Study suggests Leonardo da Vinci's genius due to eyesight flaw

Salvator Mundi was among the works the researchers studied.

The brilliance of Leonardo da Vinci has been variously attributed to his meticulous attention to detail, his vast knowledge of art, science and optics, and the fact he painted with his left hand.

But new research has shown that an intermittent flaw in his eyesight may also have helped him perfectly capture three-dimensional form.

Professor Christopher Tyler, a visual neuroscientist from City, University of London, studied two sculptures, two oil paintings and two drawings that featured the artist - either in the form of a self-portrait or as the posing model.

They included Leonardo's Salvator Mundi, Vitruvian Man and the bronze statue of David by Andrea del Verrocchio, his teacher.

In each case, the alignments of the pupils in the eye apertures diverged by up to 13.2 degrees, suggesting Leonardo had a condition known as exotropia, where one eye looks directly at an object while the other gazes off to one side.

It is also known as stereoblindness and it prevents people from combining independent images from each retina to create depth perception.

However, the condition is thought to be useful for artists, as it allows them to view the three-dimensional world in two dimensions, and so replicate it on paper more easily than people trying to do the same with a three-dimensional view in front of them.

Writing in the journal JAMA Ophthalmology, Tyler said: "The presence of exotropia, particularly if it was intermittent, may have contributed to da Vinci's exceptional ability to capture space on the flat canvas.

"Intermittent exotropia is generally associated with good stereoscopic vision.

"This condition is therefore rather convenient for the painter, since viewing the world with one eye allows direct comparison with the flat image being drawn or painted."

About one in 10 people is thought to be stereoblind and the condition is often so subtle many people do not realise they have it. They are often also dyslexic.

The condition usually starts in early childhood when the muscles which keep the two eyeballs aligned fail to develop properly. As one eye focuses on the scene in front, the other drifts away and can lead to double vision until the brain gradually begins to suppress messages from the wandering eye.

The effect is similar to closing one eye, a technique used by many painters in an attempt to see the world in two dimensions.

Artists who are stereoblind are also thought to have a greater ability to focus on the shapes of objects and the "negative" space around them.

Recent studies have shown that a host of other successful artists had the condition, including Rembrandt, Gustav Klimt, Man Ray, Winslow Homer, Picasso, and Roy Lichtenstein.