Vision is an important tool when creating a painted artwork. Vision is used to survey a scene, guide the artist's movements over the canvas and provide feedback on the color and form of the work. However, it's possible for disease and disorders to alter an artist's visual perception

There is a long history of scientists and clinicians arguing particular artists were affected by vision disorders, based on signs in their works. Some argued the leaders of the Impressionist movement were short-sighted, for instance, and that their blurry distance vision when not using spectacles may explain their broad, impetuous style.

Supporting evidence of such disorders and their influence on artworks is often speculative and hampered by a lack of clinical records to support the diagnosis. A particular challenge to verifying these speculations is that artists are, of course, free to represent the world in whatever fashion they like.

So, is a particular style the result of impoverished vision, or rather a conscious artistic choice made by the artist? Here are three artists who it has been claimed suffered vision impairments.

Claude Monet

Elsewhere, the influence of eye anomalies in artworks is more compelling. Cataracts are progressive cloudiness of the lens inside the eye, producing blurred and dulled vision that can't be corrected with spectacles.

Cataracts are often brown, which filter the light passing through them, impairing color discrimination. In severe cases, blue light is almost completely blocked.

Claude Monet was diagnosed with cataracts in 1912 and recommended to undergo surgery. He refused. Over the subsequent decade, his ability to see critical detail reduced, as is documented in his medical records.

Importantly, his color vision also suffered. In 1914, he noted how reds appeared dull and muddy, and by 1918 he was reduced to selecting colors from the label on the paint tube.

The visual impact of his cataracts is demonstrated in two paintings of the same scene: the Japanese footbridge over his garden's lily pond. The first, painted ten years before his cataract diagnosis is full of detail and subtle use of color.

In contrast, the second – painted the year before his eventually relenting to surgery – shows colors to be dark and murky, with a near absence of blue, and a dramatic reduction in the level of painted detail.

There is good evidence such changes were not a conscious artistic choice. In a 1922 letter to author Marc Elder, Monet confided he recognized his visual impairment was causing him to spoil paintings, and that his blindness was forcing him to abandon work despite his otherwise good health.

One of Monet's fears was that surgery would alter his color perception, and indeed after surgery, he complained of the world appearing too yellow or sometimes too blue. It was two years before he felt his color vision had returned to normal.

Experimental work has confirmed color perception is measurably altered for months after cataract surgery, as the eye and brain adapt to the increased blue light previously blocked by the cataract.

Clifton Pugh

In addition to eye disease, color vision can be altered by inherited deficiencies. Around 8% of men and 0.5% of women are born with abnormal color vision – sometimes erroneously called "color blindness."

In one of its most common severe forms, people see colors purely regarding various levels of blue and yellow. They can't distinguish colors that vary only in their redness or greenness, and so have trouble distinguishing ripe from unripe fruit, for example. It has been argued no major artist is known to have abnormal color vision. But subsequent research argues against this.

His abnormal color vision is well documented in biographical information. Owing to the inherited nature of color vision deficiencies, researchers were able to test the color vision of surviving family members to support their case that Pugh almost certainly had a severe red-green color deficiency.

But an analysis of the colors used in Pugh's paintings failed to reveal any signatures that would suggest a color vision deficiency. This is consistent with previous work, demonstrating it was not possible to reliably diagnose a color vision deficiency based on an artist's work.