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Why Eyeglass Lenses Crack and How to Avoid It

Phoebe Jade

Written By:

Phoebe Jade

Updated: 19 May 2024 •  
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We’ve all been there — it’s another seemingly normal day of wearing eyeglasses, when you suddenly sit on them by accident or sense a distortion in your vision. Next thing you know, you realize your lenses have cracked.
 
It’s a frustrating and all-too-common problem, but don’t despair just yet. In this post, we’re going to get to the bottom of why eyeglass lenses crack and give you some practical tips to prevent it from happening in the future.
 

Common reasons why lenses crack

Before we get into ways on how to prevent lens cracking, it’s important to know what causes it in the first place. Let’s take a look at some of the most common causes.
 

1. Stress fractures

 
They occur when a lens is subjected to constant pressure, such as when we squeeze our glasses too tightly or if the glasses are improperly fitted. This kind of pressure can cause small cracks to form in the lens, which eventually grow and lead to a visible fracture.
 
Also, if your glasses are hit by sudden impact or exposed to a drastic change in temperature, that could worsen an existing stress fracture, which may lead to significant damage.
 
While stress fractures can be hard to detect, they result in lasting damage to the glasses and could ultimately cause the lenses to shatter.
 

2. Accidents

 
We all have moments where we forget our glasses are atop our heads and they fall off, or we accidentally sit on them, causing several fractures on the lenses.
 
person about to sit on eyeglasses placed on couch

While your glasses may seem like they’ve survived when you accidentally sit on them, a few undetectable cracks may have formed on the lenses.

 
Dropping your glasses can also lead to cracks, and it’s not just the dramatic and high-impact drops that you should watch out for.
 
Even those seemingly harmless knocks on soft surfaces can sometimes do more damage than expected. The force of the impact can cause small cracks in the lens or dislodge the frame, which may result in visible cracks after some time.
 

3. Heat-induced warping

 
Leaving your glasses out in the sun or in a hot car for too long can cause the lenses to expand and contract too quickly, resulting in fine cracks that will show up more prominently later. This can be especially problematic during hotter months when glasses have greater exposure to heat.
 
Notably, warping can also occur if you expose your glasses to extreme changes in temperature, for instance going into an air-conditioned room from hot, humid outdoors. Doing this causes your lenses to expand or contract at a rapid pace, resulting in small fractures that could also worsen later.
 

Ways to keep lenses from cracking

Eyeglass lens cracks are never a pleasant experience, and lenses can be costly to repair or replace. Here are some ways to protect your lenses and keep them from cracking:
 
Doing this protects your glasses from accidental impact and scratches, which can cause microfractures to develop and eventually lead to the lens cracking.
 
Also, a case is particularly essential when travelling or commuting, as it protects your glasses from being squeezed by the other contents in your bag.
 
woman putting a pair of eyeglasses into mouqy semi hard case

Keep your glasses in a hard case especially while traveling to prevent other things in your bag from squeezing or banging against them.

 
Hard cases have other benefits, such as keeping your glasses clean and free from dust accumulation, which might cause unwanted smears or scratching over time. By using a hard case, you’re not only protecting your eyeglasses from damage and cracks, but also prolonging their lifespan and ensuring that they function optimally for longer.
 

1. Store glasses away from direct sunlight

 
As mentioned earlier, prolonged exposure to sunlight can cause the lenses to expand and contract quickly, resulting in small fractures that may eventually lead to visible cracks.
 
Storing your glasses in a shady or cool place also helps avoid heat-induced warping and lens cracks. This means avoiding leaving your glasses in the car, especially during hot weather.
 

2. Repair lenses when small scratches surface

 
Small scratches on your lenses might seem insignificant, but they can impact your glasses’ overall structure and lead to visible, larger cracks over time.
 
Home remedies, such as toothpaste or dish soap, may temporarily remove small scratches, but they can also damage the lens coating. Hence, you should exercise caution while doing this.
 
To minimize the risk of scratches worsening, it’s best to visit an optician who can treat scratches professionally. They have specialized tools and lens polishing agents to restore the surface effectively, thereby reducing the risk of a total lens replacement or worsening an existing defect.
 

3. Get scratch-resistant coating for lenses

 
Scratches often pave the way for cracks, but with scratch-resistant coating, there’s an added layer of protection, making lenses more durable and resistant to surface wear and tear. The coating prevents scratches caused by incidental ‘normal’ use, which reduces the need for frequent repairs or eventual lens replacements.
 
With a scratch-resistant coating, you also get peace of mind, especially if you lead an active lifestyle or work in an environment where your glasses might be exposed to more wear and tear than usual.
 
Although some people may shy away from investing in scratch-resistant lenses to keep costs down, ultimately it’s worth the investment as it saves you from frequent visits to repair cracks.
 
P.S. At Mouqy, our eyeglass lenses come included with scratch-resistant coating!
 

Alternative lenses that are less prone to cracking

Some lenses are more built for durability than others, so here some alternatives to look into if you’re in the market for new glasses:
 

Polycarbonate lenses

 
This material is one of the toughest out there and protects well against surface wear and tear. It’s also highly resistant to impact, making it ideal for those who lead active lifestyles or often drop their glasses.
 
person holding eyeglasses by the lens

Polycarbonate lenses are both more durable and comfortable to wear than the average lenses.

 
Polycarbonate lenses are generally lighter than traditional glass lenses, so they’re comfortable to wear for longer periods. That said, while it’s fairly inexpensive compared to other materials, it does scratch more easily over time, so you may need to replace them more frequently if you tend to wear your glasses a lot.
 
Also, polycarbonate still pales in comparison to Trivex and Tribrid (which we’ll talk about next) when it comes to clarity, comfort, and durability. If you’re on a strict budget, however, polycarbonate is your best bet.
 

Tribrid lenses

 
Tribrid lenses offer superior clarity and comfort without sacrificing durability. The material is made of a unique combination of three different types of plastic, making it more resistant to scratches and impact than polycarbonate or Trivex lenses.
 
It’s also lightweight enough to be worn comfortably for long periods. The downside is that it’s slightly more expensive than polycarbonate, though it is cheaper than Trivex.
 

Trivex lenses

 
Compared to polycarbonate and Tribrid, Trivex lenses are the best in terms of clarity and durability. A combination of polyurethane and other materials such as resin, Trivex lenses are particularly resistant to impact and scratches. They are lightweight yet strong, offering top-notch comfort and protection from wear and tear.
 
Due to its characteristics, Trivex is the priciest of the three materials mentioned here. If you’re looking for lenses that will go the distance and minimize lens replacements, Trivex is a good call.
 
P.S. All these lenses are available at Mouqy!
 

Cracked lenses can be prevented!

Eyeglass lenses can crack for various reasons, whether it’s just regular wear and tear or sudden impact from falling. While it’s not always preventable, you can still take measurements to reduce the risk by getting durable lenses and keeping your glasses stored in hard cases.
 
For more tips on how to take care of your glasses, head over to our guide here. You can also learn how to clean them at home to help them look good and work well for longer.

Phoebe Jade

Written by:

Phoebe Jade

Phoebe is a registered nurse, licensed teacher and writer who's passionate about creating content that educates and inspires.