Ultraviolet rays – What you see and what you don’t

Summer is here, and it feels great. Time to bask in the light of the sun and soak up those rays. But be careful. The sun gives off an enormous amount of energy. According to Dr. David Hathaway, a solar scientist at NASA’s Marshall Space Flight Center that sun shining down on us provides about 1,300 watts per square meter every second to the Earth. The average household light bulb is 60 watts, so the sun is shining the power of 21 light bulbs on one meter of the Earth’s surface every second. Now that’s a lot of energy.

Another word for the sun’s energy is radiation and it comes in different forms. The sunlight we see is one form. The heat we feel from the sun is another. A third form is ultraviolet rays (UV), and while they are invisible to the eye their effects are more than visible to us. Small amounts of UV are beneficial for people and essential in the production of vitamin D. But too much exposure to UV causes sunburn and can affect the health of your eyes and the sharpness of your vision. And while a great deal of media coverage is spent on the risks of skin cancer caused by UV rays, optometrists are worried that people are not as aware of the potential damage UV rays can do to your eyes.


On a bright day your pupils will constrict and your eyes squint to minimise the sun’s light penetrating your eyes. The ridge on your brow, and your eyebrows and eyelashes protect your eyes, but these are of limited use against UV rays. And have you ever noticed yourself squinting even on an overcast day? Don’t be fooled by the weather. On a cloudy day UV radiation exposure may still be high as it can filter through haze or thin cloud.

UV radiation is a risk factor in the development of pterygium (a growth that invades the corner of the eyes), cataracts (clouding of the lens) and macular degeneration (vision loss). Skin cancer around the eyelids is also linked to prolonged exposure to UV rays, as is corneal sunburn, which can be very painful and may even cause temporary vision loss.

Now while these diseases often take many years to develop, it is important to care for your eyes on a daily basis to forestall any risk to your vision.

50% of lifetime exposure to UV happens before the age of 18


You always put SPF sunscreen on your skin to protect against sunburn, but are you doing everything possible to protect your eyes? Help is at hand. The Canadian Ophthalmological Society (COS) recommend the following measures to protect your eyes:

  • Wear UV-blocking sunglasses. Wear them when you’re walking, driving, on the beach, in the water, even when you’re sitting in the shade. For your safety, COS recommends buying sunglasses that block 99-100 per cent of UV light (both UV-A and UV-B).
  • Wear a broad-brimmed hat whenever you’re outside.
  • Never stare directly at the sun. Be aware of UV rays reflecting from sand, pavement, and especially water. The sun’s rays are strongest (and your eyes most exposed to UV rays) from 10am to 4pm.

Children are at a greater risk than adults. Keep children younger than six months of age out of direct sunlight, and ensure children of all ages wear sunglasses and/or broad-brimmed hats when outside. This is very important because the Doctors of Optometry Canada estimate that 50% of lifetime exposure to UV happens before the age of 18.

Lastly, be aware, and get regular check ups at your friendly neighbourhood eye doctor. iSight Optometry has over 60 years experience in surpassing customers expectations. Their highly experienced and friendly staff are here to help you. Early detection, through regular and complete eye exams, is the key to protecting your vision. Be gentle with yourself, and make sure you’re seeing clearly when it comes to the health of your vision. Your eyes will thank you for it.

Contact us for an eye appointment today!