What are thin lenses?
As the name suggests, thin lenses are high index lenses which allow a higher prescription to be packaged in comparatively thinner lenses. The index of a lens refers to how much light it refracts.
Thin lenses are not only lighter, more comfortable and stylish, they are also stronger. That’s why they are recommended for rimless glasses, where strength is of particular importance.
It all starts with light

You may already know that we see things due to the light entering our eyes. We need vision correction (for nearsightedness, farsightedness or both) when our eye lens system doesn’t work perfectly. This makes our eyes unable to focus an image on our retina (think of retina like a cinema screen, on which movies are projected), resulting in blurred vision. Enter prescription lenses! Depending on your power/prescription, these lenses refract or bend light in such a way that its focal point is correctly adjusted, so that we experience clear vision.
Higher the prescription, the more refraction your lenses need - the thicker they will be in case of standard lenses.
High index lenses refract more light, so less material is required even for higher prescriptions.
Why thin lenses?
There are a lot of advantages when you go for thin glasses frames -



Since less material is required, thin lenses are also lighter and more comfortable to wear.
Because of narrow shape and slimmer edges, they can be glazed into a wide variety of glasses. There’s a good, noticeable difference between thin and standard lenses and in most cases thin lenses do not stick out of the frame.
Thin lenses are naturally more aesthetically pleasing compared to bulky lenses. They are streamlined within frames and also avoid the “bug eye look” or fish-bowl effect associated with high prescriptions.
Types of thin lenses
There are a lot of advantages when you go for thin glasses frames

Standard or basic lenses have an index of 1.5 or 1.56.
Thin lenses have an index of 1.6 or 1.63 and are around 20% thinner than basic lenses.
Ultra-thin lenses have an index of 1.67 and are around 30% thinner than basic lenses.
Do I need ultra-thin or thin lenses?
Your lens thickness depends totally on your prescription, frame material and frame style. In simple terms, if you have a combined power above +/- 3 you should consider going for thin lenses, if it is above +/- 6 then go for ultra-thin lenses for ideal glazing and perfect quality lenses.
Acetate, TR90 or Composite Wood frames
Lens thickness | Suitable for prescriptions |
Price |
---|---|---|
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Up to +/- 3 | Free |
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Up to +/- 6 | £27 |
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Up to +/- 9 | £60 |
Since acetate frames are thicker than metal ones, it is comparatively easier to hide around the bevel.
Metal frames
Lens thickness | Suitable for prescriptions |
Price |
---|---|---|
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Up to +/- 2.5 | Free |
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Up to +/- 5 | £27 |
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Up to +/- 9 | £60 |
Since metal frames have more of a thin wire, the lens thickness is more visible.