“ / Type: Spectacles „
High index spectacle lenses are thinner and lighter than normal spectacle lenses. This makes them ideal for people with higher prescriptions. Quality lenses in high index plastics and glass are available from Nikon, Zeiss, Hoya. Pentax and Rodenstock and various other companies. Some people are very fussy or very self-conscious about how thick their lenses look. For these people, high index lenses are a great way of reducing the thickness and also the weight. For an even thinner lens, aspheric lenses are available. These lenses are slightly flatter than spherical lenses and this makes the lenses look thinner. The downside with aspheric lenses is that some people have trouble with distortions at the periphery, although with the current trendy (small) frames there isn't a lot of periphery to see. High index lenses also tend to come with all kinds of coatings. Normally an anti-reflection, anti-scratch and hydrophobic coating. This means lens scratches less easily, reflects less light (a good thing both cosmetically and technically) and repels water. The hydrophobic coating reduces the ease with which the lenses steam up. As with most things in life, however, this extra "performace" comes at a higher price than ordinary lenses. Prices will vary between manufacturer and your dispensing optician will probably be able to advise you.
I currently wear spectacles fitted with Nikon DXII aspheric lenses in an ultralite weight Police frame (model 2541, bought from D&A). I wore contact lenses for years and decided it was time to start wearing glasses again (they are very fashionable now) but don't like having a lot of weight on my face. I am quite short sighted (a 5 dioptre myope, ask your optician) and therefore need quite powerful lenses. The Nikon DXII lenses are expensive but are extremely good quality. With all the coatings (anti-reflection, anti-scratch, water repellant) they are among the best lenses available. Being aspheric, they are thinner than standard lenses and being high index (that's refractive index) they are thinner than normal lenses. My lenses are the same thickness as a friend who has normal lenses, but whose eyes are five times better than mine. If you wear glasses and want light, thin, quality spectacle lenses and don't care about the cost, then these lenses are worth considering.