The heavy eye make-up favoured by ancient Egyptians such as Cleopatra may have had medical as well as aesthetic benefits, French research suggests.
The study, published in the journal Analytical Chemistry, suggests it helped to protect against eye disease.
The key appears to be lead salts contained in the make-up.
At very low levels, salts produce nitric oxide, which boosts the immune system to fight off bacteria which can cause eye infection.
The make-up used by the ancient Egyptians to darken and enhance the eyes sometimes took up to a month to concoct.
In theory, because it contained lead it might actually have posed a risk to health.
But an analysis by scientists from the Louvre Museum and the CNRS research institute found that in very low doses lead could actually have a positive effect.