A close-up of Leonardo da Vinci’s “Salvator Mundi.” (Christopher Tyler/American Medical Association)

For centuries, people have theorized about the source of Leonardo da Vinci’s artistic genius. Just how was he able to so accurately capture depth and perspective on a flat canvas?

New research suggests da Vinci’s unmatched talent may in part be the result of his ability to see the world differently — literally.

There is now evidence that da Vinci’s renowned capacity to reproduce the three-dimensional world in paintings may have been aided by an eye disorder that allowed him to see in both 2-D and 3-D, according to a study published Thursday in JAMA Ophthalmology, a peer-reviewed journal.

Da Vinci is believed to have had a condition called intermittent exotropia — commonly referred to as being “walleyed” — a form of strabismus, eye misalignment that affects about 4 percent of the U.S. population. Those with exotropia usually end up favoring one eye over the other, which means they are more likely to see the world as if it were, say, painted on a flat canvas.

“When they’re in that condition . . . they’re only seeing the world monocularly, with much reduced depth cues,” the study’s author, Christopher Tyler, a professor at City University of London and researcher at the Smith-Kettlewell Eye Research Institute in San Francisco, told The Washington Post. “The image they’re seeing is much closer to what they want to paint on the canvas.”

But in da Vinci’s case, the painter was, at times, able to control his wandering eye, which in turn provided him with an artistic advantage, Tyler said, noting that the ability to switch between the two perspectives meant that da Vinci would “be very aware of the 3-D and 2-D depth cues and the difference between them.”

Tyler, who has studied da Vinci’s life for more than 20 years, said he started noticing the disorder’s telltale sign while examining works by the artist and those done of him.

In many cases, “they had the eyes diverted,” he said.

“This is something I would notice, what I’m attuned to notice,” said Tyler, who specializes in studying binocular vision.


“David” by del Verrochio, full face. (Courtesy Christopher Tyler/American Medical Association)

Tyler set out to support his theory by conducting mathematical analyses on six works — two sculptures, two oil paintings and two drawings — believed to reflect da Vinci’s appearance. The pieces included Andrea del Verrocchio’s “David,” a bronze sculpture said to be a depiction of da Vinci as a youth, as well as da Vinci’s “Salvator Mundi,” which recently became the most expensive painting ever auctioned, selling for more than $450 million last year.

Measuring the relative positions of the pupils, irises and eyelids in each work, Tyler wrote in the study that da Vinci had “an exotropic tendency of approximately -10.3° when relaxed.”

“There’s a weight of evidence in all these portraits that tends to add up to something meaningful,” Tyler said.

Da Vinci would not be the first famous artist to have the disorder. Previous studies analyzing eye alignment in self-portraits have suggested that painters such as Rembrandt, Edgar Degas and Pablo Picasso were also strabismic.

Shira Robbins, a professor of ophthalmology at the University of California at San Diego who was not involved in the research, called Tyler’s findings “intriguing,” echoing his belief that the ability to switch between seeing out of one or both eyes “can be advantageous from an artistic perspective.”

“What happens in some people is when they’re only using one eye . . . they develop other cues besides traditional depth perception to understand where things are in space, looking at color and shadow in a way that most of us who use both eyes at a time don’t really appreciate,” said Robbins, who is also the educational director at the Ratner Children’s Eye Center within the Shiley Eye Institute in La Jolla, Calif.

But Robbins pointed out that there’s a “caveat” in the research — the “images are not 100 percent identifiable as being” da Vinci, she said.

Very few self-portraits of da Vinci exist, Tyler said, adding that he had to take “a more creative view” when identifying “likely portraits” of the famed artist.

While several of the works examined “have not generally been considered to be self-portraits,” the study said, “da Vinci himself was very clear that artists’ work is likely to reflect their own appearance.”

In the Codex Atlanticus, the largest set of da Vinci’s drawings and writings, he wrote that the soul “guides the painter’s arm and makes him reproduce himself, since it appears to the soul that this is the best way to represent a human being.”

If the works Tyler studied are in fact accurate reflections of da Vinci, Robbins said she would agree that the painter appeared to have strabismus.

The research, she noted, would have a “hugely positive” impact on the large number of people with eye-alignment disorders. The condition often leads to the misconception that people who have it are of “lesser intellect,” Robbins said, adding that research has shown those people often get passed up for jobs or aren’t as frequently invited to social gatherings.

“Anybody who has strabismus will look at this and be imbued to know that someone as brilliant as Leonardo da Vinci had a similar problem to them, and it certainly didn’t seem to hinder him in any way possible,” she said.

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