Leonardo da Vinci, Salvator Mundi (detail), c.1500, oil on walnut, 66 x 45 cm. Courtesy: Christie’s, London / New York

A new study, published in the journal JAMA Ophthalmology, claims that the secret behind Leonardo da Vinci’s genius was a rare eye disorder, which helped the legendary painter and polymath to capture complex three-dimensional scenes in his artworks.

A researcher from City University of London’s Optometry and Vision Sciences School has taken measurements from portraits by Da Vinci which are believed by some to have been modelled on the artist himself. The study concludes that the artist had strabismus, based on the distinctive eye alignment seen in the paintings. Works studied include Vitruvian Man (c.1490), St John the Baptist (1513–16), and the recently auctioned Salvator Mundi (c.1500).

The vision disorder, in which one eye looks away while the other focuses in on an object, has been suggested as an advantageous trait for artists, allowing them to concentrate on close, flat surfaces. Da Vinci is in good company – the condition has been diagnosed in other famous artists, including Rembrandt, Albrecht Dürer, Edgar Degas and Pablo Picasso.

Neuroscientist and author of the study Christopher Tyler said: ‘The condition is rather convenient for a painter, since viewing the world with one eye allows direct comparison with the flat image being drawn or painted.’ The disorder, Tyler says, ‘would perhaps explain da Vinci’s great facility for depicting the three-dimensional solidity of faces and objects in the world and the distant depth recession of mountainous scenes.’