Wearing compression stockings (thigh-highs) is imperative to achieving optimal results after sclerotherapy. They help keep the walls of the treated veins in close contact so that the body can break them down. If you do not wear them, the veins will fill back up with blood after the procedure and make it much less effective. I recommend that my patients wear compression stockings for a week after their sclerotherapy procedure, and that they wear them 24 hours a day (even in the shower). You can dry them with a hairdryer on cool settings after your shower. In terms of the pressure of the stockings, I recommend 30-40 mmHg (millimeters of mercury).
Hope this helps!