Doi not leave eyewaer in a hot car

Don’t Bake Your Glasses In Your Car

by Marcia Dettloff, OD on July 8, 2012

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.

    Cracks in poly from exposure to alcohol

    Cracks in poly from exposure to 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.

    Correct frame position

    Correct position to lay glasses to protect them against scratches when a case is not available.

  • 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.




1 eyeglasses October 26, 2012 at 6:45 am

Thank you for this very informative Tips for protecting the eyeglasses..
nice post!

2 Amy February 14, 2016 at 2:09 pm

Can i repair my lens if it got ruin due to excessive heat? Or i need to get a new lens. Because i accidently left it in a car. But the glass is wrapped with cloth n inside a box. Still the lens got some weird scratch on it. Is there any way that i can fix it?

3 Marcia Dettloff, OD February 15, 2016 at 12:10 pm

Unfortunately, the lens will have to be replaced.

4 Gallina India June 16, 2016 at 6:12 am

Awesome Information. Lots of People keep sunglasses in their cars. You are share very useful article with us. Keep sharing these types of useful article regularly

Really Nice Post!!

5 Richard Taylor July 4, 2016 at 6:34 pm

I used some plastic cling wrap like Saran Wrap to lightly and gently place around my lenses when I was gluing an earpiece so as to not get glue or acetone on the lenses. I’m just wondering if the cling wrap damages the anti-reflective coating on the lenses.

6 Marcia Dettloff, OD July 15, 2016 at 9:55 pm

I don’t see how plastic wrap would damage the lenses. The completed glasses come from the lab in ziploc-type bags. Excess heat and cleaning AR coated lenses with window cleaner with ammonia are the main source of problems with AR coatings.

7 Barry July 19, 2016 at 2:33 pm

I have a wavy look in the lenses of my prescription glasses that are transitions. It doesn’t really affect my sight I can just tell when looking at them and just wondering if the heat did this?

8 Marcia Dettloff, OD September 2, 2016 at 9:30 pm

It’s hard to say without seeing the lenses. I doubt the lenses have significant distortion if you can still see clearly and comfortably. You might just be seeing the image size and shape shift as you tilt the lens due to the lens power, especially if you have a lot of astigmatism or you have progressive lenses.

9 Roger Stout September 6, 2016 at 8:13 pm

I think my brand-new photochromic, high index eyeglasses suffered heat damage from a campfire. I was wearing them while roasting a weenie, and immediately afterwards noticed I had fuzzy vision through the central dime-sized region. If you look closely, you can now see a sort of ripply texture there. Have you ever heard of this happening?

10 Marcia Dettloff, OD September 14, 2016 at 11:58 am

It sounds like the lens warped or an anti-reflective coating may have crazed. The optical center of the lenses is the thinnest and most susceptible to warping from heat.

11 Scott Knitter December 6, 2016 at 4:00 pm

Oddly, this morning I discovered a small ripple in one of my progressive lenses near the bridge, and this seems to have developed overnight. I tried to wash it off, but it’s a change in the lens. I’ve been doing nothing different with my glasses and don’t recall any spattering from hot grease, or a caustic chemical, nor any contact with heat. I’m thinking it’s time for new glasses but is there anything else that causes these? Before I blame my cat.

12 beanie December 10, 2016 at 9:50 pm

My polarized coating on raybans are peeling of after i ran it under coldwater to clean it, is there a way to repair the polarized coating

13 beanie December 10, 2016 at 9:53 pm

Or is there away to remove the polarise coating without damaging the sunglasses and just using it as normal sunglasses? Thanx in advance

14 ike December 15, 2016 at 7:22 am

I have been using a pair of photochromic eyeglasses. Two years later, I have noticed that despite cleaning them with cloth, they have become blurred and I can barely use them, any explanation? anything I can do about this?

15 Marcia Dettloff, OD December 19, 2016 at 4:10 pm

Unfortunately there is nothing that can be done to repair the lenses. However, I doubt the polarized coating is what is peeling off because they are laminated lenses with the polarized film between two layers of plastic. You are more likely having a problem with the scratch resistant coating or anti-reflective coating coming off. The coatings are warranteed for a certain amount of time (that depends on the coating) so you may want to check with the place where you purchased them.

16 Marcia Dettloff, OD April 6, 2017 at 2:42 am

No you can’t remove the polarized layer. I’m not sure how it can peel off because polarized lenses generally have a polarized film sandwiched between two layers of plastic. Even if you could peel it off, typically all the tint is contained in that layer so the remaining lens wouldn’t have any tint.

17 Marcia Dettloff, OD April 6, 2017 at 2:43 am

Sorry, I have no idea what could cause that other than heat.

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