Venous leg ulcers, sometimes called varicose or stasis ulcers, are a consequence of damage to the valves in the veins of the legs, leading to raised venous pressure. Venous ulcers are characterised by a cyclical pattern of healing and recurrence. The main treatment is the application of compression, either in the form of compression bandages or hosiery. Dressings are usually applied beneath the compression to aid healing, comfort and to control exudate. Wounds heal quicker in a moist environment and dressings are used to absorb excess fluid or retain fluid in an otherwise dry wound in order to achieve a 'moist wound environment'. There are a large number of dressing products and types available. It is unclear whether particular dressings aid healing of leg ulcers.