The monomers of polycarbonates are bisphenol A and phosgene. Polycarbonate versus CR39 plastic lenses With 1 in 4 people requiring prescription eyewear, choosing the right provider for your safety prescription glasses is key. Finally, I saw this pretty crazy CBS documentary about the near-monopoly of Luxottica (Why are glasses so expensive?) Trivex is an improvement over Polycarbonate. Weight. The higher the number, the thinner and lighter the lens. I know I'm getting greedy, but will appreciate your advice! I recommend anti-glare/reflection coatings to everyone. These cost an additional $30. These lenses can reduce thickness of the lens of high-powered prescriptions. -- comments? Polycarbonate is also very lightweight and capable of withstanding extreme temperatures, either hot or cold. I'm never going to buy from a brick and mortar again. They also make the lenses lighter and more comfortable. -- never heard those terms before. And most of all, it gets thick quickly, … Below you will find a breakdown of each material so next time you … The 1.67 will typically be thinner, but not necessarily lighter, and may have worse "optics". New comments cannot be posted and votes cannot be cast. Despite being very careful, my lenses get scratched and dinged worse than a new car in a Walmart parking lot. :) Polycarb is amazing overall. I do have a question about the heat.. The refractive index of clear polycarbonate is 1.584. Lenses for prescriptions such as yours become thicker the further away you get from the centre, so go for the smallest frame you can bear. Refractive index refers to the rate at which light bends as it passes through the plastic of the lens. According to that, Optima offers the highest index refractory material (at 1.74) of the major manufacturers, but for safety, you may still want to think about polycarbonate lenses. They are comparable to glasses I have paid $600 for. Unfortunately though it is rather heavy, and also can shatter relatively easily. Perspex and polycarbonate are two such types of … This means the index of refraction would need to be greater than that of polycarbonate and Trivex (>1.60). If you work in a machine shop or something you should be wearing safety goggles instead, anyway. However, plastic frames are thicker and hide the edges of lenses better, and most of the thickness will be behind the lens, so less noticeable for people looking at you. Press question mark to learn the rest of the keyboard shortcuts. Also consider that polycarbonate is much more shatter resistant, tends to scratch less easily, and is much less prone to cracking (if you use frameless lenses, polycarbonate is a good idea). I've been happy with 39dollarglasses.com. Don't be fooled. Chemical Resistance – Polycarbonate exhibits good chemical resistance against diluted acids, aliphatic hydrocarbons and alcohols; moderate chemical resistance against oils and greases. I have to have polycarbonate lenses...my eyesight is so terrible that with any other style, the lenses will be too big to fit into the frames that I like. They are usually between 0% and 5% transmission of these rays. I'm especially curious about the anti-scratch coating. But if you consider the lifetime cost of new polycarbonate lenses versus high index (say, $100 difference, new glasses every 4 years, live for another 40 years = $1000), it's not that much more money for high index (depending your your parameters for that equation). I prefer them for being really scratch and neglect proof. I've bought about 8 pairs over the last few years. Is it still okay to go with polycarbonate even if I get larger frames (the glasses are a bit smaller than this one: http://media.philly.com/images/lalalalallaglasses.jpg)? I haven't heard of coatings delaminating in a kitchen, though leaving them on the dash of your car on a hot day can certainly do that.Happy seeing. The entire process takes only a few minutes. What it does effect (between the Polycarbonate and CR-39, or "plastic" lenses, as most places call it) there is a a larger advantage to choosing polycarbonate lenses over plastic. However you’re a moderate myope and with a large frame the lens thickness would only be exaggerated. Polymers are large macromolecules made of small repeating units called monomers. It also scratches really easily, even with antiscratch on top. Will there be any noticeable visual distortion? Polycarbonate lens material is an impact-resistant material that has a medium index, making it somewhat less thick than standard plastic lenses but thicker than high index. Ultra thin 1.67: These lenses contain a high index of 1.67 and can reduce thickness of the lens of high-powered prescriptions. Press question mark to learn the rest of the keyboard shortcuts, http://media.philly.com/images/lalalalallaglasses.jpg. Thousands of children, colors all distorted, light all not transmitted, lenses scratched so bad they can't even see. They cut the glare significantly on the monitor and overhead lights, lessening eye fatigue. r/AskReddit is the place to ask and answer thought-provoking questions. :). Polycarbonate is a very strong and resilient thermoplastic material. By using our Services or clicking I agree, you agree to our use of cookies. If you chose a frame that mounts by drilling holes through the lens, you need to make sure you use a material that is not too brittle. These tints are available in a variety of colors including, brown, gray, yellow, red, blue, rose, green, and more. They reduce UV-A and UV-B rays from coming at your eyes at 100% density. Polycarbonate, also denoted as PC, is a strong, durable, and tough material. Lens materials do not degrade the quality of the vision in the lens. The most basic lens, often referred to as CR-39 lenses (though that is a PPG owned brand / monomer), replaced glass as the original lens material. Polycarbonate has an index of about 1.56. The lower numbers are classified as mid-index lenses. Or is that not enough heat to cause problems? Mid-index lenses, such as 1.54, 1.56, and 1.57, are thinner than glass, and nearly as strong as CR-39. Plastic lenses can accept tint colors for the people that like a light tint on their lenses. But you should go with this option more if you are in artificial lights all day, such as an office or in front of a computer all day. A high-index eyeglass lens allows people with a stronger prescription to wear a lens that is lightweight and thin. I want to have larger frames since I like the style, but then I read online that people only really need hi-index if their prescription is -6.00 or worse. Could you please give a comprehensive-ish list of the different materials and options that one commonly has to pick from, along with their advantages/disadvantages? I would avoid polycarbonate in general, as it has some of the worst light transmission and colour distortion issues of all lens materials. Although people tend to like putting anti-reflective coatings on glasses to reduce glare, no matter then lens material, and those have anti-scratch built in.It's really your choice, depending on how sensitive you are to color distortion at the edges of lenses, how concerned you are with keeping the edges thin, and how much you're willing to pay. Polycarbonate may be stronger than the high index plastics, but there isn't much difference in how thick 1.60 is from the polycarbonate. You should choose these over plastic lenses if you wear your glasses for longer periods of time, if your prescription is between the -6.00 to +6.00 range. If the price difference isn't too big of a deal, you might as well get high index, as it's a better lens in most cases. I have yet another question here. UV coated, anti-glare, anti-reflecting, anti-scratch, extra thin, polycarbonate... Do these really do anything? If you have any more questions on lenses or the process, feel free to ask me. This will cause the lens coating to de-laminate, causing really fine, close hairline cracks in the coating. So a hi-index lens would be a good idea. Acrylic is also less expensive than polycarbonate and unlike polycarbonate, acrylics can be heated and molded to shape, then heated again while retaining its quality appearance. Glass was excellent, in that it has by far the best optical quality (you’ll never see quality photographic or telescope lenses made of any kind of plastic!). The key difference between polycarbonate and plastic is that polycarbonates are lighter but, much stronger than plastic.. Polycarbonate and plastic are polymer materials. I really appreciate any help! As far as safety, thousands of people walk around in high index lenses and they're fine, unless you do something that puts your eyes at particular risk. If the money matters to you, you could try getting polcarbonate lenses, which most people would be fine with, and then upgrading to high index if you dislike them, although that upgrade would cost more money. Anyone have a take on the overseas sources (e.g., Zenni Optical)? The monomers of plastic depend on the type of plastic; there are two … Polycarbonate has more chromatic aberration that other lenses, but most people don't notice it.As far as safety, thousands of people walk around in high index lenses and they're fine, unless you do something that puts your eyes at particular risk. Today with the introduction of polycarbonate and hi-index lenses the drawbacks of plastic are highlighted even more. It provides a thinner lens for stronger prescriptions than the 1.50 standard-index, 1.53 Trivex, 1.57 mid-index, 1.59 polycarbonate, and the 1.61 high-index lenses. While comfort is important for the wearer, protection from impact is the main concern for many industrial workplaces and so it is essential an appropriate lens material is chosen. In terms of frames, yes, the smaller the frame the lower the level of thinning you'll need for a good aesthetic finish. It is also not easily scratched. I think there is a material around 1.67 that is good for this. High index lenses are made of a plastic material which bends light more than standard CR39 lenses and can therefore be made thinner and lighter allowing for more cosmetically appealing and comfortable to wear glasses.. Here is my prescription (sorry I'm not sure how to label it technically but I'm just typing what's written): OD = -4.00 (Spherical), -1.00 (Cylinder), 006 (Axis) OS = -3.25 (Spherical), -0.75 (Cylinder), 174 (Axis) A picture: https://ibb.co/fkxnhR. Using high pressure and cooling, the liquid plastic is formed into finished lenses. In some instances, yes, you are most likely getting fleeced. Here is a brief comparison of polycarbonate and Trivex lenses to help you decide which lenses might be best for you: Thickness. The lenses are a high-index plastic material. You certainly don't NEED to go with hi index.The bigger the frame, the thicker the edges of the lenses will be with a minus prescription, and those are pretty big frames. Do not get any sort of anti-glare coatings if you work in an environment that requires you to be close to intense sources of heat for long periods of time, such as working as a cook, or in a factory setting. While polycarbonate roofing may not be the best option for an entire house; it is ideal for other structures such as decks, garages, patios, sheds, and conservatories. Acrylic is also easier to crack, while polycarbonate is easier to scratch. It is a lighter alternative to glass and a natural UV filter, so it is often used in eyewear. The anti-glare/anti-reflection are usually the same thing. Other high-index materials are classified by numbers. They are a lot less dense, and they don't chip as easily as a plastic lens. Check your warranty. Since polycarbonate is 1.58 index, it is considered a “mid index” lens. I want my vision to be perfect but also am scared that hi-index lens may not be as safe. Key Difference – Perspex vs Polycarbonate Engineering thermoplastic polymers such as polyethylene, polypropylene, polyvinyl chlorides, polycarbonate, polyacrylates are very popular in the current world due to their excellent combination of physical and chemical properties.However, none of these plastics shows complete perfectness. The super thin 1.67 lenses are recommended for prescription of SPH (-8 to and up). I'm guessing this is bad? Acrylic has a high gloss finish and is more transparent, making it ideal for display cases. Starboard HDPE Starboard is a variety of high-density polyethylene ( HDPE ) created by the King corporation specifically for use in heavily trafficked areas. Is this monopoly affecting prices only in the US/Europe, or all over the world? High index lenses have a refractive index (ability to bend light) of 1.60 or higher. Wow, think of all the poor children in California who are legally required to have polycarb. Avoid unless you're buying safety glasses or sports glasses. High Index Lenses Vs Polycarbonate Hopefully the information here has helped you decide what type of lens is best for you. If you’re debating between getting a high index lens vs aspheric lens vs polycarbonate lens material, here’s what you should know: And given that the most I've ever spent on one frame at zenni is $30 (including lenses with upgrades) it's a very minor gripe indeed. It's a naturally transparent thermoplastic with high impact resistance and excellent heat resistance. Hello, I wanted to make sure that I wasn't being tricked into spending more money than necessary by optometrists (as I have been in the past). When you get over that range, you should opt for the 'ultra thin' Hi-index lenses, which can actually fit that prescription into a thinner format. Some glasses I bought were bigger/smaller than the "dressing room" feature on the right hand side of the page would have you assume. 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