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Thick Lens Glasses

Why are my glasses lenses so thick? | Do prisms make glasses thicker? | What shape glasses are best for thick lenses?

By Corina Iatisin
Reviewed by Sharlene McKeeman FBDO
Sharlene is a qualified dispensing optician with over 7 years optical experience, a member of the Association of British Dispensing Opticians and registered with the General Optical Council.
Discover the reason behind thick lens glasses and why prescription lenses can vary greatly.

Prescription lenses can vary drastically for each individual, depending on their unique needs. The density of lenses may range from paper-thin to the ‘coke bottle’ effect. But why is this? 

If you have thick glasses, your prescription is likely stronger than most. But what is the purpose of thick lens glasses? Prescription lenses bend the light through curved lenses as it enters your eye. Short-sighted wearers will have lenses that are thicker on the edge and thinner in the middle, while those who are long-sighted will have the opposite.

Why are my glasses lenses so thick?

To understand why you have thick glasses lenses, you need to be aware of your refractive power. The refractive power is the amount that light needs to be bent when entering your eye for you to see clearly. The more light needs to be bent, the higher the refractive power (prescription) will be; therefore, the thicker your lenses will be.


Another point to think about is your glasses’ frame size and pupillary distance. Lens thickness will increase as the frame size increases due to the edge of the lens being utilised to fit the frame. Therefore, the larger the frame, the thicker the lens. A minus RX will be thicker at the edges, while a plus RX will be thicker in the middle.  Your pupillary distance may also change where the thickness occurs if the frame is too large for you.

How thick can glasses get?

How thick the glasses lens will be is determined by a few factors. The material of your lenses contributes to the thickness, as well as your prescription and personal choice. Thanks to new technology, high-index lenses were introduced to help reduce the thickness and weight of the lenses.


High-index lenses are made from a plastic material that allows better light refraction in a thin lens. Many people opt for high-index lenses because they have a more sleek look. If you’re asking yourself, “Do I need high index lenses?” you can discover our thin lenses guide to get a better understanding of what they are and whether they are right for you or not.

DID YOU KNOW?
The article explores the reason behind thick lenses, explaining why prisms make lenses thicker and what are the best frame shapes based on your prescription. 

Do prisms make glasses thicker?

Some eyewear users may experience double vision (diplopia), which requires prism glasses to correct their eyesight. Prism glasses refract the light before entering your lenses rather than when it passes through.

Prism will make the lenses thicker; the higher the prism, the thicker it will be. However, experimenting with various frame styles can help hide the thickness if you feel it is too obvious or bothers you.

Why is one lens thicker than the other?

If you’re noticing that one of your lenses is thicker than the other one, the reason behind that is very simple: different strengths in your prescription. In fact, prescriptions are usually not symetrical: you may be seeing better in one eye rather than the other. Sometimes the difference can be so slight that it is unnoticable; other times, if  the difference is more drastic it becomes more noticeable. 

What shape glasses are best for thick lenses?

Getting a pair of new glasses can be confusing, especially for people with strong prescriptions: certain frame types are not advised as they might affect the overall performance of the glasses. To make the process of shopping for new glasses easier, we have put together a brief guide for both myopic (minus) and nearsighted (plus) prescriptions.

Minus RX Recommendations

Plus RX Recommendations

Now that you have a better understanding of thick-lens glasses and know what frame is best for your prescription, shopping for glasses online won’t be so intimidating or confusing! 

If you want to learn more about trick lenses or lenses in general, visit our Optical Centre. You will find many informative articles on the subject, all thoroughly reviewed by our certified opticians.

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