We have been using low power laser therapy (LT) in 152 patients with chronic pain of different origins at our pain clinic in the past four years. The effect of LT was evaluated in two fashions: the immediate effect and the long term effect. The averaged effective ratio was 66.4% for the immediate effect. In the immediate effect, Very good were 36 cases (23.7%), good 65 cases (42.8%), no change 50 cases (32.9%) and worse a case (0.6%). The averaged effective ratio was 74.3% for the long term effect. In the long term effect, no pain were 21 cases (13.8%), light pain 92 cases (60.5%), no change 39 cases (25.7%) and worse was not observed. LT was particular effective in patients of postherpetic neuralgia (PHN). The total effective ratio were high about 90% for PHN. Complications attributable to LT included general fatigue, hot sensation of the irradiation areas and and temporally increased pain. However, no serious side-effects were obtained in this series of patients. In future, LT might become popular due to its simplicity and noninvasiveness.

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The author has had the opportunity to make a brief review of the present status of use of medical lasers in plastic surgery, covering fields of application from head to toe. As plastic surgery covers so wide an anatomical range and the variety of lesions is so great, different machines are needed to meet the various clinical requirements.
The author has had the honour of selecting contributors who are recognized as leaders in their special fields of laser surgery and to provide them with the opportunity to present their views in their areas of expertise.

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The CO₂ laser (noncontact-type scalpel) and Nd-YAG laser (contact-type scalpel) are used in plastic surgery. The history, principle of oscillation, system, indications for lasers, mainly the most popular CO₂ laser, are described. A summary of the contact-type Nd: YAG laser, which was developed recently, and Nd: YAG/CO₂ complex lasers are described briefly. The laser oscillation tube, guidance tract, and handpiece have been modified markedly. They are being miniaturized with improved mobility. Ease of operation improved markedly. However, we should abandon the excessive expectation of the laser being a“magic ray”, as was put forth immediately after its advent. We should understand well the physical properties and actions on the living body of the laser and carefully evaluate its advantages and disadvantages before clinical applications.

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Since 1977 CO₂ Laser had been used mainly in plastic surgery, aesthetic surgery and dermatology in Japan. Initially, it was used for laser scalpel (non-contact scalpel) instead of scalpel (cold knife), but recently the ability of vaporization is valued. We treated small some benign skin tumors such as nevus cell nevus, verruca vulgaris, angioma, seborrheic keratosis, etc. using vaporization. We achieved good results compared to the conventional therapy such as surgical excision, cryosurgery, skin abrasion etc. These results depended on not only surgeon's techniques but on histological features of each tumor. So we thought indication of CO₂ laser vaporization was determined by histological findings. Tumors seated not only epidermis and/or super facial dermis but from the mid to the lower dermis had possibility of recurrence after incomplete irradiation and of scar formation after too much irradiation, so we had not better to apply such conditions. In verruca vulgaris, some of them were not effective by only vaporization, so we combined vaporization and laser scalpel for such cases. In order to get better results, it is necessary to appreciate histological characteristics of each skin tumors.

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Recently, it has become clear that limitations of argon laser therapy in the treatment of benign cutaneous lesions, because some grades of scarring complication were always occured after the argon laser therapy. The latest application and limitations of argon laser treatment were discussed.
1. Generally the argon laser must not apply to the lightening of abnormal coloring of port wine stains because of surface scarring. Especially in the cases of children and females under the age of thirty-years old, prominent scarring is always occured.
2. The argon laser may only apply to the cases with cavernous elevated changes of port wine hemangioma over the age of thirty-years old.
3. The argon laser may also apply to the small benign cutaneous lesions under the size of 3cm-diameters, because scarring is not so prominent in these small lesions. It is applicable to the cases with teleangiectasias, elevated or flat small pigmented lesions such as nevocellular nevi, nevi spilus and senile pigmented macules.

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With the advent of the surgical rod for Nd-YAG Laser, the laser now provides three independent functions, namely cutting, coagulation and vaporization, that may be utilized in the field of surgery.
The use of Nd-YAG Laser is broadly classified into two areas: contacting and noncontacting. We have been performing fundamental studies on these functions for clinical applications using animal organs such as rat and porcine liver. As the types of clinical applications based on the results of animal studies have broadened and the number of patients enrolled in our studies have increased, we summarize the fundamental and clinical aspects of Nd-YAG Laser procedures in this paper.

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Selective photothermolysis of port-wine stains induced by Candela model SPTL-1P (577nm) and SPTL-1 (585nm) flashlamp pumped pulsed dye lasers were examined light and electron microscopically. Immediately after irradiation, red blood cells agglutination and heat necrosis were found at the dilated vessels in the dermis, and perivascular collagen fibrils necrosis was minimum. Twenty-four hours after irradiation, a lot of inflammatory cells were infiltrated around the necrotic vessels. One month after irradiation, the area in which dilated vessels had showed necrosis was replaced by granulation tissue. No recurrence or scar formation was observed in the dermis 6 months after irradiation. Comparing to SPTL-1P (577nm), SPTL-1 (585nm) showed deeper penetration in the dermis while the selectivity of vessel necrosis was not different between them. In the cases with epidermal hyperpigmentation, epidermal necrosis and reepithelization was found after irradiation. The reepithelized epidermis showed the state of pigment blockade for several weeks, and returned to normal pigmentation within 6 months.

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Histological and clinical findings of portwine stains treated by pulsed dye laser were studied in comparison with argon laser treatment. Histologically pericapillary scarring in the dermis were remarkably slight with the dye laser treatment in comparison with the argon laser, although the dye laser treatment were almost similar to the argon laser in clearing effects of dilated capillaries in the dermis. The superior clinical results of the dye laser were mainly due to no scarring effect in the dermis. The difference of histological and clinical responses between dye laser and argon laser can be explained by the theory of thermal relaxation time.

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295 patients (305 lesions) with port-wine stains (PWS) were treated using the flashlamp dye laser (Candela SPTL-1P, SPTL-1). The patients whose lesions did not lighten significantly at the first treatment would receive two or more treatments at intervals of more than one month. The results of the 305 total lesions were excellent in 85 lesions (28%), good in 186 (61%), fair in 23 (7%), poor in 11 (4%). Thirty-four lesions which were judged to have less satisfactory results, received only one or two treatments.All the lesions which received three or more treatments were judged to have satisfactory results. Slight scar formation were found in 5 lesions, They were caused by scratching and not caused by laser irradiation itself. Twenty-two lesions developed transient hyper or hypopigmentation, which returned to normal skin color within six months. From clinical findings, it appeared that the flashlamp dye laser is highly effective and safe in the treatment of PWS and repeated additional irradiation to the same site at regular intervals could attain high efficacy at any site of the patients of any age. When we treated the patients with very dark skin, skin abrasion was performed first and then irradiation was done during the stage of hypopigmentation following the epithelization, so that desirable consequence was obtained as the result of the increased transmittance of the laser beam.

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We have developed new Ruby laser system (TMRL series) for the treatment of hyperpigmented skin lesions, such as pigmented nevus (melanin particle deposition), tattoos and so on. The prototype of this series invented in 1980 included a lens-type applicator, which was attached to the oscillator. In 1981 we developed a kaleidoscope (quartz square pillar), which enables us to obtain a homogenous output energy distribution. In addition, it provides a square area of irradiation. So, we can perform efficient treatment. In 1982 we also succeeded in developing a fiber optic induced system using quartz fibers, first in the world. The fiber manipulator and the handpiece separated from the oscillator assure us of much better handiness. After that we have improved the power supply into a smaller and lighter one and adopted a shorter irradiation interval. In 1987 we commenced delivery of commercial units, model LRT-301A, after obtaining the approval for its manufacture and clinical application from the Ministry of Health and Welfare of Japan. This equipment is characterized by the output energy of 20-40J/cm², pulse width of 2 msec, irradiation interval of 10 sec, irradiated area of 10×10 and 15×15mm, and electrical input of 100V (single phase), 30A, 50/60Hz. We can obtain far better results by ruby laser treatment than by the conventional methods, though we realized its limitation. We are now developing a shorter pulse width in expectation of better selective effects of laser treatment.

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The ruby laser irradiation causes selectively damages of the cutaneous melanin granules, but the cutaneous histological changes after the irradiation has not been well described. We applied the ruby laser to an excised skin using TOSHIBA Model LRT-301A. in this study, histological examinations were carried out light and electron microscopically. The results revealed as follows; exposure of 9J/cm²: Vacuolated changes were seen on the cells with melanin pigment in the basal layer. 16J/cm²: The vacuolation of cells among the basal cells were observed as elongated and degenerated in shape, The ring-like degeneration showing a crater was seen at the site of incontinentia pigmenti histologica in dermal papilla. 25J/cm²⁾: Diffuse degenerations were seen in the basal layer. Excoriation were most frequently seen at this energy radiated akin. 40J/cm²: Diffuse degenerations were also observed in epidermis and dermal papilla with subepidermal cleft. In patients with seborrheic keratosis, senile pigmentation, nevus pigmentosus and nevus Ohta treated using ruby laser, the almost similarly histological alterations were observed. The study demonstrated that in the therapeutic efficacy of ruby laser on the dermal pigment disorders, the high energy irradiation was not always necessary, because over dose of energy-irradiation was absorbed by epidermal melanin granules (epidermal trap) and the basement membrane was also damaged.

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285 various pigmented skin lesions from 282 patients, using the square and uniform intensity ruby laser equipment for the past two years and ten months, have been treated. Laser effects on 44 skin specimens, which were excised through conventional operations, have also been studied histologically. The effect of laser therapy was graded as excellent (around 90% improvement), good (around 70% improvement), fair (around 50% improvement) and poor (under 30% improvement).
The effective rate of 6-month or more follow-up cases was 12/96 (12.5%) in pigmented nevus, 13/75 (17.3%) in nevus spilus, 3/5 (60.0%) in Becker's nevus, 3/7 (42.9%) in epidermal nevus, 9/17 (52.9%) in senile freckle and 9/12 (75.0%) in seborrheic keratosis, respectively.
As for a pigmented nevus, effective results may be rather expected when no or very few junctional nevus cell nests are in the lower epidermis, and when nevus cells are sparse and relatively limited in the upper dermis. As for a nevus spilus, tardy type seems to respond to the ruby laser treatment more satisfactorily than congenital type. Anyway, preliminary test irradiation is recommended and evaluated before further treatment of the whole lesion in both extensive pigmented nevus and nevus spilus.
Moderate to high effective rate may also be expected for epidermal nevus, senile freckle and seborrheic keratosis because of reliable epithelial peeling effect of ruby laser beam. Some discussion was also performed how to improve the effectiveness of ruby laser treatment.

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It is of vital importance for laser therapy in hyperpigmented skin lesions to find optimum conditions with respect to wavelength, energy density, pulse width, treatment interval, treatment method (for example, the 1st irradiation immediately followed by the second), etc. In this study we irradiated dye laser (585nm), ruby laser (694.3nm), alexandrite laser (750nm) and Nd-glass laser (1060nm) to the skin of spotted black guinea pigs and hyperpigmented human skin lesions to study whether differences in the wavelength of pulse laser may affect therapeutic results or not. Consequently, it was found that rudy laser and alexandrite laser were effective against skin lesions due to melanin particle deposition and Nd-glass laser against tattoos. The pulse width dependence was discussed between 0.15-2msec. using rudy laser. Melanin particles deposited in the basal layer were more selectively destructed by the shorter pulse laser.
When the energy density was increased above a certain threshold value, non-selective damage of tissues occurred. Since selectivity is one of the important features of laser therapy, an inadequately high energy irradiation is considered useless. In the meantime, we investigated retrospectively 645 patients who underwent ruby laser treatment at our hospital and could be followed up for more than 6 months during the last decade. The treatment was effective for 45% of patients with congenital nevus spilus. The effective rates were 94%, 50%, 80%, 59%, 69%, 22% and 38% in the groups with acquired nevus spilus (Becker), nevus cell nevus, epidermal nevus, nevus pigmentosus senilis, seborrheic keratosis, cafe-au-lait spots and Ota's, respectively. Nevus cell nevus involving the surroundings of the eyelid, palm, sole and lip could be more effectively treated, with a high effective rate of 84%. In the treatment of superficial hyperpigmented skin lesions, rudy laser with 450μsec. and 15J/cm² was less effective than the conventional ruby laser with a longer pulse width. To sum up, short pulse laser in the visible region, is thought to be suitable for the treatment of superficial hyperpigmented skin lesions, short pulse rudy laser or alexandrite laser for deep melanin particle deposition, and short pulse Nd-glass laser for tattoos in Japanese patients, respectively.

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