Why are my lenses so thick in my glasses?

Lens thickness. It’s complicated. And it’s a hard pill to swallow.  

Put simply, prescription glasses bend light into our eyes at a corrected angle, so you can see clearly. The worse your eyesight is (i.e. the higher your prescription), the higher the angle that needs to be bent and corrected. Which requires more lens material. 

To bring the thickness down, you can choose to have high index lenses (thin lens options). These lenses are denser, so can bend light better. But there is a limit to how thin you can go given the current lens solutions available on the market. 

Lenses for short-sightedness are concave in shape like the below (the thickness resides on the outside). So the bigger the glasses frame you choose, the thicker your lenses will be given where they are cut to size to fit in the frame.

Concave lens shape for glasses

Lens thickness can also be affected by your pupillary distance (PD) - this is the measurement between the centre of both your pupils. It affects the shape and alignment of your lenses because it relates to where you look through them and dictates the optical centre. In short, the wider your PD, the thinner your lens thickness will be.

PD distance - Diagram showing the distance between the centre of both pupils

So let’s sum up, and look at some key remaining things that can also affect lens thickness:

  • Your minus prescription. The higher your prescription, the thicker your lenses will need to be.
  • Your pupillary distance (PD): the wider your PD, the thinner your lenses. 

Frame choice can also influence your lens thickness:

  • The bigger your lens frame, the thicker your lenses will end up being.
  • The shape of your frame effects where the lens is cut out of the whole lens shape. This one is quite hard to imagine, but if you cut out an oblong shape, then you’ll incorporate more of a thicker section at the sides of the lenses. Naturally, a more rounded lens will help to bring areas of thickness down.
Round optical concave lens with an oblong shape on top

 

At Minus, we know that every millimeter counts in relation to all variables that can influence how thick your lenses end up being. And we’ve built all this knowledge into designing glasses frames that work when combined with your lens prescription. View the collection

If you're feeling brave, you can have a go at using this lens thickness calculator - we would love to incorporate a simulator on our site eventually so it gives you a better idea of how each pair of frames will look with your prescription. It's on our list!