Abstract
The less favorable results produced by the Q-switched ruby laser (Q-Ruby) than by the Q-switched Nd: YAG laser (Q-YAG) against Ota's nevus which were indicated by the authors' recent report7) are as follows; 1) the energy of ruby laser beam is remarkably absorbed at the layer of epidermal basal melanosis and already massively consumed there before getting to dermis, 2) therefore it is quantitatively not powerful enough to destroy Ota's nevus lesion at dermis, that is, dermal melanocytes, 3) consequently Q-Ruby is actually less effective than Q-YAG to Ota's nevus, especially, the deep-seated one. In order to overcome this penetration disadvantage of Q-Ruby against Ota's nevus, the authors originated the combined treatment of Erbium: YAG (Er: YAG) and Q-Ruby (Er: YAG+Q-Ruby). They evaluate the efficacy of the Er: YAG+Q-Ruby against Ota's nevus in comparison with that of Q-Ruby alone.A total of 47 Ota's nevus lesions of 20 patients were treated. Er: YAG laser (Aesculap: MCL-29) having a wavelength of 2.94μm and a pulsewidth of 350μsec, and Q-Ruby laser (NIIC: 113-101, and Spectrum: RD-1200) having a wavelength of 694 nm and a pulsewidth of 20~25 nsec were used in the trials. Laser irradiation was conducted under local anesthesia. In Er: YAG+Q-Ruby, Q-Ruby (fluences: 7.0-8.0J/cm2) was applied just after irradiation of Er: YAG (fluence: 4.0 J/cm2). In Q-Ruby alone, the fluences used were also between 7.0 and 8.0 J/cm2Each treatment of Er: YAG+Q-Ruby and Q-Ruby alone was separately performed only one time at the same lesion of the same patient. The clinical effectiveness of the two methods at each treated site was judged over a period of three months after irradiation. Skin biopsies were also performed for both photo- and electron- microscopic observation of post- irradiation change.The total effective rates of Er: YAG+Q-Ruby and Q-Ruby alone on Ota's nevus were 66% and 43% respectively without any side-effects. In effective rates according to lesional sites, there was prominent difference between the two methods except cheek (Er: YAG+Q-Ruby: 50-75 Q-Ruby alone: 25~44%). In those according to histology3), there was also remarkable difference between them in the deep-seated group, that is, diffuse (Di), deep dominant (DD) and deep (De) types (Er: YAG+Q-Ruby : 50-72%, Q-Ruby alone: 0~39%), while there was no difference between them in the superficial-seated group, that is, superficial (S) and superficial dominant (SD) types (75-86% in each method). Furthermore, there was especially prominent difference between them in types DD and De lesions of eyelid (Er: YAG+Q-Ruby: 67%, Q-Ruby alone: 11%) and in type Di lesions except eyelid (Er: YAG+Q-Ruby: 71%, Q-Ruby alone: 29%).The aforementioned more favorable results produced by Er: YAG+Q-Ruby than by Q-Ruby alone are thought attributable to prolongation of light extinction length of the ruby laser beam in dermis by Er: YAG's photoablative removal of epidermal basal melanosis which could prevent the beam from penetrating the skin deeper.
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