Time-out for your eyes: especially working in front of a screen is exhausting for the eyes. Pick a point in the distance and let your eyes wander a few minutes without fixing anything. This will help to relax and recharge your batteries.
Swelling under the eye often is a result from accumulation of water, so avoid too salty and spicy food and too much alcohol.
Particularly in the evening, generously apply some cream on the eye area and incorporate the temple and cheekbone expression lines appear especially early in this area.