Leonardo da Vinci described a contact lens as a possible way to correct eyesight.
In the Codex of the Eye, written around 1508, Leonardo proposed placing the eye in direct contact with water held in a glass vessel. He reasoned that changing the shape of the surface in front of the eye could alter vision, an insight related to the optical principle behind contact lenses.
His proposal was not a practical modern lens. The whole face or eye area would have had to interact with the water-filled apparatus, making it uncomfortable and difficult to use. Leonardo also did not produce a wearable lens suitable for everyday vision correction.
The idea is therefore best described as an early conceptual precursor. Modern contact lenses developed much later through advances in materials, manufacturing, and eye-care science.