To conceal dark eye circles, use a proper concealer. Test out the best appropriate colors. When you choose a concealer, choose a lighter color.
Try using vitamin K-based eye care products. Vitamin K eye cream can help strengthen capillary walls, so dark circles and veins become less visible.
If you have chronic dark circles, laser treatment can be an option. Lasers can thicken the skin, by increasing collagen production, so you are less likely to see veins. Because the skin around the eyes is very thin, you will also need sunscreen to protect it.