Along with children, pets, DVDs make sure you don’t leave your eyeglasses in a hot car in the summer. Temperatures in the car can reach up to 200 degrees. It takes much less than that to damage your glasses.
While all glasses are susceptible to heat damage, plastic frames are more vulnerable than metal frames. Heat is what softens the frames, allowing us to adjust them to fit properly. When left in a hot car, especially if they are squeezed into a tight fitting case, the heat can warp the temples (earpieces), flatten the frame front, loosen the embedded hinges and/or expand the frame making the lenses loose.
Lenses are damaged by the heat too. The polaroid film used in polarized sunglasses can be damaged by excessive heat. Expansion and contraction of the lenses with temperature extremes can cause warping of the lenses resulting in poor optical quality. Anti-reflective and scratch resistant lens coatings can also expand at a different rate than the base lens material causing the coatings to crack or craze. While newer premium coatings are more tolerant of heat, even those can fail when exposed to the extreme heat.
Here are some other tips for protecting your eyewear investment:
- Always rinse your glasses with warm, not hot, water before cleaning so you aren’t grinding abrasive dust and dirt into the lenses surface. Dry them with a clean, soft, lint-free cloth. If you can’t rinse them first , cleaning with a microfiber cloth will help prevent scratches. But keep the cloth in a protective case and clean it regularly. I have seen many lenses ruined by conscientious patients that wiped their lenses with a microfiber cloth that had abrasive debris in it.
- Diluted Dawn dish detergent works great for cleaning lenses, especially if they have an oily film. If you use eyeglass cleaners make sure they are designed for anti-reflective (AR) coatings and don’t have alcohol or acetone. Many household cleaners, including Windex, can damage the coatings or discolor the lenses.
- Alcohol can ruin polycarbonate lenses. The surface of the polycarbonate lenses have a protective film but the edges and any drilled holes are untreated. If they are exposed to alcohol, fractures can appear in the lenses days or even weeks later. As an example, the cracks in this polycarbonate bottle tray developed over a 2 week period after a few drops of alcohol dropped on it. Since many patients don’t realize they have polycarbonate lenses it’s best to avoid using any cleaner that contains alcohol.
- For the best protection against scratches, dents and rear end collisions, store your glasses in a hard case. If you don’t have a case, the next best thing is to fold them and lay them with the lenses facing up or lay them open and upside down with the top rim of the lenses touching the surface. That way the front lens surface isn’t rubbing against anything. Please don’t lay them face down where they will get scratches right at the peak of the lens, which is right smack dab in the center of your vision when you’re wearing your glasses. And if you lay them down with the bottom of the lens rim touching the surface they easily tip over and end up with the lenses rubbing the surface.
- Whatever you do, please don’t put unprotected glasses in your purse or your shirt or pants pocket. There isn’t a scratch resistant coating in the world that will protect your glasses under those circumstances and the frame will most likely get bent out of adjustment and/or and damaged.
Quality eyewear is a major investment but if you take care of it properly, it will provide excellent comfort and vision for years.