Lens Thickness/ Lens Index

a.    Standard Spheric 1.50 Lens Standard index 1.50 lenses are spheric lenses, they come an with anti-scratch hard coating and 85-90% UV protection coating (Please choose higher index lenses to get 100% UV protection), and are shatter-resistant, suitable for spherical power +/-1.00 or below, and cylindrical power +/-1.00 or below. b.    Super Flex Aspheric 1.56 lens Super flex 1.56 lenses are super light and highly impact-resistant with a 100% UV protection coating. These lenses are recommended for rimless and sports eyeglasses. The lenses are suitable for a spherical power of +2.00~+4.00/-2.00~-3.00 or below with cylindrical power +/-2.00 or below. c.   Thin Spheric  1.56 lens Thin Spheric (1.56) lenses come with an anti-scratch hard coating and 85-90% UV protection coating (Please choose higher index lenses to get 100% UV protection). The higher index lens greatly reduces the thickness of the lens edge, and they are suitable for spherical power of +2.00~+4.00/-2.00~-3.00 or below, and cylindrical power of +/-2.00 or below. d.   Super Flex Aspheric  1.60 lens Super flex 1.60 lenses are super light and highly impact-resistant with an anti-scratch hard coating and 100% UV protection coating. These lenses are recommended for rimless and sports eyeglasses. High index is suitable for spherical power of +4.00~+6.00/-3.00~-6.00 or below with cylindrical power +/-2.00 or to +/-3.00. e.   Advanced-Thin Aspheric 1.60 lens Advanced-Thin Aspheric (1.60) lenses are high index lenses with an anti-scratch hard coating and 100% UV protection coating which are suitable for wearers with spherical power from +4.00~+6.00/-3.00~-6.00, and with cylindrical power from +/-2.00 to +/-3.00. f.    Super Thin 1.67  Aspheric  lens Super Thin Aspheric (1.67) lenses are light, thin and scratch-resistant with 100% UV protection coating. Also, they are more impact-resistant than CR-39 resin lenses. They provide optical performance similar to glass lenses, as MR-7 lenses have a high index and Abbe number. The lenses are suitable for strong prescription, with spherical power from +/-6.00~+/-9.00 and cylindrical power from +/-3.00 to +/- 4.00. g.   Ultra Thin 1.74 Aspheric Lens Ultra Thin Aspheric(1.74) lenses come with a 100% UV protection coating and they are suitable for strong prescription, with spherical power from +/-9.00~+/-22.00 and cylindrical power from +/-3.00 to +/- 4.50.   A specific example is shown below on the indexing of a -4.00-lens prescription on how thin the lens could be.<img alt="" src="https://df5apg8r0m634.cloudfront.net/images/2018/0228/U18vB0MMZD.jpg" /> Each lens type is made from different materials. The higher index materials allow for flatter curved lenses and are still able to maintain an aspheric design. Both of these features help produce thinner and lighter lenses. Please Note: 1. The ultimate thickness of the lenses is determined by the frame size (including lens height, lens width), frame material and your PD. If you choose a big frame the lens edge will need to be as thick as the frame. Frames with thin metal rim will also make the lens look thicker. If the frame is not the best for your PD, the lens may not fit as well or be as aesthetically pleasing as you could have otherwise had.   2. It is important to choose suitable lens index according to your prescription, as this will not only impact aesthetics/thickness of lens, but also the comfort of the glasses and lens. When you fill in your prescription, our website will recommend the suitable lens index for you automatically. If you are not sure if this is correct or need assistance then ,simply email your original prescription to service@firmoo.co.uk. Our Customer Services Representative will contact you to discuss the best lenses for you.