So you just got your new glasses.
Everything is going well and you love your new look. But you've noticed one (or both) of your lenses is sitting slightly proud of the rear-side of the frame.
Is that normal?
It can be a bit disconcerting if you’ve never seen this before, and it’s a fair question to ask whether something’s gone wrong in the fitting.
A recent message from a customer, Josh, summed it up perfectly. He wrote to say that one lens on his lenses seemed to protrude more than the other, and he wasn’t sure why. If you’ve ever spotted the same thing, this post is for you.
The short answer: yes, it can be completely normal. And there are a few specific reasons why it happens.
Let's dive in.
Why do my lenses stick out?
You're mostly likely to notice this when viewing your glasses from the side, above or from the back. One lens edge can look slightly thicker, or you might see a small ledge of lens material extending beyond the frame. Sometimes only one side does it; sometimes both.
This doesn’t mean the lens is loose, badly cut or wrongly made. What you’re really seeing is likely a combination of prescription physics, frame design, and lens-cutting preferences.
Why this happens
1. Your prescription determines edge thickness
Lenses with minus (-) Sphere powers (used for short-sightedness) are typically thickest at their edges. Add in a minus Cylinder value (which corrects astigmatism) and the edge-thickness increases even more.
This is exactly what happened in Josh’s case. His left lens had a minus Sphere and a minus CYL, which naturally increased its edge thickness. The right lens only had a minus Sphere, so it sat more discreetly within his frame.
If your left and right prescriptions differ (likely), your lens edges will differ too. Completely normal.
2. Some frames naturally make edges more noticeable
At Banton Frameworks, we sculpt our frames with a slightly bevelled front rim. Aesthetically, this gives your frame more depth as the front surface catches light and really accentuates the lovely thick acetate. However, this design detail means that your lenses sit further backwards than it would in a thinner frame front with a 'centred' rim groove.
The trade-off is that the rear edge of strong minus (-) powered lenses can protrude from your frame.
The good news, is that this means the exterior aesthetic of your frame, the front, is kept nice and sleek with no lens thickness protruding forwards. This is the ideal result as it hides the lens thickness towards the interior of your glasses where it's less easily detected by onlookers.
3. Lenses are cut to prioritise the front appearance
When a lens lab makes your lenses, they add a small 'V' shape around the entire edge called a bevel. The lens 'male' bevel is what locates into the 'female' rim of your glasses frame and holds it in place.
On minus (-) power lenses, the bevel is usually moved closer to the front of the lens to make the front surface as clean and flush as possible. That’s where people actually see your glasses, so the focus is on maintaining a sleek, premium look.
The result: the rear surface can sit a touch prouder. Not an error, just deliberate aesthetic engineering.
Is it bad my lenses stick out of my glasses?
In the vast majority of cases, no. A slight rear-edge protrusion doesn’t affect durability, comfort or performance. It’s simply the physics of how lenses behave inside certain frame designs.
The only time this is a problem is if;
- the lens feels loose,
- there are visible gaps between the lens and frame, or
- your lenses are just far too thick or heavy.
If this is the case for you, then your lenses, frame or both may need adjustment or replacement.
How to reduce lens edge thickness
If you’d prefer a slimmer lens profile, there are several options worth considering.
1. Choose a higher-index lens material
High-index lenses bend light more efficiently, so they can be thinner and lighter than 'standard index' lenses. For strong minus prescriptions, this can make a noticeable difference and reduce how much they stick out of your frame.
2. Select a frame with a smaller lens diameter
The larger the lens area, the thicker the edges in a minus prescription. Choosing a frame that’s slightly narrower or shallower in total frame height can have a big visual impact. Opting for short-height frames such as a slim rectangular could be a better option for you.
3. Consider aspheric or double-aspheric lenses
Aspheric lenses use a flatter curvature than traditional spherical lenses. This helps reduce bulging, slim down the profile, and improve the cosmetic appearance, especially for higher minus prescriptions.
Double-aspheric designs take this even further by flattening both front and rear lens surfaces for the thinnest possible look and a wider, more natural field of view.
Aspheric and double aspheric lenses are more costly, but can really slim-down the total thickness and weight of your lenses. To learn more, check out this article.
When it’s not normal
If the lens is visibly gapping, rattling, or shifting inside the frame, that’s not expected. That’s when you should get in touch with your optician, optometrist or the vendor who sold your glasses so re-cutting can be done.
Final thoughts
Lens protrusion is one of those quirks that you won't think about until you see it on your finished frame. But in many cases, particularly with strong minus (-) prescriptions, it’s the nature of how lenses work to correct your vision.
If you're new to ordering glasses or lenses online, it’s worth diving a little deeper into how lens material and lens index affect thickness, weight and comfort. To help you make the best choice, you can read our full guide to high-index lenses. It’s worth reading if you want thinner, lighter lenses that look and feel better.
Hopefully you found this article helpful. Please check out our other eyecare blogs. Thanks for stopping by.