When surgeons stopped trusting the color white

At the beginning of the 20th century, operating rooms were completely white.

White on the walls, on the lights, and on the gowns.

No one questioned that this was the cleanest environment possible. The surgeon has been operating for hours. His gaze is fixed on the intense red beating in front of him. But something starts to go wrong. He blinks. The red loses intensity. Greenish tones appear where they shouldn't exist. The edges blur. The blood loses definition. His vision becomes unstable just when he needs it most. He tries to force focus, but his eyes don't respond as they used to.

It's not physical fatigue; it's a biological limit that is starting to become evident.

Something has to change. This is a problem. And it will. From the 1910s and 1920s, operating rooms began to abandon absolute white and adopted greens and blues to compensate for the limitations of human vision, a necessary adjustment to overcome these biological restrictions.

What was happening?

After hours of looking at the same intense red against a practically white background, the problem wasn't with the blood... it was with the eye.

The human retina has three types of photoreceptors specialized in color perception: L, M, and S cones, sensitive to long (around 560 nm, red-orange), medium (around 530 nm, green), and short (around 420 nm, blue-violet) wavelengths, respectively. Under normal conditions, the signals from these three channels are processed by the visual cortex through an opponent-pair coding system (red/green and blue/yellow) that allows for precise discrimination of millions of chromatic nuances.

But in an old operating room, that balance was broken.

When the surgeon averted his gaze, the opponent-pair system continued to process information with partially saturated L cones. With the red signal suppressed, the green channel dominated unopposed, generating a post-adaptive illusion: the eye perceived greenish or cyanotic tones on neutral or white surfaces (the familiar complementary color afterimage), but also, and more problematically, a loss of contrast between tissues that are easily distinguished under normal conditions.

In the surgical environment, this distortion had direct practical consequences. The discrimination between arterial and venous blood, which depends in part on hemoglobin saturation, was compromised. The differentiation between well-perfused tissue and ischemic tissue, which manifests precisely in the red-pink spectrum, lost reliability. And all of this occurred gradually and, to a large extent, imperceptibly to the surgeon himself.

The result is a transient reduction in sensitivity in that spectral band, a phenomenon known as chromatic adaptation or selective cone fatigue.

Was this similar to color blindness? Not exactly. Color blindness is a permanent, usually genetic, alteration in one or more types of cones. What surgeons experienced was a temporary and reversible phenomenon: a functional fatigue that momentarily altered color perception but disappeared with rest or a change in the visual environment.

The problem wasn't that the eye couldn't see red. It was that, after a while, it stopped seeing it accurately and with green or blue tones.

 

How was the problem solved?

The solution was as simple as it was brilliant: change the color of the environment.

At the beginning of the 20th century, some surgeons began to replace the dominant white of the operating room with green and, shortly after, blue tones. It was not an aesthetic decision or a hospital trend. It was a practical response to a physiological limit.

Green and blue serve a very specific visual function. As they are colors opposite to red in how the brain processes chromatic information, they help compensate for the fatigue caused by prolonged exposure to blood. When the surgeon looks away from the surgical field and encounters green or bluish surfaces, the visual system regains some of its balance, and the appearance of reddish or greenish afterimages is reduced.

Additionally, these colors improve contrast. Instead of working surrounded by white that amplifies glare and makes red saturation more aggressive, the surgeon operates in a more stable environment for the retina, with less visual fatigue and a greater ability to distinguish nuances in tissues and bleeding.

This is how modern operating rooms, which seem normal to us today, were born.

Behind surgical green was not symbolism, but applied neurophysiology. A visual correction designed to compensate for the limitations of the human eye and allow precision to depend not only on the surgeon's endurance but also on an environment designed to help them see better.

Whose idea was it?

There was no sudden discovery or moment of revelation. It was a solution that emerged from practice when accumulated experience began to clash with the limits of the human body.

In the early 20th century, some surgeons began to question the absolute dominance of white in operating rooms. Among them, Harry Sherman, an American physician credited with introducing surgical green around 1914, stands out. He did so based on repeated observations: after long operations, his vision changed in ways he could not ignore.

Sherman understood that the visual environment directly influenced the surgeon's precision. By replacing white with green, he reduced L-cone fatigue, mitigated the accumulation of adaptive debt, and improved the ability to discriminate nuances in tissues during the most critical moments of an operation.

What began as an almost experimental adjustment gradually spread to hospitals worldwide, and over time led to the current pale green, surgical blue, or neutral gray scrubs that are ubiquitous in any operating room today.

It was a response to a physiological limitation that no one had systematically considered until then.

And if you ever find yourself in an operating room and you're not quite convinced by the color of your scrubs, or why the color of staff not in the operating room must change from those who are, remember that this discreet, seemingly arbitrary shade is there for a precise reason: to maintain stable chromatic perception for all healthcare personnel during the hours when it matters most.

That unassuming color, every day, helps save lives.

Infographic

FAQs. Frequently asked questions about the color of surgical uniforms

Why were early operating rooms completely white?

During the late nineteenth and early twentieth centuries, white was associated with cleanliness, sterility and control. In a period shaped by the fight against hospital infections, that color visually reinforced the idea of a pure and aseptic environment, although it was later found to be suboptimal for surgeons’ visual perception.

Why could red blood fatigue a surgeon’s vision?

Because prolonged exposure to intense red tones can temporarily reduce the sensitivity of L cones, the retinal cells most responsive to long wavelengths. In an almost entirely white environment, that contrast forced the visual system to operate under sustained chromatic load for hours.

What are L, M and S cones and what do they do?

They are three types of photoreceptors in the retina specialized in detecting different regions of the visible spectrum. L cones respond mainly to long wavelengths associated with red, M cones to medium wavelengths related to green and S cones to short wavelengths linked to blue. The combined output of these three channels builds normal color perception.

Was the visual alteration experienced by surgeons a form of color blindness?

No. Color blindness is usually a stable, often genetic condition that persistently affects one or more types of cones. What surgeons experienced was a transient and reversible shift in color perception caused by sensory fatigue after prolonged and intense stimulation.

Why did green and blue help solve the problem?

Because they reduced the visual impact of red and provided a more balanced environment for the retina. Being on the opponent axis of the red–green system, these colors helped counteract afterimages and improved perceived contrast after long exposure to blood, making it easier to distinguish tissues and fine details.

When did the color of surgical clothing and environments start to change?

The transition began in the early twentieth century and became established over the following decades. The American surgeon Harry Sherman is often credited with introducing surgical green around 1914, although adoption was gradual rather than immediate across hospitals.

How do greenish afterimages appear after looking at intense red?

They arise from chromatic adaptation and the opponent processing of color in the visual system. When the response to red temporarily decreases after prolonged stimulation, the relative signal of the opposing channel becomes more prominent and a greenish sensation can appear when shifting gaze to neutral or light surfaces.

What happens at the molecular level when L cones become fatigued?

The problem arises when one of these channels is subjected to prolonged and intense stimulation. The photopigments in L cones, the red-sensitive opsin also known as erythropsin or photopsin I, undergo a bleaching process. Continuous activation converts 11-cis-retinal into all-trans-retinal, temporarily depleting the pigment until the enzyme retinal isomerase regenerates it. The result is a transient reduction in sensitivity within that spectral band, a phenomenon known as chromatic adaptation or selective cone fatigue.

Does it still make sense to use green or blue in modern surgery?

Yes. Even though lighting, materials and surgical technology have improved significantly, human visual physiology remains the same. Using colors that reduce fatigue and enhance contrast is still beneficial in long and visually demanding procedures.

Are there other medical fields where color also affects visual performance?

Yes. Color choice can be relevant in radiology, endoscopy, microscopy and other fields where fine contrast discrimination and reduced visual fatigue are critical. In these contexts, visual design is not just aesthetic but an ergonomic tool grounded in neurophysiology.

References

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