The phenomenon where under-eye hollows appear more pronounced during a smile is related to facial muscle activity and the underlying structural changes that occur with age. When a person smiles, muscles around the eyes, particularly the orbicularis oculi, contract. This contraction can redistribute the soft tissues and fat pads in the lower eyelid and cheek area, causing them to shift and potentially accentuate any existing shadows or depressions beneath the eyes. Consider an analogy: pressing on a water balloon at one point causes the liquid inside to shift, potentially creating bulges or depressions elsewhere.
The prominence of this effect is influenced by several factors, including age, genetics, and skin elasticity. As individuals age, the skin loses collagen and elastin, leading to reduced support for the underlying tissues. This can result in the descent of cheek fat pads and the formation of deeper tear troughs. Consequently, the muscle contraction during smiling can have a more significant impact on the appearance of under-eye hollows. Furthermore, genetic predispositions can influence the natural structure of the face, making some individuals more susceptible to this effect than others. The perceived depth of these hollows can also be influenced by lighting conditions and the angle at which the face is viewed.