A Simple Guide to Understanding Lens Coatings

After deciding which frame and type of lenses (single vision/bifocal/progressives) you are going for, you have the option of choosing if a coating is right for you. Lens coatings not only provide an extra protection to your lenses but they also improve the appearance of your glasses as well as the quality of the images you see. How many times have you had to remove your glasses when taking photographs because of the flash reflecting on the lens? Or your lenses ended up with scratches despite cleaning them as advised? There are several coatings available and here is how you can know which one can work best for you depending on your needs and lifestyle.

Anti-Reflective Coating

Anti-reflective coating (also called AR coating or anti-glare coating) is a thin coating that eliminates reflections and glare from the front and back surfaces of your lenses. This type of coating also decreases halos around light and creates a nicer cosmetic appearance, making your lenses look nearly invisible. AR coating improves light transmission through the lens for night driving and helps photochromic lenses (see below) reduce glare in bright sunlight. AR coating is highly recommended for all eyeglass lenses, especially for polycarbonate, high-index and aspheric lenses – all of which reflect more light than regular lenses.

Scratch-Resistant Coating

Scratched lenses are distracting and can affect your ability to see clearly. Today, many eyeglass lenses come with built-in scratch resistant coatings, including high-index lenses and lenses made of polycarbonate and Trivex. These types of lenses are treated on the front and back surface with a clear, scratch-resistant coating and have a much harder surface. Kids’ lenses benefit from a scratch-resistant hard coating for greater durability.

UV Coating

Most of us know that cumulative exposure to ultraviolet (UV) radiation is bad for our eyes and is associated with age-related eye problems such a cataracts and macular degeneration. UV light consists of 3 categories: UV-C which is trapped by the ozone of the atmosphere, and UV-B and UV-A which reach the surface of the earth and are present all year round. Lenses that block 100% of both UV-A and UV-B help to ward off the damaging effects of UV radiation. Fortunately, nearly all high-index plastic lenses and most sunglasses have 100 percent UV protection built-in. However, if you choose CR39 plastic lenses, be aware that these lenses require the additional coating applied to achieve full UV protection.

Photochromic Treatment

Photochromic lenses darken automatically in response to sunlight and return to clear (or nearly clear) when indoors. Photochromic lenses are available in virtually all lens materials and designs and can work for people who cannot afford a separate pair of prescription sunglasses or who have light sensitivity. The molecules responsible for the darkening of the lenses require activation via UV radiation, so whether is it a sunny or overcast day photochromic lenses will darken but to different extents. They work similar to a UV coated lens but with the added benefit of being self-tinting. It is recommended to have an anti-reflective coating added to the photochromic lenses for best visual performance.