What is CLaCS?

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You may have, heard of, or seen your relatives and friends having dark purple or blue bulging, twisted veins on their arms and legs – these are varicose veins. Usually, they happen to someone who sits down or stands up without moving for a long period of time, and to older and pregnant people. Varicose veins are caused by blood pooling in the legs due to poor venous circulation, which is a result of valves in the veins becoming weakened and unable to function properly. Someone with varicose veins will experience a burning or aching pain and heaviness in their legs. They may also feel itchiness around the affected veins. [1] A milder version of varicose veins, spider veins, are redder, thinner and usually cause less pain and discomfort than varicose veins do. Many people who have varicose veins wish to opt for treatment as it is a cause for cosmetic concern for them.

There are a number of surgical treatment options available, and one such treatment is CLaCS (Cryo-Laser and Cryo-Sclerotherapy), a minimally invasive procedure which causes little scarring. It was invented by Prof Kasuo Miyake, a vascular surgeon, in 2002. One advantage it has over most traditional surgical procedures is that the patient is able to resume their daily life only a few hours after it is finished, and are not required to stay overnight for observation. It combines the effects of both laser therapy and sclerotherapy to achieve the best results, all while the skin is cooled with a special device to make it almost painless.

CLaCS treatment being performed. Taken from OneHealth.

CLaCS treatment is mainly aesthetic, suited for those who wish to treat thinner and smaller varicose veins. It is famous for its capability to allow surgeons to locate shallower veins, which are not as visible through the usual imaging modalities such as ultrasound. For people who seek treatment for varicose veins because it causes them pain, their condition would usually be more severe and a phlebectomy or radiofrequency ablation would be more effective than CLaCS.


The aim of CLaCS treatment is to burn off the faulty and damaged veins and promote flow of blood through the healthy veins. After the veins are closed off and shrunk, blood will flow through other healthy, working veins and not pool in the faulty veins anymore. Standard CLaCS treatment comprises 4 segments:

  1. Skin Cooling

-20℃ air is blown on the skin throughout the procedure to cool it (hence the ‘cryo’ included in the name, which means to freeze.) This reduces any pain or discomfort from the laser and sclerotherapy and protects the skin. If a patient’s skin is deemed to be particularly sensitive, a numbing cream can be applied an hour before the procedure as well. [2]

  1. Augmented Reality

An augmented reality device uses infrared light to make the skin brighter, then the camera attached to it will capture an image of what the veins look like under the skin. This infra-ray scan will then be projected onto the skin itself so that the locations of veins which are too shallow and thin to be detected by ultrasound can be clearly seen. [3]

  1. Laser Treatment

A transdermal laser is used to burn off the targeted veins so blood can no longer collect in them and cause further swelling. The light and heat energy is aimed at the vein to damage the inner vessel walls. The wavelength of the laser’s energy ensures that the skin is minimally affected, as it is absorbed more by the blood vessels.

  1. Sclerotherapy (Injection)

A mild sclerosant (medicine) will be injected into the burnt vessels to shrink them further, ensuring that spider veins will not resurface at that area. Because of its lower potency, the danger of it causing anaphylaxis or other adverse reactions is very low.

After undergoing the CLaCS procedure in Singapore, you should be able to resume daily activities within 4-6 hours. It will most likely take around 1-2 months for the dark veins to disappear completely, and do not be alarmed if you find that they become darker the first week after the procedure, because this is a normal occurrence. It should be noted that although there is a very little chance of spider or varicose veins resurfacing at the treated area, they may however appear on other parts of the body after the procedure.


CLaCS is a fairly new treatment method for varicose veins, and as of now, within Asia, is only available in a few countries. Our vascular interventional centre is currently the only clinic in Singapore to offer the option of CLaCS treatment. Feel free to book an appointment with our specialists, Dr Benjamin Chua and Dr Chen Min Qi today if you would like to opt for CLaCS Singapore to treat your varicose veins.

Contact us with the details below:

+65 6694 6270 (Call)
+65 9898 3595 (WhatsApp)
[email protected] (Email)

Novena Specialist Centre #06-08, 16-19
8 Sinaran Drive, Singapore 307470

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