Polarised sunglasses effectively protect your eyesight by reflecting glare. They are invaluable in a number of situations, particularly in many outdoor activities, such as driving, boating and fishing. Polarised lens work by filtering the flare that results from light shining on certain surfaces, such as water. They reduce the sun's harmful UV rays, thereby guarding against damage to retinas. Testing sunglasses for polarisation is a simple yet important step when buying new eyewear.
Hold the pair of sunglasses being tested up to the light. It doesn't matter what the light source is -- it can be indoor or outdoor light.
Place a pair of polarised sunglasses in front of the pair that is being tested so that one lens from each pair is overlapping. Look through both lenses.
Rotate slowly one of the pairs of sunglasses until it is at a 90-degree angle relative to the other pair. Look carefully through the lenses as you do this. If both pairs of sunglasses are polarised, the light will be blocked when you look through the overlapping lenses.
Don't let a higher price deter you from buying a pair of polarised sunglasses. Polarised sunglasses are an effective way to protect your eyesight and are essential if you spend a lot of time outdoors.