In this article you will learn about the differences thinner lenses can in regards to the appearance of your lenses (the thickness) as well as how they could influence your vision. How big those differences will be is dependent on the prescription your visual acuity and the lens design was chosen.
This leads to a variety of combinations. In this article, we will focus on general rules on what to expect from thinner lenses.
In general, the higher the needed lens power is in the prescription the more aberration can be expected looking through the periphery of a thinner lens compared to a lens which is optimized for an optimal visual experience. The more the wearer looks through the periphery of the lens the potential for lens aberrations increase.
The question is oftentimes what difference do you want from a thinner lens. Do you expect to get a flatter lens and your eyes should appear more natural in regards to the size? Then you need to go the route with the thinnest lens design available at your optician.
But most wearers of spectacles want both. A big clear visual field of view in combination with thin lenses in their glasses. This is also what most manufacturers do automatically. They produce a balanced lens that will look good in combination with a reasonable clear field of view. Let us talk first about the difference in vision and afterward about the thickness of the lens.
What Is the Difference in Regards to Your Vision?
The lens designs can only be optimized for one situation. In this situation you are looking straight through the lens at an object in front of you. in the reality, of course, you do perform eye movements behind the lens and you might look through the lens in an askew way. However, the perfect prescription is only available to you in an area that is positioned in front of your pupil. This is called the optical center.
By moving your eyes into the periphery of the lens an unwanted lens power is induced. In most cases wearer of spectacles notice this more with extremely thin and flattened lenses in combination with hyperopia (farsightedness). The difference from looking straight ahead and having a clear image to looking more through the periphery and having a blurry image is the result of the unwanted astigmatism.
The more the lens design is optimized for a thinner lens the faster the periphery produces this blurry visual experience. Here in the picture, you can see the difference between a lens design optimized for the best visual experience in comparison to an extremely flat lens design.
When we talk about a thinner lens it is usually a combination of the lens design aspheric, atoric changed base curve in combination with a thinner material. With a thinner material in most cases wearers do not notice a difference. But this is highly dependent on how sensitive the wearer is. In some cases the wearer can spot the difference between a thinner lens and a standard lens material which is thicker.
For example, some people notice color fringes with extremely thin lenses. Those thinner lenses in most cases have inferior quality in regards to the optics. The abbe value is lower and as a result, especially with high prescriptions, some wearers can see colored outlines of objects. In most cases, it looks like a slightly yellow or blue glow around objects and usually appears in bright light. This effect is most common when polycarbonate or the very thin MR 174 is used.
Here in the chart below you can see the difference in abbe values between the different thin lens materials. As you go through the chart you can see the abbe value dropping with an increase in lens index. Or expressed differently the thinner the lens the worse the optical quality.
| Material & Index | Abbe value |
| CR39 (1.5) | 58 |
| Trivex (1.53) | 45 |
| NK55 (1.56) | 42 |
| Polycarbonate (1.59) | 30 |
| MR-8 (1.6) | 42 |
| MR-7 (1.67) | 32 |
| MR 174 (1.74) | 33 |
How Big Is the Difference Between Thinner Lens Materials for Glasses?
Here in the chart below you can see the differences when it comes to the weight reduction and the reduction in thickness compared to the standard plastic CR39 lens material. As you can see in the chart below with an higher lens index the reduction in thickness increases.
| Material & Index | Reduction of weight compared to CR39 | Reduction of thickness compared to CR39 |
| CR39 (1.5) | ||
| Trivex (1.53) | -12% | -10% |
| NK55 (1.56) | -18% | -14% |
| Polycarbonate (1.59) | -23% | -17% |
| MR-8 (1.6) | -24% | -29% |
| MR-7 (1.67) | -35% | -37% |
| MR 174 (1.74) | -50% | -50% |
The data in the chart is correct if you compare the same materials side by side in the same lens design. In reality when you buy lenses features like an asphere oftentimes get added which make the lens even thinner. This is why you can not compare those numbers side by side because in real world examples the numbers could differ form them presented in the chart because of the options the different manufactures give you when it comes to the combinations of lens materials and lens designs.
If you want to know more about thinner lens materials I have an article here for you with real-world examples. After you read this article you will know the differences between glasses that will automatically lead to thinner lenses and those that will look thicker even with thin lens materials.
Yes, you read that right. When the glasses frame is not chosen optimally thinner lenses will not make a big difference. You probably would still disappointed about the result. This is why it is crucial to choose a good shape in the perfect lens size. This way you will be delighted how thin your glasses can look and how light they will be on your nose.
I hope you found the information you were looking for about if thinner lenses make a difference.
I wish you a great day.
