It is well known that excessive sun exposure hurts the skin, but what about the eyes?
UV exposure from the sun has been linked to many different problems within the eyes. It is of utmost importance to do your best to keep your eyes protected from the sun, and this article is here to explain why!
What is UV Light?
UV light is the light energy produced by the sun, tanning beds, electronic screens (TVs, computers, tablets, phones, etc.), fluorescent lights, UV sanitizing devices, and more.
Light in general is part of the electromagnetic spectrum, which measures the wavelength of the light produced by different objects in nanometers (nm).
On the lower end of the spectrum is light energy such as X-rays and UV light. We cannot actually see this light, but we know it exists based off the energy output of these wavelengths.
Toward the middle of the spectrum is “visible light”, or what we as humans can see. This range of light extends from 400 nm (purple/blue colors) to 780 nm (reds).
On the upper end of the spectrum is infrared light and radiowaves, which again cannot be seen but do produce an energy output.
UV light is the category of light that cannot be seen with the naked human eye, and ranges from energy output of 100 to 400 nm.
UV light can be subcategorized into three different categories—UVA, UVB, and UVC.
UVC light is the most dangerous and is produced by the sun. Fortunately, the bulk of this type of UV light is filtered out by the Ozone layer, so it is not regularly absorbed by the human body. UVC light is characterized as any light of a wavelength between 100 to 280 nm.
UVB light is the second most dangerous type of UV light. It is emitted from the sun and can enter the earth and therefore makes contact with the human body. The skin does a fairly good job protecting the body from UVB light, however UVB light can easily pass through the eye if proper safety precautions are not used.
UVB light is characterized as any light of a wavelength between 280 to 315 nm.
UVA light is the least damaging of the UV lights, as it is closest to the visible light spectrum. While it may be safer in comparison to UVB or UVC light, UVA light can still be dangerous, especially when absorbed in excess.
UVA light is characterized as any light of a wavelength between 315 to 400 nm.
Blue light, the light emitted from electronic screens such as computers, tablets, smartphones, and TVs, ranges between the upper UVB to lower UVA range. While research is still ongoing when it comes to blue light, it is considered to be a part of UV light family and precautions should be taken.
Why is UV Light Harmful?
All things are good in moderation—this extends to the sun as well. We need some UV exposure to attain certain vitamins like Vitamin D.
In fact, the body naturally has some mechanisms to protect itself against UV damage—generally speaking the sun is good for us. It’s when we accumulate too much UV exposure overtime, overworking the protective system, that UV light becomes dangerous.
The body naturally breaks down UV light into non-harmful particles in a physiological process called oxidation.
However, when the system has too much exposure to UV light, it can no longer keep up with the oxidative process and harmful particles called free radicals begin to build up in human cells, causing irreversible damage.
A damaged cell here and there may not be problematic, but as more and more cells become damaged and more and more free radicals build up within the body, serious biological changes, like cancer, can occur.
The Eyes’ Natural Defense Against UV Light
The eyes naturally have some protection against the sun. Different parts of the eyes absorb various wavelengths of light to limit what and how much reaches the more delicate, inner parts of the eyes.
However, as more UV light absorbed by these structures, the structures will begin to change and may become damaged themselves.
There are 2 major ocular structures that absorb UV light—the cornea and the lens.
The first structure that comes into contact with UV light is the cornea. The cornea is the clear structure overlying the colored part of your eyes, and is the front most structure of the eye that comes into contact with the outside world.
The cornea absorbs light wavelengths of 280 nm and lower. Essentially, any UVC light that may sneak its way into the atmosphere and possibly some UVB light.
If the cornea is exposed to too much UV light, it can become damaged, resulting in very painful eye inflammation called photokeratitis (essentially a severe sunburn of the eyes) or even growth of excess tissue called a pterygium (an opaque growth that extends from the white part of the eye in toward the center of the eye, possibly obstructing vision, requiring surgery for removal).
The lens is a structure located roughly at the center of the eye. It is a clear flexible structure used primarily to focus images clearly.
The lens works as a safety net, absorbing harmful UV light that may have passed through the cornea with wavelengths up to 400 nm, therefore including protection against UVB and UVA light.
Over time, excessive UV absorption by the lens has been linked to earlier onset cataract development, in which the lens hardens, opacifies, and can obstruct vision.
Why Does this Matter?
When it comes to the eyes—we only get two. While the above problems noted secondary to excessive UV exposure (photokeratitis, pterygiums, and cataracts) can usually be corrected with medical intervention, they do impact activities of daily life.
All of these findings can be irritating and may significantly decrease vision. While photokeratitis typically resolves within 24 hours, it causes debilitating pain. Pterygium surgery has its own risks and its recovery can be quite painful. Cataract surgery is improving daily; however it is also a surgery that comes with its own risks. If you can prevent any of these circumstances from occurring, isn’t it worth it?
Not only that, but if UV light manages to overwhelm the cornea and lens, resulting in transmittance of harmful UV light to the back-most structure of the eye, the retina, it can cause irreversible damage and permanent vision loss through the development of macular degeneration or even melanomas (skin cancer) of the retina.
Therefore, it is of utmost importance to protect the eyes from excess UV light exposure. This is especially true for those for children, as the eyes’ defense mechanisms do not completely mature until around the age of 20 years old.
This means the younger the individual, the more susceptible to ocular UV damage the individual is.
How to Protect the Eyes Against UV Damage
As we well know, UV exposure is unavoidable, and that is okay. What we need to do is make smart decisions to do our best to protect ourselves and our loved ones from excessive sun exposure.
Sunscreen is always recommended when spending time outdoors. Special sunscreen is available for the face and eyelids, which can help to protect the eyelids from excessive UV exposure which may help to prevent eyelid skin cancers from developing.
Sunglasses are also an excellent tool for ocular sun protection. Be sure to look for a “UV Blocking” sticker on sunglasses prior to purchasing them to ensure they contain UV blocking coatings.
This is especially important for those who spend a lot of time outdoors, particularly for those living or working in sand, snow, or water as these terrains all reflect UV light, amplifying how much reaches the eyes.
Wide-brim hats such as floppy sun hats, visors, bucket hats, and ball caps also provide some protection against UV reaching the eyes.
Lastly, one may consider blue light blocking glasses for those who spend extended periods of times on screens. While the research at this time is inconclusive, humans are relying on and using electronics more than ever before, which may prove to have adverse effects a few years down the road.
When it comes to UV damage, prevention is key. UV light is unavoidable, but we can be safe and aim to prevent accumulation of too much UV light to keep our eyes healthy for decades to come.
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