Ota nevus, also known as supraocular frontal brown nevus, ocular dermal melanocytosis, ocular dermal melanosis, and melanocytosis of the eye mucosa and skin, was first reported by Masao Ota in Japan in 1938, and is therefore often called Ota nevus, which is a dark brown patchy lesion affecting the sclera and facial skin innervated by the trigeminal nerve. It is present at birth in 65% of patients, and the rest appear between the ages of 10 and 20. The lesions are pale cyan, brownish-black, black or tawny patches with a dark central color that fades to a lighter edge. The color of the lesions is aggravated by sunlight, exertion, menstruation, etc. Some of them become deeper and enlarge during puberty. The most common sites for this disease are around the eyes, temporal area, forehead, zygomatic area and nasal flank, i.e. the area where the first and second branches of trigeminal nerve are distributed, mostly unilaterally, and occasionally bilaterally. The treatment of nevus of Ota today, no matter where you go, domestic or foreign, is to use laser treatment, and there is no other more amazing technology. You may say that you have seen on the advertisement what pigment extraction, targeted removal, or what super Gaussian technology, etc., which you do not know and feel very magical, but it is certain that these are actually some treatment principles of laser. Don’t change the vest and you won’t recognize it. And since it is called advertising, today it is this pigment extraction, maybe tomorrow it will be changed again, and you will think there is a new technology again if you are not careful. In China, there is a saying that people have a lot of courage, the land has a lot of production, to be honest, in China to really make a lot of money, but really are those who do so. In fact, leaving aside the seemingly profound medical knowledge, think about it and you will know that any piece of equipment or new technology is not likely to be produced or developed by a hospital, the hospital does not have a plant, no production line, no workers, no ability to produce their own equipment, nor is it a research institution, no research team to develop new technologies, laboratory conditions, and the powerful funds required, hospital doctors are at work every day to see patients, and do not have those who are doing so. In the work to see patients, there is no more free time to do scientific research for decades, even if writing articles is purely boring promotion mandatory requirements, forcing everyone to copy the East, copy the West, so you can be sure, sure, extremely sure, any hospital equipment or new technology, can only go to the manufacturers to buy. And what are manufacturers producing equipment for? It is to sell the equipment to earn money. Since this is the case, think about it you will know that manufacturers are seeking to maximize sales profits, manufacturers produce equipment whether good or bad, even if the equipment is bad, but also hope that the whole world’s hospitals to buy their equipment, how can there be a certain equipment or new technology (especially the claim that much better), hidden, only sold to a hospital, other hospitals do not have, or even never heard of, and only a hospital What about exclusive purchase? Then the manufacturer of the equipment sold this one, not to lose money. Think about Bentley and Rolls Royce, these super luxury cars are priced several times higher than lasers, and they have to sell several thousand units a year, otherwise who will feed who? There are three types of lasers commonly used for nevus of Ota treatment: Q-switched ruby laser, Q-switched emerald laser, and Q-switched Nd:YAG (garnet) laser. The difference lies mainly in the different gemstones used in the core part of the laser, which are ruby, emerald and garnet respectively. The composition of ruby and emerald is very similar, ruby is a complex of Al2O3 and chromium, emerald is a complex of Al2O3 and chromium containing Be, and garnet is an artificial stone, each with its own advantages and disadvantages, as described below. In terms of equipment acquisition, the purchase price of ruby and emerald lasers is high, and the above two types of lasers are only original imports, but no domestic ones. But the main thing is that the failure rate of both is relatively high, and the cost of maintenance and repair is very high, much higher than that of Nd:YAG laser, so the promotion of the equipment is limited by some economic conditions. Ruby laser is mainly suitable for Caucasians and is the best-selling laser in Europe and America, but in Asia and the mainland, where yellow people are the main population, it is prone to complications of pigment loss and has fewer users. The Emerald Laser is the best-selling laser in developed regions such as Korea, Japan and Taiwan. Therefore, it is not a question of which one is better or worse, but the target group is different between ruby and emerald laser. However, due to the price and other reasons, the early emerald laser only in the mainland after a short period of sales, then withdrew from the market, has not entered the mainland market, until the second half of 2009, with the rapid development of the mainland economy, the party began to re-enter, and really in the mainland market sales. The purchase price of Nd:YAG laser is relatively slightly lower, and domestic manufacturers are able to produce, such as domestic, the price is even lower, while its biggest advantage is that the failure rate is very low, maintenance and repair costs are far lower than the first two types of lasers, so it is the longest used in China, the best sales of laser. In terms of treatment effect, the Nd:YAG laser emits a wavelength of 1064nm, which is less selective for pigment, and its energy is absorbed by the pigment and also absorbed by the blood vessels, leading to the rupture of blood vessels and bleeding, so there will be obvious bleeding and thick crusting when treated with the Nd:YAG laser. However, because the energy is partially absorbed by the blood vessels, the treatment effect is reduced accordingly. The ruby and emerald lasers emit wavelengths of 694nm and 755nm respectively, which are very close to each other and have similar effects, except that the emerald laser is more suitable for yellow people. Both wavelengths are highly selective for pigmentation, and the blood vessels absorb very little, so there is no bleeding during the treatment, only local whitening and slight crusting at the treatment site, and the treatment effect is better than that of Nd:YAG laser.