Q. What are your lenses made from? A. High quality, lightweight, CR39 plastic hard ophthalmic resin (1.5 index) lenses - as we are qualified opticians ourselves - we provide you exactly the same high quality lenses as used by your own optician and leading optical chains.     Q. Can I get thinner lenses? A. We can offer lenses, that will reduce the weight and thickness of your lenses. Our optometrist would recommend our thin lenses for prescriptions over +/- 3.00 Dioptres, and very thin for higher prescriptions over+/-4.50 Dioptres.     Q. Do you sell bifocal lenses? A. Yes. They are D28 bifocals - these are standard bifocals most commonly worn. They are set at a height 3mm below the lens centre as calculated by our optometrist based on the frames we supply.     Q. What are photochromic lenses? A. They are lenses that go dark in sunlight and nearly clear at night. They go darkest when it is bright and cold. When it is hot they will not go quite as dark. We recommend plastic photochromic lenses which are available in grey and brown.     Q. What are polarising lenses? A. Polarising lenses reduce glare from horizontal surfaces. They are very popular with anglers and sailors and are often found on sunglasses (check out our range of non prescription sunglasses.     Q. What tints do you offer? A. We offer a range of different colours for reducing glare with dark (80% absorption), which is a sunglass tint ideal for prescription sunglasses. Non - standard tints are available by special order via our phone line.