Climate change and eye health
The Earth’s changing climate can affect human health. This includes eye health since the eyes are constantly exposed to the outside environment. Embracing sustainability can help reduce some of these environmental impacts, lessening the negative effects on human health over time.
Greenhouse gas emissions have contributed to rising temperatures. This has caused further changes to the environment, like more extreme weather. As the climate changes, it’s becoming more important to understand how it affects the human body. This is especially true for the eye, which is in constant contact with the outside environment.
While its effects on the weather are important, it’s also important to consider the indirect effects of climate change. These can include:
- How diseases spread through air, water and food
- How we grow and transport food, which could result in scarcity and nutritional deficiencies
How heat and sun exposure affect your eyes
There are two primary ways the sun can cause damage to your eyes:
- Photochemical – Photochemical damage is caused by reactive oxygen species (ROS), which can damage cells. When there are too many ROS in the eye, antioxidants can’t protect against their effects. This causes a state called oxidative stress.
- Thermal – Thermal damage happens when heat causes proteins to change their shape.
UV damage
Sunlight contains ultraviolet (UV) light. UV light is a type of radiation that can damage the eye, in addition to other body parts. The ozone layer absorbs some of the UV light coming from the sun, but it’s becoming thinner over time due to climate change. This means more UV radiation is able to make its way through.
The effects of UV damage depend on the wavelength of the light. Shorter wavelengths are typically absorbed by the cornea, but longer ones can reach the lens or even the retina. This leads to damage through oxidative stress.
The effects, especially after years of exposure to the sun, can include:
- Cataracts – Cloudiness that forms when proteins in the lens (the part of the eye behind the pupil that focuses light) break down.
- Pterygium – A growth that spreads from the conjunctiva (the clear membrane that covers the white surface of the eye) to the cornea (the front area of the eye shaped like a dome in front of the colored part of the eye).
- Age-related macular degeneration – When the center of the retina (the layer of tissue at the back of your eye that senses light) is damaged.
- Photokeratitis – Damage caused to the eye from exposure to UV rays. It can be either acute (starts suddenly and doesn’t last very long) or chronic (long-lasting from greater exposure).
The effects of UV damage depend on the wavelength of the light. Shorter wavelengths are typically absorbed by the cornea, but longer ones can reach the lens or even the retina. This leads to damage through oxidative stress.
READ MORE: 5 eye problems linked to sun damage
Heat-related risks
Climate change can cause higher temperatures over time. Increased carbon dioxide causes more heat to be trapped in the Earth’s atmosphere. The eye needs to stay moist to keep itself healthy and protected. But hotter weather causes more tears to evaporate, which can lead to dry eyes.
Dry eye happens when the layer of tears that protects the eye (the tear film) is disrupted. When the tear film is disrupted, it can’t do its job, leading to more symptoms as the disease progresses.
High temperatures are also associated with other eye conditions, although how they cause them isn’t known for sure yet. It is thought that longer exposure to heat may cause cataracts by affecting the area of the eye around the lens, making it easier for them to form. High temperatures may also be involved in:
- Trachoma – An eye infection caused by a specific bacterium. High temperatures may mean a higher number of flies that carry this disease.
- Retinal degeneration/detachment – Damage to the retina or when the retina separates from its supporting tissues. It’s theorized that high temperatures cause dehydration of the vitreous, the fluid that fills the back of the eye. This dehydration then causes further problems, like changes in pressure or volume that lead to detachment.
It’s not just tropical climates where heat is a concern. Areas within cities can become urban heat islands. This means their temperature is higher than that of surrounding rural or more vegetated areas. Urban heat islands are caused by the radiation of heat from roads and buildings.
Air pollution and eye irritation
Air pollution comes from a mixture of gases and particles in the air at amounts that are high enough to affect human health. Climate change is affecting the kinds of pollutants in the air and how they’re distributed. There are pollutants in the air, both inside and outside. They’re not always completely separate, and both can irritate the eyes.
Outdoor pollutants (like pollen) or indoor pollutants (like cooking smoke or cleaning products) can aggravate eye allergies and cause inflammation in the conjunctiva known as conjunctivitis. Smoke from wildfires can also irritate the conjunctiva.
Air pollution can also cause oxidative stress and inflammation. These may result in damage that leads to glaucoma. Glaucoma is a disorder that results in optic nerve damage from a buildup of pressure in the eye over time.
Wetter weather and higher risk of eye infections
In general, it’s not good for the eyes if either temperature or humidity reaches extreme levels. Climate change may be causing higher humidity over time. High humidity allows pathogens like fungi to live and spread, making it easier to catch infectious diseases.
More flooding as a result of climate change may also be related to a higher outbreak of infectious eye diseases. Flood water can raise exposure to pathogens, especially if there isn’t an adequate drainage system in place. For instance, eye infections from a pathogen called Acanthamoeba were shown to rise after a flood in Iowa.
Food insecurity and vision problems
Climate change can cause droughts and crop failure, leading to less available food. This causes food insecurity, which then leads to malnutrition. A diet that does not include key nutrients can cause vision problems later on.
In communities with food insecurity, malnutrition (especially vitamin A deficiency) can lead to a variety of eye diseases, like degeneration of the retina. Effects can also include:
- Corneal xerosis – When your cornea gets too dry.
- Night blindness – When seeing at night or in the dark becomes too difficult.
Who’s most at risk for climate-related eye issues
Marginalized communities or those that experience inequities are most at risk for the adverse effects of climate change.
For instance, people in low- or middle-income nations are more likely to suffer from food insecurity. People in rural communities or who spend long hours working or playing sports outside are at risk of more exposure to radiation from the sun. They are also at risk of infectious diseases, especially in humid environments. So are people who live in conditions that can contribute to poor hygiene, like hot climates and communities with poor infrastructure.
Children may also be at more risk. The lenses of their eyes are more transparent than in adults, so more radiation can get to the retina.
How sustainability can support eye health
Sustainable practices can help reduce the emissions associated with climate change, eventually lowering the impact on human health, including the eyes and vision.
Recycling and reusing materials are sustainable practices that can be done personally and practiced at a larger scale. Many companies in the health care and eyewear sectors have incorporated sustainability into their business models. For instance, EyeSustain is a coalition of organizations and professionals dedicated to reducing the environmental impact of the optical industry.
Supporting organizations with green initiatives — especially ones that have eco certifications — can have a positive impact on the planet and your eye health.
READ MORE: Sustainable eyecare: Practices every consumer should know
What you can do to protect your eyes
You can’t control larger environmental factors, but there are things you can do to protect your eyes.
Stay protected outdoors
The sun is strongest in the middle of the day and in the afternoon. If you can’t avoid going outside at those times, it’s important to take steps to protect your eyes.
Wearing sunglasses can prevent excessive exposure to UV light. Sunglasses even come with UV-A and UV-B protections, so be sure to check for 100% UV or UV400 protection. Wearing a hat (especially one with a brim) can add an extra layer of protection. If you wear contacts, you can also get contact lenses that absorb UV light.
You can’t control how much pollution is outside, but you can do your best to avoid where it’s worst. Spending time in areas with a lot of vegetation can also help lessen your exposure to pollutants.
Stay protected indoors, too
Replace filters for your heating or cooling systems and use an air purifier. Limit your use of aerosols (like hairsprays or spray deodorant). Like outdoors, plants can also help remove harmful pollutants from the air.
Watch for eye changes and get annual exams
Consider scheduling your annual eye exam to ensure your vision is clear and your eyes are healthy. Your eye doctor can educate you on best practices for UV protection, update your eye prescription and help manage any eye issues related to the environment.
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