01A hollow (tear trough) that casts a shadow
Where the lower lid meets the cheek, a groove forms when volume thins. The dark colour is a shadow, not the skin itself.
How a doctor tellsThe doctor shines light from the front. If the darkness fades when light fills the groove, it is mostly shadow.
02Under-eye fat bulging forward (eye bags)
The fat around the eye can push forward as the tissue holding it weakens. The bulge casts a shadow below it, so it looks like a hollow too.
How a doctor tellsYou will be asked to look up. If the bulge gets bigger, it is fat, and adding filler underneath can make it look puffier.
03Brown pigment
Some people, especially with darker or Asian skin, have brown colour in the skin under the eye, often made worse by rubbing and sun.
How a doctor tellsGently stretching the skin does not make brown pigment disappear. It looks the same in every light.
04Thin skin showing blood vessels
Very thin skin lets the blue or purple of vessels and muscle show through, often worse when tired.
How a doctor tellsPressing lightly makes the colour fade briefly. It looks bluish rather than brown.