For eye infections, delayed doctor visits and extent of damage affect vision outcomes
Expert Q&A on causes and treatment of microbial keratitis
Even though microbial keratitis is a preventable cause of blindness, it's a complex infection to treat, and many patients have lasting vision impairment.
Previous studies have identified several risk factors for reduced vision after treatment, including delays in symptom onset, longer duration of symptoms and existing eye disease.
However, these studies were restricted to one geographic area or a single type of organism that causes the infection.
In a study published in Ophthalmology, physicians followed 562 patients in the United States and India over a three-month period to identify risk factors that could be easily managed with early intervention.
Maria A. Woodward, M.D., an associate professor of ophthalmology and visual sciences and a member of the Institute for Healthcare Policy and Innovation, answers questions about what causes microbial keratitis, symptoms and preventative measures.
What are the common causes for microbial keratitis?
Woodward: We are surrounded by microorganisms, including Staphylococcus aureus, Streptococcus and fungi, which can get into our eyes through small injuries.
This is a common outcome in patients who do not have good contact lens hygiene or have an underlying eye condition that makes them prone to infections.
Although we don’t know the prevalence rates in the U.S., worldwide it affects over 2 million people per year.
What are symptoms of microbial keratitis?
Woodward: It depends on the infection. Some types of bacterial infections can progress incredibly quickly while fungal infections are slower.
Early symptoms include eye pain, severe eye redness and blurry vision. Some patients also experience light sensitivity.
Unfortunately, many ignore these warning signs and continue to use contact lenses, which can make the problem worse.
If left untreated, the condition causes eye pain and can ultimately penetrate deeper into the eye resulting in scarring and vision loss.
What factors affect treatment for microbial keratitis?
Woodward: The majority of infections in the U.S. are usually treated with antibiotic eye drops.
In our study, we found that if a patient had reduced vision or waited for symptoms to worsen, treatments did not work as well.
Interestingly, we saw that patients in the U.S. who wore contact lenses had slightly better outcomes.
We suspect that their physicians could easily identify what kind of infections are associated with wearing lenses and were able to treat them earlier.
In India, we observed a similar effect in patients with a history of eye trauma.
In rural areas, it's common for people to get something in their eye that can lead to an infection.
It’s possible that the physicians there knew what kind of infection they might have, given their environment and history, and were able to administer treatments sooner.
What future directions are you excited to pursue?
Woodward: Although this work doesn't represent everyone globally, we found some commonalities regardless of where the participants were from.
It is important to expand these studies to include factors such as access to medications and adherence to eyedrop regimens.
As part of this work, we took serial photographs of patients over time to monitor how their eye characteristics change over time.
We can use this to help physicians distinguish between mild and severe cases and treat patients effectively.
Journal
Ophthalmology
Method of Research
Observational study
Subject of Research
People
Article Title
Factors Associated with Vision Outcomes in Microbial Keratitis – a Multisite Prospective Cohort Study
University of Cincinnati study finds vision loss fear may keep some from having cataract surgery
Research underscores importance of doctor-patient trust, communication when making medical decisions
Fear of vision loss may deter some patients from undergoing necessary cataract surgery, according to a newly published study. Cataracts are the leading cause of reversible blindness, and surgery remains the only effective treatment.
The study, recently published in The Journal of Clinical Ophthalmology, highlights the trust patients place in their physicians and the critical role of doctor-patient communication in making medical decisions.
The research was led by Lisa Kelly, MD, a Taylor Asbury-endowed professor-educator and director of medical student education in the Department of Ophthalmology at the University of Cincinnati College of Medicine. Kelly also serves as medical director of UC eye clinics. The study’s corresponding author was Samantha Hu, a fourth-year medical student. Stephanie Wey, MD, a former UC resident, and Rainier Yono, a third-year medical student, also contributed.
The research team surveyed 42 patients at Hoxworth Eye Clinic, the training site for UC’s ophthalmology residents located near UC Medical Center. The study explored a possible link between health literacy and fear surrounding cataract surgery.
“We hypothesized that patients with lower health literacy would fear surgery more, especially the risk of vision loss,” said Hu. “But our findings didn’t support that.”
Cataracts develop when proteins in the eye’s natural lens break down and clump together, leading to blurry or dimmed vision. Because the condition is most commonly age-related, those surveyed were all 50 and older. Sixty percent reported a yearly income below $50,000.
Study findings
Among those surveyed, 36% reported fear of cataract surgery, and more than half of those specifically feared it would lead to vision loss. However, researchers found no correlation between this fear and a patient’s health literacy level.
“We found patients who would benefit from surgery reasonably understood the procedure after we educated them,” Kelly said. “But even with clear explanations, sometimes their fear persisted.”
Hu noted that simply providing more information wasn’t always helpful. “Overloading patients with data doesn’t necessarily ease their concerns,” she said.
Instead, the study pointed to the importance of open communication.
“Yes, patient education matters, but it’s not always sufficient,” said Kelly. “What’s equally important is building relationships and trust to help patients overcome fear.”
Hu said the findings emphasize how much patients rely on their physicians to guide them to medical decisions based on their individual needs.
“It underscores the trust patients place in their doctors — and the need for physicians to truly understand their patient population,” said Hu.
Kelly added, “It’s a reminder that our patients are people with real fears. Our role is to partner with them in their health care.”
Moving forward, researchers are likely to delve deeper into patients’ fear around cataract surgery and how physicians can further strengthen doctor-patient relationships.
Path to residency
Hu is part of the UC College of Medicine’s Class of 2025. She is originally from Greenwood Village, Colorado, a suburb of Denver.
As Hu became more focused on pursuing the ophthalmology specialty, she said she reached out to Kelly about taking part in research and joined the study in her second year of medical school for the data gathering process.
Hu said she was intrigued by this study because of her interest in the social determinants of health, the economic and social conditions that influence differences in people’s health. “Sam and I spent a lot of one-on-one time together as she worked on this research project,” said Kelly. “I got to know her well.”
The results of the study were first presented at a medical conference last year and likely helped Hu stand out in the competitive residency matching process.
“Engaging with a scholarly question in research like this better positions medical students to take a critical look at the literature,” Kelly said.
After she graduates this spring, Hu will begin her ophthalmology residency at Loyola University Chicago.
Journal
Journal of Clinical Ophthalmology
Method of Research
Survey
Subject of Research
People
Article Title
Fear of Cataract Surgery and Vision Loss: The Effects of Health Literacy and Patient Comprehension at an Academic Hospital-Based Eye Clinic
Scientists trick the eye into seeing new color ‘olo’
UC Berkeley scientists created a new platform called “Oz” that directly controls up to 1,000 photoreceptors in the eye at once, providing new insight into the nature of human sight and vision loss
University of California - Berkeley
image:
UC Berkeley scientists created a new platform called “Oz” that directly controls up to 1,000 photoreceptors in the eye at once, providing new insight into the nature of human sight and vision loss. In this photo, Hannah Doyle, a graduate student at UC Berkeley, operates the Oz system from a laptop.
view moreCredit: UC Berkeley
In Frank Baum’s original novel The Wonderful Wizard of Oz, the Emerald City is said to be such a brilliant shade of green that visitors must wear green-tinted glasses to protect their eyes from “the brightness and glory” of the city.
The glasses are one of the wizard’s many deceits; the city viewed through green-tinted glasses would, of course, only look more green.
But using a new technique called “Oz,” scientists at the University of California, Berkeley, have found a way to manipulate the human eye into seeing a brand-new color — a blue-green color of unparalleled saturation that the research team has named “olo.”
“It was like a profoundly saturated teal … the most saturated natural color was just pale by comparison,” said Austin Roorda, a professor of optometry and vision science at UC Berkeley’s Herbert Wertheim School of Optometry & Vision Science, and one of the creators of Oz.
Oz works by using tiny doses of laser light to individually control up to 1,000 photoreceptors in the eye at one time. Using Oz, the team is able to show people not only a green more stunning than anything in nature, but also other colors, lines, moving dots and images of babies and fish.
The platform could also be used to answer basic questions about human sight and vision loss.
“We chose Oz to be the name because it was like we were going on a journey to the land of Oz to see this brilliant color that we'd never seen before,” said James Carl Fong, a doctoral student in electrical engineering and computer sciences (EECS) at UC Berkeley.
“We’ve created a system that can track, target and stimulate photoreceptor cells with such high precision that we can now answer very basic, but also very thought-provoking, questions about the nature of human color vision,” Fong said. “It gives us a way to study the human retina at a new scale that has never been possible in practice.”
The Oz technique is described in a new study published last week in the journal Science Advances. The work was funded in part by federal grants from the National Institutes of Health and the Air Force Office of Scientific Research.
Untapped photoreceptors
Humans are able to see in color thanks to three different types of photoreceptor “cone” cells embedded in the retina. Each type of cone is sensitive to different wavelengths of light: S cones detect shorter, bluer wavelengths;, M cones detect medium, greenish wavelengths; and L cones detect longer, reddish wavelengths.
However, due to an evolutionary quirk, the light wavelengths that activate the M and L cones are almost entirely overlapping. This means that 85% of the light that activates M cones also activates L cones.
“There's no wavelength in the world that can stimulate only the M cone,” said study senior author Ren Ng, a professor of EECS at UC Berkeley, “I began wondering what it would look like if you could just stimulate all the M cone cells. Would it be like the greenest green you've ever seen?”
To find out, Ng teamed up with Roorda, who had created a technology that used tiny microdoses of laser light to target and activate individual photoreceptors. Roorda calls the technology “a microscope for looking at the retina,” and it is already being used by ophthalmologists to study eye disease.
But for a human to actually perceive a whole new color, Ng and Roorda would need to find a way to activate not just one cone cell, but thousands of them.
A movie screen the size of a fingernail
Fong first started working on the Oz project in 2018 as an undergraduate engineering student, and has created much of the complex software needed to translate images and colors into thousands of tiny laser pulses directed at the human retina.
“I joined after meeting this other student who was working with Ren, who told me that they were shooting lasers into people's eyes to make them see impossible colors,’” Fong said.
For Oz to work, first you need a map of the unique arrangement of the S, M and L cone cells on an individual’s retina. To get these maps, the researchers collaborated with Ramkumar Sabesan and Vimal Prahbhu Pandiyan at the University of Washington, who have developed an optical system that can image the human retina and identify each cone cell.
With an individual’s cone map in hand, the Oz system can be programmed to rapidly scan a laser beam over a small patch of the retina, delivering tiny pulses of energy when the beam reaches a cone that it wants to activate, and otherwise staying off.
The laser beam is just one color — the same hue as a green laser pointer — but by activating a combination of S, M and L cone cells, it can trick the eye into seeing images in full technicolor. Or, by primarily activating the M cone cells, Oz can show people the color olo.
“If you look at your index fingernail at arm's length, that's about the size of the display,” said Roorda. “But if we could, we would have filled the entire visual space like an IMAX.”
The ‘wow’ experience
Hannah Doyle, a doctoral student in EECS and co-lead author of the paper, designed and ran the human experiments with Oz. Five human subjects got the chance to see the color olo, including Roorda and Ng, who were aware of the purpose of the study, but not the specifics of what they would see.
In one experiment, Doyle asked the participants to compare olo to other colors. They described it as blue-green or peacock green, and reported that it was much more saturated than the nearest monochromatic color.
“The most saturated colors you can experience in nature are the monochromatic ones. Light from a green laser pointer is one example,” Roorda said. “When I pinned olo up against other monochromatic light, I really had that ‘wow’ experience.”
Doyle also tried “jittering” the Oz laser, directing it ever-so-slightly off target so the light pulses hit random cones rather than only M cones. The participants immediately stopped seeing olo and started seeing the regular green of the laser.
“I wasn't a subject for this paper, but I've seen olo since, and it's very striking. You know you're looking at something very blue-green,” Doyle said. “When the laser gets jittered, the normal color of the laser almost looks like yellow because the difference is so stark.”
Probing the nature of color vision
Oz isn’t just useful for projecting tiny movies into the eye. The research team is already finding ways to use the technique to study eye disease and vision loss.
“Many diseases that cause visual impairment involve lost cone cells,” Doyle said. “One application that I'm exploring now is to use this cone by cone activation to simulate cone loss in healthy subjects.”
They are also exploring whether Oz could help people with color blindness to see all the colors of the rainbow, or if the technique could be used to allow humans to see in tetrachromatic color, as if they had four sets of cone cells.
It may also help answer more fundamental questions about how the brain makes sense of the complex world around us.
“We found that we can recreate a normal visual experience just by manipulating the cells — not by casting an image, but just by stimulating the photoreceptors. And we found that we can also expand that visual experience, which we did with olo,” Roorda said. “It’s still a mystery whether, if you expand the signals or generate new sensory inputs, will the brain be able to make sense of them and appreciate them? And, you know, I like to believe that it can. I think that the human brain is this really remarkable organ that does a great job of making sense of inputs, existing or even new.”
Additional authors of the study include Congli Wang, Alexandra E. Boehm, Sophie R. Herbeck, Brian P. Schmidt, Pavan Tiruveedhula, John E. Vanston and William S. Tuten of UC Berkeley. This work was supported by a Hellman Fellowship, FHL Vive Center Seed Grant, Air Force Office of Scientific Research grants (FA9550-20-1-0195, FA9550-21-1-0230), National Institutes of Health grant (R01EY023591, R01EY029710, U01EY032055) and a Burroughs Wellcome Fund Career Award at the Scientific Interface.
UC Berkeley scientists created a new platform called “Oz” that directly controls up to 1,000 photoreceptors in the eye at once, providing new insight into the nature of human sight and vision loss. In this photo, Oz creator Austin Roorda, a professor of optometry and vision science at UC Berkeley, demonstrates what it looks like to be part of the Oz experiment.
Credit
UC Berkeley
Journal
Science Advances
Method of Research
Experimental study
Subject of Research
People
Article Title
Novel color via stimulation of individual photoreceptors at population scale
Article Publication Date
18-Apr-2025
