We all want to look our best and our eyeglasses might be one of the best dual-purpose fashion accessories we wear! When it comes to eyeglasses two constants require our attention: Getting the best possible vision correction and, getting the best value for our money. If we choose the right lenses for the job then we’re free to choose the best frame color, material, or shape that makes us look our best but, picking the right lens for our eyeglasses ties all the other shopping together.
The vision correction measured in our exam and shown in our prescription dictates the minimum choice in eyeglass lens materials. Each lens material has limitations on how much it can correct our vision. These practical limitations are understood by your optician or optometrist. They can help you make the best choice between cost and appearance and getting the thinnest lens possible. Your goal first and foremost should be the goal of obtaining optimum vision and that is accomplished by choosing the right lens for the job. If your Rx allows choices in lens material the following table will help you choose the best lens material for your frames and help you accomplish the thinnest lenses and your best look, within your budget.
There are several types of plastic in use in eyeglass lenses today. They are listed (below) in the order of their thickness, with standard plastic resulting in the thickest lens profile compared to the others. Also shown is the “index value” for the lens material. The index value of a lens roughly equates to its thinness and can be used as a guide in choosing lenses. Your optician or optometrist will usually help you choose the right lenses but when there is more than one lens material capable of solving your prescription, it is best to choose the one that yields the best cost to benefit ratio for solving your Rx. It might make sense to spend more to get a thinner lens in your glasses if you have a higher power Rx. That said, some frames do better at concealing thick lenses than others so consider your frames as part of the lens solution. If you need your glasses for work or sport or avocation, then we suggest either Trivex or Polycarbonate lens material due largely to superior impact resistance.
As lens material gets thinner, the index value gets higher and, as the lens index value goes up the cost of the lens material goes up too. If you don’t need the thinnest lens material to solve your Rx, choose a lens that looks good in your frame. Small differences in lens index value are barely noticeable in most cases when you select the right frame. Buying a more affordable lens allows you to buy a better frame or buy an extra pair of glasses with your savings. The best advice is to buy the lens material that gives the best balance of cost and thinness that is capable of solving your Rx. Any qualified optician or Optometrist will have the ability to help you choose the right lens. You may also wish to consider ways to minimize lens thickness that cannot be avoided due to your Rx requirements.
Here is a rundown on the lens index value, approximate reference cost, and common material attributes. This will help provide enough information to make an informed judgment on your lenses from a cost and benefits standpoint and help you justify buying a higher index lens for your glasses when needed.
Material: Standard Plastic CR39
Index 1.49/1.50
Reference Cost $26
Comments: Best optical quality, lowest cost, for low power Rx needs. Tintable.
Material: Trivex
Index: 1.53/1.54
Reference Cost: $85
Comments: Best impact resistance, excellent optical quality, UV resistant.
Material: Plastic Mid Index
Index: 1.56
Reference Cost: $36
Comments: 22% thinner than CR39, cost-effective, UV protection
Material: Polycarbonate
Index: 1.58
Reference Cost: $36
Comments: Best impact resistance, good optical quality, UV resistant.
Material: Plastic High Index
Index: 1.60/1.61
Reference Cost: $55
Comments: 30% thinner than CR39, OK for medium Rx, UV protected, aspheric available
Material: Plastic Very High Index
Index: 1.67
Reference Costs: $90
Comments: 39% thinner than CR39, UV protected, aspheric available, popular
Material: Plastic Extra High Index
Index: 1.70
Reference Cost: $175
Comments: For high power RX. Similar to 1.74 Index. UV protected. Costly.
Material: Plastic Ultra High Index
Index: 1.74
Reference Costs: $175
Comments: 50% thinner than CR39. Expensive, UV protection, available as aspheric. For high power, Rx provides thinnest edges and a flattest front lens profile.
The costs referenced above are for comparison of the differences of varying materials only and should not be relied upon as a standard by which to purchase eyeglass lenses from any provider. In the context of buying the best eyeglass lens for your needs, the lens cost differences are helpful in the larger conversation about which material can best suit your eyeglass needs as all things are considered.