Portal de Periódicos da CAPES

Color blindness in the medical workplace

2019; Wiley; Volume: 127; Issue: 4 Linguagem: Inglês

10.1002/cncy.22127

1934-6638

Bryn Nelson,

Retinal Imaging and Analysis

Yaw Owusu knows that stop- lights and the flag of his native Ghana include the colors red, yellow, and green. Yet until recently, the third-year medical student at Morehouse Medical School in Atlanta, Georgia, sometimes perceived the red as green. In college, he once flubbed a biology assignment because he could not distinguish between the 2 colors. In addition, in his histology course, he sometimes had to resort to using cues other than color, such as shapes, sizes, and densities, to help to identify pathologies on stained slides. Owusu, like an estimated 1 in 12 men and 1 in 200 women, has a form of color vision deficiency commonly known as color blindness. In one subtype called deutan color blindness, the retina’s medium cones are less sensitive to green and other medium wavelengths of light and are overly sensitive to some other colors. In protan color blindness, the retina’s long cones are similarly impaired in their ability to detect red light and other long wavelengths. Much of the trouble derives from excessive overlapping between red and green cones, which causes normally distinct colors to become nearly indistinguishable. When his classmates surprised him on his birthday in 2018 with a pair of glasses that filter out some of the overlap (made by the Berkeley, California–based company EnChroma), Owusu’s surroundings began to settle into clearer colors. “When I wore the glasses I was like, ‘Whoa, this red really looks red! And it looks very different from this green,’” he says. “That was the element of surprise for me. So that definitely builds confidence.” Color blindness can pose major challenges for physicians, researchers, and technicians, some of whom have reported difficulty in interpreting color-coded charts, test strips, histological stains, and changes in body color indicative of pallor, jaundice, or cyanosis. The common nature of color vision deficiency has spurred vigorous debates over how to address the condition in the medical field. It has also spurred a recent burst of efforts to accentuate color differences in ways that might resonate across multiple areas of medicine. Emily Clarke, MBBS PG Cert(HR), a histopathology registrar and academic clinical fellow at Leeds Teaching Hospitals NHS Trust and the University of Leeds in the United Kingdom, says that color blindness has contributed to the ongoing debate over the importance of color in pathology. “The practice of pathology, as with pretty much all of medicine, is pattern recognition,” Clarke says. For pathology, that pattern recognition relies heavily on visual cues, although the cues extend beyond color and include the texture, contrast, structure, architecture, and other elements of an image. “When we’re training in pathology, you just put all of those bits of information together,” she says. Jeffrey Siegelman, MD, an associate professor of emergency medicine at Emory University in Atlanta, says that his color blindness was particularly apparent in medical school histology and pathology courses, just as Owusu’s was. Dr. Siegelman similarly adapted and developed workarounds by relying on other visual cues. “But there were some stains that I just wasn’t going to be able to see,” he says. Dr. Siegelman recently sought out a pair of EnChroma glasses after researching his deutan color blindness, which has impaired his ability to detect not only greens and reds but also some shades of orange, purple, brown, and other colors. Pathologists can make the right diagnosis without color cues in many cases, Clarke says, and colorblind pathologists have done well in the field. “And so it’s arguable: Does color really matter if they are able to practice and do a very good job? And I think that’s a reasonable argument,” she says. However, it does not make color extraneous, at least in the view of her research group, led by Darren Treanor, MB BCh, PhD, FRCP, a consultant pathologist at Leeds Teaching Hospitals NHS Trust. Clarke and Dr. Treanor made their case in a recent review of the importance of color to digital pathology.1 “The more information you get from the color in combination with other features, it can only be of benefit, really,” Clarke says. The extra information, they believe, is critical for diagnoses involving differentiation among subtle color differences, such as the assessment of dysplasia within colorectal polyps. A separate group of UK researchers found that color vision–deficient physicians did significantly worse than their counterparts with normal vision when they were asked to outline abnormalities, including a skin rash, fresh blood in stool or vomit, and the location of Bacilli bacteria on a stained slide.2 To get a better sense of how color blindness is perceived by practicing anatomic pathologists, researchers at the Mayo Clinic in Rochester, Minnesota, recently began soliciting responses to an anonymous 11-question survey. Dr. Siegelman says that his color blindness has complicated some of his own work in the emergency department, including looking for blood in stool samples and identifying red skin, eardrums, and throats. To compensate, he asks a nurse to help him mark out areas of redness. “I know that I’m not going to get it just right, so that’s my usual practice: to ask for help,” he says. In collaboration with EnChroma, Dr. Siegelman is now planning to test the glasses in clinical settings. “We’re going to start with a feasibility study: What is it like for clinicians to wear these glasses in the emergency department?” he says. Eventually, he hopes to test whether the glasses can improve physicians’ ability to see some red-hued clinical signs. Don McPherson, PhD, EnChroma’s cofounder and chief scientist, says that some users who have worn the glasses for a while have reported improvement in their color perception even without the glasses on, and this raises questions about the extent to which the brain can be “retrained” with new visual stimuli. In the meantime, both researchers at EnChroma and other researchers, including a group at the University of Birmingham in the United Kingdom, are working to create a similarly acting contact lens that uses a dye to absorb a band of light to help correct some of the overlap in green-red visual processing. Dr. McPherson says that his company has developed a filtered light source that operates in much the same way. Even individuals who are not colorblind can perceive colors differently, Clarke says, and pathology’s multistep hematoxylin-eosin staining process can lead to notoriously wide variations in the amount of pink and purple hues retained on slides. As the field moves toward digital slides, she says, the digital scanners, computer display monitors, and viewing programs can introduce even more color variability. Clarke and her colleagues are focusing on ways to mitigate the problem by calibrating and standardizing slide digitization. For one recent study, they designed a color-calibration slide that mimics stained tissue and can help to correct color variation introduced by the scanner.3 Researchers at the University of Heidelberg in Germany, meanwhile, are working to optimize the color contrast of digital slides. Eventual solutions could lead to color maps that are personalized for individual pathologists’ visual systems, and this is something that could aid colorblind physicians as well. “This is one of the many, many benefits of digitization,” Clarke says. “Histological stains, at the moment, are shackled to light microscopy. And now that we digitize, we can do whatever we want to the image to improve people’s perception.” Dr. Siegelman says that his new glasses, as he has become accustomed to them, have gradually made colors more vibrant across the spectrum. Also, from painful recent experience, he noted that the glasses clearly enhanced the redness of his thumb after he hit it with a hammer. “I can tell you personally that I had a red thumb and it was certainly redder with the glasses on,” he says with a laugh.