How to choose lens coating for your glasses

The next time you're at the opticians searching for glasses, stop and think. Lens coating can improve the operation and look of opthalamic lenses. It can make them look better, it can make you see better, it can give you protection.

If you ARE thinking of lens coating for your next pair of spectacles, spare a moment to consider a few things.The coating the prescription lenses have will vary the quality and price of your glasses considerable.

Scratch resistant lens coating.

No spectacle-lens substance is absolutely scratch proof. However, a plastic ophthalmic lens that is processed with a hard coating does become more resistant to scratching such as from minor falls or the occasional cleaning with a kitchen towel.

Low viscisity lens coating solution

A low viscosity lens-coating solution is applied on ophthalmic lenses made from plastic materials and cured to form a scratch resistant coating solution.

The lens coating is an easy process and can be used with typical dip and spin coating apparatus and air circulating ovens. Treatment with this results in a veneer of homogeneous depth (2-4 microns) on the lens. Lens coating is generally resistant to commonly used eyewear cleansers.

Children’s lenses in particular profit from a scratch resistant hard coating. The everyday bumps and scratches that children subject them to, would quickly damage untreated lenses. Since scratch resistant lenses are discretionary, make sure your optician knows you want them.

Given that a resistant coating can’t wholly shield your lenses from abrasion, do keep your glasses in a proper case, and clean them with a recommended cloth and cleaning solution

To enhance both the ability to see through the lens and the look of the glasses, an anti-reflective coating (AR coating) is useful.

AR coatings are analogous to the coatings found on camera lenses. They are made up of a number of layers of metal oxides applied to both sides of the lens surfaces.

Because of this layering, AR coatings sometime have a suggestion of green or purple colour, depending on the manufacturers prescription.

A further lens treatment that is valuable but invisible to the eye is ultraviolet (UV) protection. Just as we use sunscreen to keep the sun's UV rays from harming our skin, UV cure in lenses prevents those rays from being detrimental to our eyes. Exposure to ultraviolet light is considered a cause of cataracts, retinal impairment and other eye trouble.

Ultraviolet treatment is straightforward and fast to put on to most plastic lenses, and does not modify the look of the lenses. The exclusion is polycarbonate lenses, which don't need anti-UV treatment because it is an inherent property of the material.

To draw a distinction there are also anti-reflective coatings, which are quite clear, but offer no eye protection. Mirror coatings are simply an audacious statement. As the name suggests, the coating is very reflective.

Options comprise many colours including silver, gold and copper mirror coatings.

Mirror coatings are solely decorative: the wearer notices no change in ability to see no matter what colour the coating is. Only those looking at the person with the glasses will see the colour of the coating. Mirror coatings are commonly used in conjunction with sunglass lenses.

So, you pays your money, you takes your pick. Think carefully, choose wisely. Don't waste your money on something you might not want. Spend your money where it's most needed.