CO -The lowest degree in severity, means that there is no sign of venous disease when looking at the leg

C1 – Means that the person has spider or reticular veins when looking at the leg

C2 – Means that varicose veins are present when looking at the leg

C3 – Denotes the presence of edema (swelling) of the ankle.

C4 – Includes pigmentation (darkening) of the skin, eczema (redness, itching), lipodermatosclerosis (hardening of the soft tissues), and atrophie blanche (a whitish skin area)

C5 – Means that a healed venous ulcer is present when looking at the leg

C6 – The most severe category, means that an active open venous ulcer is seen on the skin