-cooled handpiece (Epiwand) to protect the epidermis during laser irradiation. The sapphire lens is actively cooled to o° or -1o°C and put in direct contact with the skin.
The long-pulsed EpiPulse Ruby laser (Lumenis) employs triple-pulse technology with 1o-ms intervals between pulses. This train of pulses keeps the follicle temperature sufficiently high to cause destruction. Epidermal cooling is achieved by applying a thick layer of cooled transparent gel on the skin.
The RubyStar (Aesculap-Meditec) is a dualmode ruby laser that uses a contact skin cooling method. It can operate in the nanosecond Q-switched mode for the treatment of tattoos and pigmented lesions and in the normal millisecond mode for hair removal. Its integrated cooling device consists of a cooled contact hand-piece which precools the skin before laser pulse delivery.
Although the mechanism of ruby laser induction of follicular injury is likely to be thermal, the precise contributions of photomechanical damage or thermal denaturation to follicu-lar injury are unknown. It is possible that after absorption of radiant energy, the large temperature differences between the absorbing mela-nosomes and their surroundings produce a localized rapid volume expansion. This would then lead to microvaporization or "shock waves," which cause structural damage to the hairs (Anderson et al. 1983). On the other hand, thermal denaturation leading to melanosomal damage is also possible. Histologic evaluation of laser-treated mouse skin has revealed evidence of thermal coagulation and asymmetric focal rupture of the follicular epithelium (Lin et al. 1998). Secondary damage to adjacent organelles could theoretically result either from thermal diffusion or from propagation of shock waves.
Because of its comparatively short ruby laser wavelength, this hair removal system is best suited for the treatment of dark hair in light skin. It also may be more efficacious than longer wavelength devices for the treatment of light hair or red to red-brown hair (Ross et al.
1999). Because of the high melanin absorption coefficient at 694 nm, the ruby laser must be used with caution in darkly pigmented or tan patients.
A number of reports have documented the efficacy of ruby laser hair removal in varying types of skin using different laser parameters. The published hair reduction rates have ranged from a 37% to 72% reduction 3 months after one to three treatments to a 38%-49% hair reduction 1 year after three treatment sessions (Williams et al. 1998). As would be expected, multiple treatments at 3- to 5-week intervals produce a greater degree of hair reduction than is seen after a single session. In general, higher delivered fluences do lead to better hair removal success, although complications also increase.
Studies with larger numbers of patients have confirmed that hair counts are reduced by approximately 30% after a single treatment with ruby laser (Williams et al. 1998). The effects of multiple treatments sessions are additive, as hair counts are reduced by approximately 60% after three or four treatment sessions. Whether 100% permanent hair removal can be achieved remains open to debate.
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