West Links Environmental Change to Eye Health Hazards
Another reason to worry about climate change: Expanding areas of arid land, air pollution and greater exposure to ultraviolet (UV) radiation all present potential health hazards to your eyes, according to Dr. Sheila West, vice chair for research at the Wilmer Eye Institute, Johns Hopkins University. She recently discussed these hazards at a symposium on the health consequences of climate change.
The tissues at the front of the eye—the cornea, eyelid, the white part called the sclera and even the lens—are all exposed to the environment. Adverse environmental changes may therefore have deleterious effects on the eye, West said at the symposium, sponsored by the NIH global health interest group.
Regions of arid land are expanding as rising temperatures and shifting atmospheric circulation patterns force dry air into regions that had previously seen more rain. Drier air means that more people may be likely to suffer from dry eye symptoms, in which tears aren’t produced properly or evaporate too quickly.
While there’s no evidence that drier conditions cause dry eye, “it can accelerate symptoms in people who are prone to dry eye. As we see these areas [of drought] spread, we are liable to see people who are prone to dry eye, but who may not be symptomatic, go on to develop symptoms,” West said.
In the U.S., about $3.8 billion is spent annually treating dry eye. Those expenditures are likely to increase as the areas with rising temperatures and increasingly arid conditions expand.
Another consequence of climate change is an increased burden of airborne particles that can irritate the eye. Air pollution has long been linked to respiratory disorders; more recently it’s been shown to play a role in eye disease, West said. Drought conditions, now increasingly seen as a consequence of climate change, can prolong the fire season from naturally occurring fires, which emit irritants into the air. As an example of how these fire emissions affect the eye, West pointed to the use of intentional fires set for crop clearing. “We’re seeing more ocular exposure to irritants in the air in these farmland areas,” she said.
West‘s own research has shown that exposure to wood or charcoal cooking fires—ubiquitous in many developing countries—appears to accelerate the scarring caused by trachoma, the leading infectious cause of blindness worldwide. Trachoma is caused by the bacterium Chlamydia trachomatis, which is spread through direct contact with an infected eye, or to nasal fluids. Recurrent infections over a lifetime lead to scarring inside of the eyelids, which in turn causes the eyelashes to turn inward and brush against the cornea, eventually resulting in damage that impairs vision.
By studying women living in areas of rural Africa where trachoma is endemic, West found that, after adjusting for other factors that may contribute to trachoma scarring, the more time the women spent cooking over wood-burning stoves, the more likely they were to have moderate to severe scarring of the eyelid.
On another front, ozone depletion can lead to higher levels of UV light exposure, which is a known risk factor for cortical cataract. Chronic exposure to the sun’s damaging rays can alter the orderly arrangement of proteins in the lens of the eye or damage lens epithelium, causing the lens to become cloudy.
Efforts such as the Montreal Protocol, an international treaty aimed at phasing out the production of ozone-depleting substances, may help reduce UV levels, “but that may not occur until the middle of the century,” West said. Even with the protocol’s measures, West and her colleagues estimated that by 2050, rising UV exposure will lead to an additional 150,000 to 200,000 cases of cataract—over and above the expected number associated with aging. West estimates that $1.1 billion will be spent on care and surgical treatment of these additional cases.
The good news is that these estimates are based on assumptions of how much UV radiation actually reaches the lens of the eye, a controllable risk factor. Wearing a hat can reduce UV exposure by 30 percent. Sunglasses, even simple plastic lenses that offer full UV protection, can reduce exposure by nearly 100 percent.
To watch a video interview with West go to https://www.youtube.com/watch?v=biCNYpOxPNY.
Focus on Developing World
Workshop Links Vision Scientists to Information, Research Tools
If you’re a scientist at NEI, it is relatively easy to find and peruse research papers by others in your field. A PubMed search typically leaves you just one or two mouse-clicks away from the full-text paper(s) you’re seeking. In part, that’s because NIH holds subscriptions to a slew of scientific journals, as do most U.S. research institutions.
Now imagine (or perhaps recall) doing an online literature search from a lab or clinic in southern India, rural China or any other developing part of the world. You’re more likely to hit an “Access Denied” page, because poorer research institutions have limited means to pay for journal subscriptions.
NEI and the NIH global health interest group recently hosted a workshop to address this and other issues faced by vision researchers in the developing world. It was a chance for librarians at vision research institutions in unique parts of the world to share challenges and solutions for improving access to scientific publications and other resources. In developing areas, there’s an urgent need for improvement. Cataract and other treatable eye conditions are still leading causes of blindness in the developing world.
In India, the urgent need for eye health research and education contrasts sharply with low access to information resources. With prices that have climbed 145 percent overall during the past 6 years, online journal subscriptions are becoming increasingly difficult to afford, said Thandavarayan Kumaragurupari, a senior librarian at Aravind Eye Hospital and Dr. G. Venkataswamy Eye Research Institute in Madurai. “When Indian research is published in expensive journals, all too often it goes unnoticed by other researchers in India,” she said.
Sabera Banu, a librarian at LV Prasad Eye Institute in Hyderabad, India, noted that a powerful, global movement toward open-access publishing has “allowed for wider dissemination of work to developing countries.” But open-access journals tend to cover their publication costs by charging authors rather than readers, which can make it challenging for researchers to get their work into journals at all. And some of the most prestigious journals “still require expensive subscriptions,” she said.
A project by the Association of Visual Science Librarians (AVSL) and the Seva Foundation (a U.S.-based charity partnered with Aravind) is working to improve access to journals and information tools for researchers in India and other countries.
Eight eye care institutions in five countries—Aravind and two other centers in India, plus centers in China, Egypt, Nepal and South Africa—will work together to enhance training, resources and collaboration among their vision librarians. The project, called Solution in Sight, was funded by a $140,000 grant from the Elsevier Foundation, a charitable arm of the Elsevier publishing company. AVSL has played a continuing role, “working with medical and research centers to identify their needs, and to provide mini-grants for staff training, Internet servers and books,” said Pamela Sieving, a volunteer with NEI’s international programs. She and all of the librarians invited to speak at the workshop are members of AVSL.
Librarian Qing Liu noted that her library at Tianjin Eye Hospital and Medical University in China has a continuing medical education program to train early-career researchers in literature search and evaluation skills. It’s important for researchers to appreciate that a “library is not just a place, but a service,” she said.
Sieving said she hoped that the workshop would help call attention to opportunities for global collaboration among librarians and among researchers working in the vision sciences. Kumaragurupari offered a case in point. Fungal keratitis (inflammation) in the cornea is a leading cause of vision loss in tropical regions and a major focus of research at Aravind. Though it’s less common in the U.S., there are occasional outbreaks, typically from fungal contamination in contact lens solution. In 2009, researchers at Aravind and the University of San Francisco, California, began collaborating on an NEI-funded trial in India that is helping to develop and test better treatments.