Asclera is a sclerosing agent that is injected into the vein. It works by damaging the endothelium, the inside lining of blood vessels. This causes blood platelets and cellular debris to attach to the lining of the vessels. Eventually, cellular debris and platelets cause the blood vessel to clot. Over time, the clotted vein will be replaced with tissue. is a prescription medicine that is used to treat two types of veins in your legs. • Uncomplicated spider veins (very small varicose veins ≤ 1 mm in diameter) • Uncomplicated small varicose veins (1 to 3 mm in diameter) known as reticular veins