Both sclerotherapy and long pulse ND-Yag are good treatment options. The clinical studies so far show that sclerotherapy is slightly more effective and may take fewer sessions.
However, sclerotherapy can be accompanied by risks such as allergic reaction, embolism and infection. These are almost unheard of with the long pulse laser. Long pulse ND-Yag also happens to be safe for all skin types, and is a good alternative for those who are afraid of needles, allergic to sclerosant or who have very small veins.
Hope this helps.
