摘要： The treatment of superficial vascular lesions on skin are among the most common sought-after dermatological laser procedures. The treatment method is based on the absorption of laser light by haemoglobin in blood, which results in the transfer of heat and wanted vessel wall damage. The yellow wavelength range is considered ideal for this purpose, because of the high absorption peak of haemoglobin around 577 nm. However, the yellow spectral range is challenging for any laser technology to produce, which is why there are only a few options on the market, notably the pulsed dye laser (PDL), resulting in limited and expensive treatments. We report on a clinical study that assessed the efficacy of a compact high-power yellow laser system designed for the treatment of cutaneous vascular lesions, such as telangiectasia. The laser system is based on frequency-doubled vertical-external-cavity surface-emitting lasers (VECSELs); a novel technology, which has emerged as an attractive alternative to solid-state, and dye lasers due to the enhanced functionality and broad wavelength coverage [1,2]. The system includes a handheld scanner for an easy and fast delivery of laser light onto skin and is capable of emitting 8 W (continuous wave) at the challenging 590 nm wavelength range (see Fig. 1 Left). The first head-to-head clinical study (ClinicalTrials.gov Identifier: NCT03472859) compared the efficacy of the VECSEL-based yellow laser system and a traditional green KTP laser in the treatment of facial telangiectasia [3]. Altogether 24 subjects participated and completed the clinical study. The subjects were randomized to receive KTP treatment on one side of the face and yellow laser treatment on the other side. Each subject received 1–2 treatments with both lasers. The efficacy of the treatments was assessed by blinded investigators using before and after images taken with a Visia imaging system (see Fig. 1 Right). There was no statistically significant difference between the efficacies of the two lasers; 83% of the subjects had at least 50% improvement after the first treatment with the yellow laser system and similar results were observed for the KTP laser. Treatments with the yellow laser system were 4.7-fold faster than with the KTP but subjects experienced more pain, which limited the use of higher fluences. The yellow laser system settings were 5.6-8.1 J/cm2, whereas as green KTP settings were 20–30 J/cm2. In the next study, we will add a cooling device to the yellow laser to enable the use higher fluences, which is expected to lead to better results, as demonstrated by Kapiciogly et al [4].