Can varicose veins exist but not be visible?

Most varicose veins — gnarled, bluish veins just under the skin's surface — result from problems with deep veins inside the leg. The surrounding muscles and one-way valves in the deep vein weaken, a condition called venous insufficiency. The same process can occur in the deep veins without varicose veins being visible, especially when a person is lying down or elevating their legs.