What causes thread veins and are they curable?

Vein valve failure: Thread or spider veins, also known as telangiectasias arise from increased pressure transmitted from larger veins in the dermis. One way valves which control venous pressure fail, resulting in venous hypertension. While not technically curable, they are easily treatable and controlled, mainly with sclerotherapy injections.

Many causes: There is no cure to prevent spider veins but once you have them they can be treated by sclerotherapy or lasers.

Sclero or laser.: Spider veins get their name because they look like spider legs. The short answer is that topical laser or sclerotherapy usually works well. The longer answer is that if you have many spider veins and/or combinations of spiders, reticulars and varicose veins then you should first have a venous reflux exam. You should see a vein specialist.