Vision plays an essential role in our daily routines. Our eyes take the light around us and send signals to our brain to create detailed perceptions of the world around us. However, as we grow older, more exposure to the ultraviolet light (UV) rays radiating from the sun can damage our eyes, resulting in blurry vision, light sensitivity, and tearing. How does this happen? To get a better understanding of UV-related eye damage, we first need a sense of how the eye works.

In order to see images, our cornea – a thin and transparent layer on the front of our eye – first bends the light rays, helping us focus our vision. Light then enters our pupil, with the iris controlling how much is allowed to pass through. Next, it travels past our lens and hits our retina on the back of the eye, which then converts the light into electrical signals using photoreceptors. These signals travel to the brain through our optic nerve where they are then converted to the images we perceive. 

National Eye Institute, “How the Eyes Work”, https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work. accessed May 2022.

Over time, the sun's rays can cause damage to the lens, the cornea, and the retina, causing severe eye injuries in some cases. The ultraviolet light that affects our eyes usually does not come directly from the sun. Instead,  UV waves are often reflected, causing them to randomly travel in multiple directions and bounce off surfaces to enter the eye. Externally, our eyelids and eyelashes shield us from some ultraviolet rays and as the light goes through our eye, our internal eye structures also block some light. However, the rays that are reflected are much more prominent in our daily lives and can still cause damage.

One of the most common diagnoses seen in patients is cataracts. Cataracts often affect older adults, when the lens slowly becomes cloudy instead of its natural clear state, resulting in slight blindness or blurred vision until treated. 

A new study has found that ultraviolet B rays directly lead to cataracts through a process called oxidative stress, a normal part of daily function where chemical reactions use oxygen to produce energy and in the process, contribute to aging. The lens is transparent because it lacks many organelles, and instead, consists of mainly water and proteins that allow light to pass through. It is theorized that oxidative stress destroys these proteins, causing them to clump together and block the light from passing. Ultraviolet light damages the lens because it is a substitute for oxygen that prompts oxidative stress through a similar process that includes protein glycation in the lens, a process that changes the composition of the proteins.

To protect our eyes from ultraviolet rays and the possibility of developing cataracts, we should avoid tanning beds and wear hats that shield our eyes from the sun. However, the biggest solution is to continuously wear sunglasses that block UV-A and UV-B rays when outdoors. Sunglasses should not only protect our eyes from unnecessary light entering, but also absorb or reflect the UV rays, which has become common practice with most sunglass manufacturers. Dark grey or green tinted sunglasses also offer more protection from ultraviolet rays. Without sunglasses, we still do have some protection from harmful rays. To reduce the amount of light transmitted through our lens, our pupils constrict and we squint or blink more often, blocking light from entering. This naturally offers us some protection, but wearing sunglasses significantly improves the health of our eyes.

Overall, the sun can cause great damage to our eye health, but injuries are usually preventable with the right precautions.