Following a long and cold winter, we are finally embracing the joy of the much-awaited spring season and sunny days. During these days when we bask in the sun, I wanted to take a closer look at the effects of UV rays on our eye health.

While most people are aware of the negative effects of UV rays on the skin, unfortunately, the impact of UV rays on our eye health is not as widely known. However, just as our skin is exposed to UV rays, our eyes are exposed to the same, if not more, UV rays.

Similarly, while many people take care to use sunscreen to protect their skin from UV rays, they may not know how to properly and effectively protect their eyes from UV rays.

The ozone layer surrounding our planet largely filters out UV rays that reach the Earth’s surface. However, in recent years, the thinning and deterioration of the ozone layer have made it necessary for us to be more conscious and sensitive about protecting ourselves from UV rays for the sake of our health.

What are the UV rays emitted by the sun, and how do they harm tissues?

The sun is the natural source of UV energy. It’s important to understand that UV is not visible light but rather a form of radiation. When UV rays are absorbed by living tissues, they release energy that can cause various forms of damage at the cellular level. The shorter the wavelength of UV rays, the more intense the energy they release and the more severe the damage they can cause to tissues. For example, UVB rays with shorter wavelengths cause much more damage to the eyes than UVA rays. On the other hand, longer-wavelength UV rays penetrate deeper into tissues. While the harmful effects of UVB are more pronounced on the surface of the eye, especially on the cornea, the harmful effects of UVA are more pronounced in the deeper tissues of the eye, such as the intraocular lens and the retina.

UV rays demonstrate their harmful effects at the cellular level by damaging the DNA structure. The energy they release breaks the hydrogen bonds in the DNA chain. As a result, protein synthesis is affected, and the vital functions of the cell are disrupted. This can lead to cell death or uncontrolled growth, potentially resulting in cancer cells.

What are the effects of UV rays on our eyes?

The tissues that absorb the most UV rays in the eyes are the cornea and the intraocular lens. UV rays can cause chronic damage to many tissues, and diseases such as cancer may take years to develop. However, the discomfort caused by photokeratitis, a condition resulting from UV exposure to the cornea, also known as snow blindness, can occur rapidly. Within hours of exposure, it can cause severe pain, watering of the eyes, eyelid spasms, and sensitivity to light. A person may feel so much pain that they cannot keep their eyes open. It’s important to note that the primary culprits behind photokeratitis are not the UV rays that come directly from the sun to our eyes but, rather, UV rays reflected from the surrounding environment. While snow reflects 80-94% of the UV rays that fall on it, water reflects only 5-8%. Exposing your eyes to UV rays reflected from snow for just 1 hour without protection or to UV rays reflected from sand or water for 6-8 hours without protection is sufficient to cause photokeratitis in the cornea. In cases with shorter exposure times, individuals may experience mild to moderate discomfort, stinging, tearing, and burning in the eyes.

Long-term exposure to UV rays can lead to eye diseases that develop over time. Some of these include the yellowing and formation of cataracts in the transparent intraocular lens, the formation of unwanted tissue caused by cellular damage in the conjunctiva, the development of cancers such as carcinoma or melanoma on or around the eyes or eyelids, and an earlier onset of age-related macular degeneration, a disease of the retina at the back of the eye that leads to vision loss. Effective protection from UV rays can reduce the risk of developing these eye conditions. For example, scientific studies have shown that wearing sunglasses continuously can reduce the risk of developing posterior subcapsular cataracts, believed to be caused by oxidative damage from light, by up to 40%.

When should we start protecting our eyes from UV rays?

We must begin protecting our eye health from UV rays at an early age. Children have smaller eye globes, relatively larger pupils, and more transparent intraocular lenses compared to adults. This means that even if children are exposed to UV rays for the same amount of time as adults, their eye tissues absorb a greater amount of UV radiation. After the age of 25, only about 10% of UV rays that reach the eyes penetrate to the retina at the back. In contrast, in children, this percentage is about 75%. According to research by the World Health Organization, our eye tissues are exposed to about 80% of the UV radiation they will encounter in a lifetime before the age of 18. Therefore, starting protection from UV rays during childhood can reduce the risk of developing certain eye diseases, such as cataracts, later in life. In addition to sunglasses, it is advisable for young children to use hats with protective fronts when they go out in the sun.

During which hours of the day are our eye tissues more exposed to UV rays?

Knowing the hours during which our eyes are more exposed to UV rays is essential for taking effective precautions. It is well known that the hours when our skin is most affected by UV rays are from 10 AM to 2 PM when the sun is directly overhead. However, the situation is quite the opposite for our eyes. In a study conducted in Japan to determine the hours during which eye tissues are most exposed to UV rays, researchers measured the UV rays absorbed by eye tissues at different times of the day. As a result, it was shown that the hours when eye tissues are most exposed to UV rays are early in the morning (between 8:00 AM and 10:00 AM) and late in the afternoon (between 2:00 PM and 4:00 PM) when the sun is relatively bright but not directly overhead. In light of this new information, we can say that even during hours when the brightness of the sun does not bother our eyes, we should not neglect to use sunglasses, as these are actually the times when we need to protect our eyes the most.

When choosing sunglasses:

• Pay attention to the frame fitting well on your eyes to block reflected UV rays effectively.
• Ensure that the lenses filter out UVB and UVA rays by 99-100%.
• Opt for sunglasses with lighter-colored lenses rather than dark ones whenever possible. Lighter-colored lenses help keep the pupils small and reduce the amount of UV reaching the back of the eye.

Does using poor-quality sunglasses with tinted lenses that do not filter UV rays harm our eyes?

Absolutely, it does. Our eyes have natural defense mechanisms to protect against UV rays. When the intensity of light increases, our eyelids reflexively narrow, and our pupils immediately shrink. This reduces the amount of UV rays reaching our eye tissues. Sunglasses with darkly tinted lenses reduce the amount of light reaching the eye, creating a perception of darkness. In such cases, our eyelids do not narrow, and our pupils widen. As a result, the amount of light reaching the eye is reduced, but unfortunately, UV is not visible light and continues to reach the eye surface. Moreover, our natural defense mechanisms are disabled, causing an increase in the amount of UV rays reaching the intraocular tissues.

In conclusion, a person who uses poor-quality sunglasses with lenses that do not filter UV rays is exposed to a higher amount of harmful UV radiation in eye tissues, especially the intraocular lens and retina, compared to someone who does not use any sunglasses.

Do contact lenses provide protection against UV rays?

There are contact lenses available that meet the standards set by the FDA and ISO for filtering UVA and UVB rays. Contact lenses in Class I block at least 90% of UVA rays and 99% of UVB rays. Class II contact lenses block at least 70% of UVA rays and at least 95% of UVB rays.

Contact lenses made from a special material called senofilcon A, which is considered Class I, provide the most effective UV protection.

Many silicone hydrogel lenses, which are widely used, can also provide Class II UV protection. Colored contact lenses used for cosmetic purposes that block UV rays are also available.

Is wearing contact lenses alone sufficient protection from UV rays?

Since contact lenses that filter out UVA and UVB rays can block almost 100% of the reflected rays from the environment, they are more effective than sunglasses in protecting the cornea, intraocular lens, and retina. However, even when using contact lenses, it’s essential to remember that areas of the eye not covered by the lenses, such as the eyelids and the conjunctiva, need additional protection from UV rays. Therefore, in addition to contact lenses, sunglasses or hats with protective fronts should be used to protect these areas.

How can we effectively protect our eyes from UV rays?

We must start protecting our eye health from UV rays at a young age. It’s important to remember that sunglasses alone are not enough for UV protection, especially during the hours when our eyes are most exposed to UV rays, which are early in the morning (8:00 AM – 10:00 AM) and late in the afternoon (2:00 PM – 4:00 PM). During these times, it is necessary to use sunglasses along with hats that have protective fronts for effective protection. Additionally, for those who use contact lenses, especially children, it is advisable to choose Class II lenses that filter both UVA and UVB rays. Cosmetic colored lenses that block UV rays can also be a good choice. However, even when using contact lenses, it’s crucial to remember that areas of the eye not covered by the lenses should be protected with sunglasses or hats.