Whats the difference?
Not every pair of sunglasses is equal. Despite what many people believe, the darkness of a lens has absolutely no effect on its overall UV protection. Many aspects contribute – from the material of a lens, the shape of the frame, the colour and other coatings, particularly anti-reflective coatings. Here’s how:
Materials used to make lenses (corrective or sunglasses) have different levels of UV absorbers and thus offer varying levels of UV protection. Some, like polycarbonate, are also more resistant to shocks and thus more adapted to certain sports and outdoor activities.
The shape of a frame, eg wraparound sunglasses, may cover more of the eye and sensitive area around the eye to block out light from the sides and reduce UV rays passing between the frame and your face.
Sun lenses are ranked according to the darkness of their tint in categories from 0 (light tint) to 4 (darkest). Lower ratings are more adapted to weak sunlight; category 4 is designed for extreme sun conditions.
Tints can be a fixed color across the lens, have a gradient color that’s darker at top than bottom, or even adapt to be darker when its brighter (photochromic).
While many people choose sunglass colors for aesthetic reasons, different lens colors can enhance perception in different environments and for different activities.
Which is your ideal solution
How to check if your sun lenses are polarized?
To check if your sun lenses are polarized, hold the sunglasses in front of a computer screen, rotate them 90°. The screen should go dark through the lenses. If the lenses are not polarized, there will be no change.
Corrective lenses with a variable tint are known as photochromic: they adapt their shading to different levels of sunlight and UV. In bright conditions, the lens will darken and in less intense sun it will become lighter while remaining tinted. Some photochromic lenses are also polarized for ultimate visual comfort.
Other coatings that can be added to sun lenses include:
Mirror – can also increase protection against UV, infrared and HEV light and is recommended for sports activities in extreme sunlight such as skiing and water sports.
Anti-reflective (AR) – to provide additional UV protection on both sides of the lens, as well as resist water, grease, dirt and scratches for better transparency and clarity.
The higher the E-SPF® Index, the greater the level of UV protection
The E-SPF® index was developed by Essilor in 2012 and endorsed by third party experts to guide consumers on the level of UV protection of a lens. The E-SPF® index measures the UV protection provided by both sides of the lens and ranges from 10 to 50+: the higher the E-SPF® index, the greater the level of UV protection provided by the lens. E-SPF® rating system is used for sun lenses as well as clear lenses.