When the Bully Is a Doctor

https://www.nytimes.com/2018/06/14/well/live/doctor-bully-bullying.html?partner=rss&emc=rss

Bullying among health care workers is far more common than we acknowledge.

Artists Who Lose Their Vision, Then See Clearly

https://www.nytimes.com/2018/06/19/arts/design/macular-degeneration-serge-hollerbach-david-levine.html?partner=rss&emc=rss

Eight artists found new ways to see after learning they had macular degeneration. “Nothing to lose is a kind of new freedom,” says one of them.

Human Retinas Grown In A Dish Reveal Origin Of Color Vision

https://www.npr.org/sections/health-shots/2018/10/11/656560767/human-retinas-grown-in-a-dish-reveal-origin-of-color-vision?utm_medium=RSS&utm_campaign=news

In order to see the red of a sunset or the green of spring leaves, developing human eyes need to get the right hormone at the right time.

That’s the finding of a team of scientists who studied how color vision develops using hundreds of human retinas grown in the lab.

The discovery, published Thursday in the journal Science, could help accelerate current efforts to cure colorblindness. It could also lead to new treatments for diseases including macular degeneration, the leading cause of vision loss.

“It’s important that we understand how nature controls the development of the retina so we can understand better why things go wrong in disease and how we can treat them,” says Steven Becker, a scientist at the National Eye Institute. The newly published findings are a step in that direction, says Becker, who has no connection to the research.

The development of color vision in people has been difficult to study because it usually occurs in the womb — and out of sight. But two scientists at Johns Hopkins University thought they might find some answers using retinas grown in the lab.

These “retinal organoids” have been around for a few years but are difficult and tedious to grow, says Kiara Eldred, a graduate student at Hopkins who is the paper’s first author.

It takes up to a year to turn a batch of immature retinal cells into a functioning organoid.

“For the first week of their life, I take care of them every day,” Eldred says. After a couple of weeks, she says, the cells become “a little bit more independent.”

Credit: Johns Hopkins University

And with luck, these clusters of immature cells develop into a 3D structure that “looks and acts like a developing retina that you would see in a baby,” says Bob Johnston, Eldred’s boss and an assistant professor in the biology department.

Johnston’s lab had been studying vision in flies. But he and Eldred saw a chance to try something much more ambitious.

“We discussed this crazy idea of: Could we use these human retinal organoids to study how we get the different color-sensing cells in our eyes?” Johnston says.

Using human cells was key because you can’t study how humans see color in a fly, or even a mouse.

“Mice don’t sense red,” Johnston says. “They don’t have these red-detecting cells. So we really have to study this in human tissue to get any insight into how it works.”

Johnston and Eldred knew that in a human fetus, cells that detect blue light appear first. Then come cells that respond to red and green light.

And research on animals suggested that the thyroid hormone was involved in the development of these color-sensing cells, called cones. So Johnston had Eldred conduct an experiment with immature retinal cells.

“I added thyroid hormone to the dish during their development, and we got more red-green cones developing in those organoids,” she says. “We got really excited because we were on to something.”

It would take years and many more experiments to confirm that the thyroid hormone was actually triggering the emergence of color vision. And the team still hasn’t figured out what causes some cones to go on to become even more specialized by detecting only red or only green.

But Johnston says his lab is now preparing to take on two new goals.

“One is to restore color vision to people that are colorblind,” he says. What his lab is learning, he says, could help speed an existing effort to use gene therapy to cure colorblindness.



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The lab’s second goal is to use retinal organoids to better understand diseases including glaucoma and macular degeneration, a leading cause of vision loss.

Macular degeneration affects the macula, an area of the retina that provides high-resolution vision. The condition has been hard to study, though, because mice don’t have a macula.

So Johnston hopes to learn more by having his lab create macular organoids.

There’s growing optimism among scientists that new treatments for retinal diseases will emerge from such efforts, Becker says. Initially, he says, researchers had doubts about whether a retina grown in a dish could mimic the real thing.

But studies like this one on color vision, he says, “show that the similarity is quite high.”

To encourage scientists to develop more retinal organoids, the National Eye Institute is sponsoring a scientific competition with $1 million in prizes.

Strabismus May Have Helped da Vinci Express His Genius

Leonardo da Vinci may have had a form of strabismus, or eye misalignment, that helped him create masterpieces such as the Mona Lisa, Vitruvian Man, and Salvator Mundi, the author of a new study writes.

The evidence suggests that da Vinci had intermittent exotropia, Christopher W. Tyler, PhD, DSc, writes in an article published online October 18 in JAMA Ophthalmology. With exotropia, one eye turns slightly outward, which may have enhanced the artist’s ability to render 3-dimensional objects on a 2-dimensional surface, Tyler suggests. “This would perhaps explain his great facility for depicting the 3-dimensional solidity of faces and objects in the world and the distant depth recession of mountainous scenes.”

It is likely that other great artists, including Rembrandt van Rijn, Pablo Picasso, Edgar Degas, Giovanni Francesco Barbieri, and Albrecht Dürer, also had strabismus, as determined by studying their self-portraits, adds Tyler, a visual neuroscientist in the Division of Optometry and Vision Sciences, School of Health Sciences, City University of London, United Kingdom.

Da Vinci, however, presented a more challenging case because few life portraits of him exist.

Lacking definitive attributions of da Vinci’s likeness, Tyler looked for evidence of strabismus in six “candidate images”: two sculptures, two oil paintings, and two drawings. All are works for which da Vinci is thought either to have projected parts of his own appearance or served as a model. “Strabismus was assessed by fitting circles and ellipses to the pupils, irises, and eyelid apertures images identified as portraits of Leonardo da Vinci and measuring their relative positions,” Tyler writes.

Measurements from the six works yielded a mean optic axis angle estimate between the right and left eyes that was consistent with a diagnosis of intermittent exotropia (t5 =2.69; P = .04, 2-tailed), with a mean exodeviation of -10.3o.  These findings suggest that da Vinci may have had an exotropic tendency of approximately -10.3o when relaxed, but could have reverted to orthotropia when concentrating on his work.

With intermittent exotropia, da Vinci would have been able to switch from binocular to monocular vision at will, Tyler concludes. “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.”

Tyler has disclosed no relevant financial relationships.

JAMA Ophthalmol. Published online October 18, 2018. Abstract

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