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Background: Fractional ablative and non-ablative lasers are useful treatments for skin rejuvenation. A procedure that provides the sequential application of fractional ablative followed by non-ablative laser treatment may reduce patients’ downtime and deliver better cosmetic results than with either laser alone. Objective: The purpose of the current study was to demonstrate the ameliorative and therapeutic effects in skin remodeling of the synergistic use of the two laser wavelengths (fractional ablative CO2 and non-ablative 1540 nm) with three different types of pulse shapes, S-Pulse (SP), D-Pulse (DP) and H-Pulse (HP), through which the CO2 laser can emit, performing an ex vivo histological evaluation. Methods: In this prospective study, ex vivo sheep inner thigh skin was chosen due to its similarity to human skin tissue, and a histological evaluation was performed. Three irradiation conditions, using all of the three CO2 pulse shapes (alone or averaged), were investigated: (1) 10.600 nm alone, the sequential irradiation of the two wavelengths in the same perfectly controlled energy pulses (DOT) for the entire scan area; ((2) 10.600 nm followed immediately by 1540 nm; and (3) 1540 nm followed immediately by 10.600 nm). Results: When comparing ablative to sequential irradiations, the synergy of the two wavelengths did not alter the typical ablative pulse shape of the 10.600 nm laser alone. With the same CO2 pulse shape, the lesion depth did not vary with the synergy of the two wavelengths, while thermal lesion width increased compared to CO2 alone. The ablation rate was achieved, while the total thermal lesion coverage in the scanning area of CO2 − 1540 lasers was greater than when using CO2 alone and then the other sequential irradiation. Conclusions: This study provides important preclinical data for new and early uses of the novel 10.600/1540 nm dual-wavelength non-ablative fractional laser. The synergy of the two wavelengths enhanced all the benefits already available when using CO2 laser systems both in terms of tone strengthening, thanks to a greater shrinking effect, and in terms of stimulation and collagen remodeling thanks to a greater volumetric thermal effect.

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The effects of 1064 nm laser on red telangiectasias using pulse shape modulation Dear Editor, Facial and leg telangiectasias are common cosmetic concerns for both men and women of all skin types and ages. To date, various treatments for these issues, particularly leg telangiectasias, have frequently failed or resulted in negative side effects. 1 Among these, lasers, electrosurgery, sclerotherapy or surgical removal were used. Each technique has its own set of benefits and drawbacks. Sclerotherapy, for example, is effective for large vessels but not a good option for small vessels. It is performed by injecting a sclerosing agent into the vessel and this may cause endothelial damage, thrombosis, vessel wall necrosis and subsequent fibrosis. 2 Surgical removal of facial telangiectasias has been suggested, but this technique requires a 2 mm incision under local anaesthesia. It is considered technically difficult to perform with high variability in results depending on the surgeon's expertise. For example, laser treatments that use Neodymium-doped yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate laser, pulse dye, diode or intensive pulsed light technology penetrate the skin at different wavelengths (depending on the technology) to break the oxyhaemoglobin (Hb-O2) and damage the vessel wall. 3 Nd:YAG laser at 1064 nm has good tissue penetration and can treat vessels up to 3-4 mm in diameter.It is suitable for skin types I-VI with or without tan 4,5 and for the treatment of vessels of the lower limbs. 6 Long-pulsed Nd:YAG laser has been used in treating larger and deep-seated leg/facial veins. [7][8][9] To achieve the best therapeutic outcome during laser-induced photothermolysis of vascular skin lesions, dynamic changes are crucial. The temperature threshold for rapid photoinduced thermal damage is around 70 • C. Therefore, identifying markers to show when this temperature threshold has been reached is important. The presence of Met-haemoglobin (Met-Hb), which is produced when haemoglobin (Hb) undergoes photoinduced oxidation, indicates that the temperature has risen to this threshold. 10 Met-Hb formation has already been shown to increase the effectiveness and safety of laser treatment.Numerous studies have shown that heat causes Hb modification in the blood vessels. 11,12 This change is the outcome of oxidative processes converting Hb and Hb-O2 that result in Met-Hb formation. This is a distorted haeme protein, and its denaturation is one of the first events that can be seen when blood is heated. 13 Met-Hb precipitates via haemachromeThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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