China's idiom is actually an abnormal phenomenon of eye metabolism. When people get old, their eyes are more likely to produce conjunctival pigmentation and become turbid and yellow. People are not valued when they are old, especially women, which also means that they are useless when they are old.

When using it, if "beauty is dying, people are getting old", then the pearls here are pearls, but only old pearls are possible, and some people will use it to ridicule older women they don't like and say that they are getting old.

The reason why people get old:

There is a thin transparent film on the surface of human eyeball, which is called conjunctiva. After being polluted by ultraviolet rays and dust for a long time, there will be adverse reactions of pigmentation.

Pigments gather in the conjunctival layer to form a large area of macula. A slightly raised dark yellow substance appeared on the surface of white eyeball, and the black eyeball became more turbid. Human beings have been stimulated by the external environment for a long time, and the elderly are more likely to produce conjunctival pigmentation, so there is a saying that "people are old and yellow."