Crazing is the process of anti-reflective coating, or AR, cracking in almost spiderweb pattern. Often times this can be caused by improper cleaning such as using rubbing alcohol, window cleaner, or other harsh household cleaners. Another cause can be extreme temperatures such as welding, working in a deep freezer, or leaving your glasses in a car on an extremely hot or cold day. While crazing can be incredibly frustrating and make it difficult to see through your lens it’s important to remember that through proper lens care it can be avoided. Most warranties will also cover a lens replacement in the event an AR coating crazed within the warranty period due to a manufacturer defect. Anti-reflective coatings are still very important to the quality of the lens and help to improve vision in corrective lenses tremendously by reducing reflections in your lens, reduce eye strain, and assist in making the lens look more cosmetically appealing in photos.
How does heat damage lenses? High temperatures can cause lens to expand or shift at a different rate than the anti-reflective coating on the lens this is what leads to crazing caused by high heat. High heat can also cause damage to the lenses and frames by causing warping or softening in the lens and frame. This is why it’s important to avoid leaving lenses in a hot car or while you are performing activities that cause a high level of heat such as welding or tending to a fire.
How can you prevent crazing? One of the most important ways to prevent crazing is through proper lens care and cleaning. Avoid cleaners high in alcohol or that contain harsh stripping chemicals. By using a cleaning specifically made for lens you can help to keep your lens in great condition for longer. You can also use a lotion-free dish soap such as the original dawn soap with lukewarm water and a lint free cloth to help remove stubborn dirt and debris without running the risk of scratching the lens or damaging the anti-reflective coating.
If you notice a change in the quality of vision you are getting through your new glasses, it’s important to check your lenses to see if you notice a haze on the lens, foggy lenses, or cracks on the anti-reflective coating or lens itself. If you notice these, you can go into your eye doctor’s office to see if the lenses can be repaired or replaced.
Source – https://www.allaboutvision.com/eyewear/eyeglasses/lenses/what-is-crazing/