Speculation that the “Mona Lisa” was made possible by the inability of Leonardo da Vinci to see straight, well, let me just say that the theory certainly caught my eye. Not only am I an artist who has spent my entire adult life trying to capture the Maine Woods and the cityscapes of Boston and Rome, but I also just had cataract surgery on both eyes. I’m about to find out, at age 72, whether better vision makes me a better painter.

The report, by Alex Matthew-King, was in the Independent newspaper. It covered a study suggesting that Leonardo may have suffered from strabismus, a difficulty in getting the two eyes to align correctly when looking at an object. The diagnosis is based on analysis of a Verrocchio sculpture for which Leonardo may have modeled, a self portrait drawing in old age, and other renderings of the head by the Italian master.

Professor Tyler notes the phenomenon that artists tend to paint faces that look like themselves. He quotes Leonardo as suggesting that it is the soul that “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.” Mr. Tyler suggests that it was Leonardo’s strabismus had caused him to unconsciously imbue various self portraits with the misalignment of his own eyes.

I’m not entirely convinced by this line of thinking. Leonardo, after all, also cautioned young artists to avoid the tendency to draw all figures to resemble their own features, even if this is a natural impulse, or the result of learning to draw portraits from studying one’s own features in the mirror. He also warned against the related fault of making all the figures in a painting seem more like brothers than distinct individuals.

This business about Leonard is also undermined by “The Squinter.” That’s the nickname of Giovanni Francesco Barbieri, who is known in immortality as Guercino. His crossed eyes can be clearly seen in his 1635 self-portrait. One would think if Leonardo couldn’t conquer his strabismus, then The Squinter would have the same problem. Yet, amazingly, there is no population of cross-eyed figures in Guercio’s vast oeuvre.

The diagrams excerpted in the article from Professor Tyler’s article purporting to show strabismus in the Verrocchio sculpture and Leonardo’s painting of the Young St. John the Baptist are striking displays of distortion. The symmetrical, two dimensional almond shapes of the diagram, though, fail to correspond to the true margins of the eyelids. One has to look closely to perceive all this, but feature the following.

The lids, correctly visualized by Leonardo, are not symmetrical, but flatter on the bottom, more rounded on the top — with the high point of each lid closer to the inside margin of the iris. Leonardo also perceives that the inside corners of the eye are more forward and the outside corners more to the rear. This is because of the way the eye socket is cut away at the side. Every artist learns that the eyelids are highly three dimensional and difficult to put into perspective.

Feature what Bernard Berenson called “the most beautiful drawing in the world. “ That’s Leonardo’s silverpoint of a study for The Virgin of the Rocks. It certainly is arresting. When the girl’s head is turned to one side, with the eyes still looking at the viewer, the white of the more distant eye is more foreshortened and narrower than that of the nearer eye. The lid of the near eye is more perpendicular, the far lid more foreshortened.

Wait, though. If one looks at the near iris, and imagines the circumference of the whole eyeball around it — and does the same for the far eye — one discovers a much larger eyeball is needed for the eye on the right than the left. Which suggests that Professor Tyler may be onto something after all. So I followed Leonardo’s own advice to artists and took a reproduction of the drawing to a mirror and looked at it in reverse.

Leonardo recommends this technique to illuminate the faults in a drawing. Lo, the drawing did look more distorted in the mirror. Not by much, though. I am more disturbed by the difference in the size of the two pupils. Since Leonardo has many drawings of heads which do not manifest this strabismus, I am willing to chalk it up to expressive license — and give Professor Tyler credit for a subtle intuitive diagnosis, unfairly exaggerated in his diagrams — his own kind of strabismus.

Mr. Babb, an artist who is a master of cityscapes and forests, maintains his studio at Sumner Maine and is represented by Vose Galleries of Boston.

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Image: “Study for the Virgin of the Rocks,” Leonardo Da Vinci. Royal Library, Turin. Via Wikipedia.