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LENS COATINGS

Coatings can enhance the durability, appearance and performance of lenses. At Harpenden Eye Centre, coatings come as standard on all of our lenses. Coatings are unnoticeable and will not alter the cosmetic appearance of your lenses. 


Our single vision lenses come with a high quality anti-reflective, scratch-resistant and water-repellent coating. 


Our varifocal lenses come with a premium coating which provides all of the above benefits, along with a grease-repellent and anti-static coating. 


In addition to these coatings, there are several optional extras for the wearer to consider. 


A UV filter offers all the same benefits as the premium coating above, though provides 100% UV protection on the front and back surface of the lens, filtering harmful UV light from the front and neutralising reflected UV light on the back of the lens. 


A specialised blue filter coating also has all the same benefits as the premium coating above, though has been designed to help aid vision in a modern world. A blue filter coating neutralises the blue light emitted from digital screens, reducing eye fatigue, eye strain and sleeplessness. Further benefits also include enhanced contrast and a significant reduction of glare from digital screens.

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LENS MATERIALS - REFRACTIVE INDICES

In  the early days of vision correction, spectacle lenses were made of glass. Glass lenses provide exceptionally clear optics though are heavy and can break easily, potentially causing serious injury to the eye. For these reasons, glass lenses are now rarely used and plastic has taken its place. 


Plastic lenses are made in 5 different levels of refractive index, which bend the light to correct the wearer's refractive error (prescription). The higher the refractive index, the lighter and thinner the lens becomes. Above are the 5 levels of refractive index lenses that are available. All the lenses displayed contain the same prescription, but demonstrate how much thinner the lens can become by increasing the refractive index. Increasing the refractive index can cause the lenses to become up to 50% thinner and lighter in some cases. Our dispensers will recommend which refractive index will be most beneficial to you with your prescription.  Our dispensers can also recommend ways in which to hide the thickness of your lenses, such as using a thick-rimmed plastic frame, or opting for a narrower frame if you are very short-sighted in order to minimise the edge thickness of your lenses.