Do you wear your contact lenses in the office? Do you have a moderate to high short -sighted prescription? Getting tired eyes from using the computer all day? If you answered yes to all 3 questions there is an explanation!
Did you know your eyes actually work harder when looking at a computer screen with your contact lenses compared to glasses? This is because there is nil distance from the contact lenses to your eyes. The distance from your glasses to your eyes is usually between 12mm to 14mm known as the vertex distance. When you view a near object through your glasses, your glasses induce prism. What is prism? Prism can be thought of as the shifting light in one direction. For example, if you look through a pair of glasses with a high prescription, you may notice that objects may appear shifted to one direction appearing more towards the left/right/top/bottom than it really is. This effect is known as prism and is caused whenever there are differences in thickness in an optical product. Your contact lenses have a minimal difference in thickness between the middle of the lens and the edge and because you’re always looking through the optical centre of the contact lens they don’t induce any prism. Your glasses however induce prism. For people who are short-sighted your glasses actually induce prism in favour to viewing a computer screen or something close. Your eyes actually work less!
This is the opposite for people who are long-sighted. Everything is reversed. Your eyes work harder looking through glasses and less through contact lenses. Often wearing contact lenses with near related tasks can be beneficial with contact lenses. This is because glasses with are for long sighted people induce prism not in favour of viewing a computer screen.
These facts are useful to know because having tired eyes at work is a common problem. Consider wearing your glasses on some days if you have a moderate to high prescription short-sighted prescription. And if your long-sighted, consider wearing contact lenses! See if you can feel the difference.