Cross-eyed Leonardo

Not long ago, I wrote a post about the diagnoses of poor Mona Lisa, Feed Lisa Some Stake, whom the researchers could not leave alone and saddled Gioconda with multitude of health problems. Recently, scientists turned their attention to the master himself, Leonardo da Vinci.

Professor Christopher W. Tyler, PhD, DSc of City University of London, published an article Evidence That Leonardo da Vinci Had Strabismus in the journal JAMA Ophthalmology.

Key Points

Question  Did Leonardo da Vinci, the preeminent artist-scientist of the Italian Renaissance, have a form of strabismus that could have facilitated his artistic work?

Findings  Examination of 6 likely portraits and self-portraits of da Vinci in which the direction of gaze of each eye is identifiable shows that most paintings exhibit a consistent exotropic strabismus angle of −10.3°, supported by a similar Hirschberg angle in the recently identified da Vinci painting Salvator Mundi.

Meaning  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.

Abstract

Importance  Strabismus is a binocular vision disorder characterized by the partial or complete inability to maintain eye alignment on the object that is the target of fixation, usually accompanied by suppression of the deviating eye and consequent 2-dimensional monocular vision. This cue has been used to infer the presence of strabismus in a substantial number of famous artists.

Objective  To provide evidence that Leonardo da Vinci had strabismus.

The researcher analysed eyes in six pieces of art thought to be based on da Vinci: David (Andrea del Verrocchio); Young Warrior (Andrea del Verrocchio); Salvator Mundi (da Vinci); Young John the Baptist (da Vinci); Vitruvian Man (da Vinci).

Professor Tyler fitted circles and ellipses to the pupils, irises, and eyelid apertures on the artwork and then measured the relative positions of these features.

He found that there was evidence of strabismus in all six pieces of work.

In this diagram, the degrees of optical axial angles of the left and right eyes of all the studied characters of paintings and sculptures are shown, and the difference between them just shows a slightly stronger deviation of the left in almost all cases. And this, according to Tyler, can serve as evidence of the divergent squint of da Vinci. Well, maybe…

Indeed, such an eye position significantly improves stereoscopic vision and the ability to see spatial depth. “The first thing to consider is whether the objects have the necessary contrasts corresponding to their [three-dimensional] position,” Leonardo wrote in his Treatise on Painting.  Leonardo was one of the first artists to incorporate three-dimensionality into his work. It seems very likely, is it not, that the cause of this brilliant innovation is physiological.