Week in Review: Number 16

In the News: Special Edition 1
Thank you to Optometric Physician  for this piece. While I am neutral to both sides of politics, I very much enjoyed watching the congressman speak. I imagine that for his doctors, this congressman and former Navy Seal must be a great pleasure to work with as he takes steps toward a complete recovery.

Excerpt:
The other day I stumbled upon a YouTube video of Congressman Dan Crenshaw by chance. Crenshaw, for those who don’t know, is a former Navy Seal who lost an eye to an IED while serving in Afghanistan. What I didn’t know was that his other eye was severely damaged and recently required surgery for retinal detachment repair.

Regardless of your politics (which I don’t want to hear about), as a human being, fellow American and as an OD, I think you will be touched by Crenshaw’s humility and inner strength as he describes his ordeal and the impact it’s had on his life. Particularly poignant was his description of his vision both before the detachment when he was aphakic and now, as he waits for a gas bubble to dissipate before seeing the success or failure of the surgery. I sensed only determination and grace in his words and calm demeanor, but I was overcome with the magnitude of what he faced. I was also thankful for his service and sacrifice for our country.

Hearing Crenshaw’s words made me think about what we do every day and how important vision is, especially when one faces the prospect of life without sight. I was moved by the interview and urge you to take a moment to listen to it. For Rep. Crenshaw, I will be praying for a speedy and complete recovery. I would be obliged if you would as well.

Cone Photoreceptor Transplantation in Mice
Researchers in the U.K. conducted a proof-of-concept study that restored some degree of vision in mouse eyes transplanted with cone photoreceptors derived from human embryonic stem cells. Previous studies have transplanted stem cells that replaced the retina's pigmented epithelium, or converted mouse skin cells directly into rod photoreceptors. The present work is the first study to transplant retinal cells using using cone photoreceptors, which the authors emphasized for their importance in central and color vision. The researchers developed to variants of human cones: a normal type derived from human embryonic stem cells and a control derived from the peripheral blood of a 40-year-old person with achromatopsia. The functional cone photoreceptors were injected into the retinas of 32 mouse eyes, and the aberrant cones were injected into the retinas of 23 mouse eyes. As an additional study design quality measure, the mice were bred to have advanced eye disease with complete nonfunctional cones to control for the possibility of residual function from existing cones, rather than the transplanted cones. Both types of cones attached to the mice's retinas. Testing with microelectroretinogram, however, showed that only the functional human cones responded to light. Furthermore, only the mice that received functional cones exhibited behavioral responses to light, such as retreating to a dark room in the presence of light, a natural response for these nocturnal animals. The researchers next plan to improve the manufacturing capacity of cone photoreceptors, and they hope to start clinical trials several years in the future.

Digital Eye Strain During a Pandemic
This article in the Washington Post  reports on recent worrisome trends of eye strain and eye damage due to increased computer screen time during the COVID-19 pandemic. The effect is most prevalent in young children, who are susceptible to developing progressive myopia that puts them at increased risk of sight-threatening conditions such as retinal tears and macular degeneration later in life. In addition to extensive near work in a virtual learning environment, aspects such as viewing angle and screen glare/reflections force our eyes to work harder than they usually do when reading a printed page, a professor of neural science and psychology at NYU explains. Computer vision syndrome, also known as digital eye strain, is another contributor to vision problems, including blurred vision and dry eyes. Digital eye strain was also reported to have increased around the globe during the COVID-19 pandemic. The good news is that people can take steps to protect and heal their eyes. Taking frequent breaks from screen use, such as using the 20-20-20 rule of looking at least 20 feet in the distance for 20 seconds every 20 minutes spent on the screen, helps to mitigate eye strain. While taking into consideration precautions of distancing during the ongoing pandemic, the "bright and full-spectral light, rich spatial patterns across a wide range of scales, and sharp images of distant objects" of outdoor environments can help to reduce young children's risk of developing myopia.

Infratemporal Cortex Calibrates for Contrast in the Perception of Novel Visual Information
Visual information starts with the detection of incoming light at the retina's photoreceptors. The complex process is simplified here as then being relayed via the optic nerve to the visual cortex. The present research investigated the role of the intratemporal (IT) cortex in interpreting the complex patterns of visual information, specifically teasing apart the difference between the perception of novel and familiar patterns. According to an earlier theory known as repetition suppression, greater activation of the IT cortex meant that a person was viewing something new, while less activity in the IT cortex indicated familiarity. The researchers, however, note that different images produce different amounts of activity even when they are all novel, possibly influenced by factors such as brightness, contrast, and even memory. They instead propose a new theory called sensory reference suppression that suggests that the brain calibrates for the level of activation expected, correcting for these other factors and leaving behind the signal of familiarity. In particular, to explore the difference between memory and contrast, the researchers presented sequences of grayscale images to two adult rhesus monkeys and recorded the neural activity of their IT cortex, using a unique method that measures the spikes of hundreds of individual neurons. Using mathematical analysis, they found that both familiarity and contrast change the overall firing rate of neurons, and that the brain can tease apart one from the other. The researchers state that understanding how the brain builds memory in the presence of changes in sensory input could have implications for artificial intelligence and memory-impairing disorders such as Alzheimer's.

Naturalistic Driving Among Older Drivers Helps to Eliminate Bias in Traffic Accident Reports
Researchers using data from the Alabama VIP Older Driver Study found that naturalistic driving research confirmed that contrast sensitivity impairment, slowed visual processing speed and deficits in motion perception elevated crash and near-crash risk in older drivers. The study involved a great deal of cooperation from older driver participants, who had devices consisting of five-channel video, accelerometers, and GPS installed on their vehicles with continual recording over a six-month period. As the lead researcher explains, use of in-vehicle instrumentation eliminates biases and incomplete reports due to different perspectives from the drivers, witnesses, and law enforcement. She comments, “Witnesses can have different perspectives, meaning the driver may not feel they were responsible, but other witnesses may disagree. The police officer then has to piece it together and make notations on the accident report as to what they think happened, including whether a driver is at fault. Police officers can also have their own biases. Some may not want to blame an older adult driver, whereas others may hold older adults largely responsible due to stereotyping.” What is especially informative about naturalistic driving research is that it can identify near-crashes. Characterized by the "last-second" evasive maneuver by the driver, near crashes occur more frequently than actual crashes but have similar underlying causes. Furthermore, the study found associations between actual crashes and at-fault and the driver's visual capabilities. Naturalistic driving research can thus aid to provide more objective information for traffic accident reports as well as link at-fault crashes and near crashes with older drivers' vision impairment.

In Other News
(1) A new way of looking at concussions
(2) Christmas tree cataract
(3) Face masks and eye irritation