The stunning eye makeup worn thousands of years ago by Queen Nefertiti and other Egyptian royals may not have been used to enhance beauty alone: New research suggests that the ancient cosmetics may have helped prevent or treat eye disease.

Some ancient Egyptians thought their lead-based black eye makeup could protect against illness. Until now, scientists haven't believed this because lead-based substances -- such as paint -- can make people sick.

In the study, published in the current issue of the journal Analytical Chemistry, researchers analyzed substances from ancient Egyptian makeup containers that are preserved at the Louvre museum in Paris. They found that the substances raise the production of nitric oxide in skin cells, which can help boost the immune system and prevent or treat eye infections.

According to study author Christian Amatore, of the Universite Pierre & Marie Currie, and colleagues, eye infections could develop due to exposure to contaminated water and may have commonly struck ancient Egyptians.

While it's not known if the makeup was specifically produced for health reasons, "it is clear that such intentional production remains the first known example of a large-scale chemical process," the study authors wrote.