the good doctor on: If You Can't Take The Heat
Blog #31
If you can’t take the heat…
How can we be talking about heat when we are entering the coldest months of our year? The problem is the need to socialize with each other and yet keep safe and comfortable during COVID. During the summer, we had an easier time maintaining that 2 m distance because we could be outdoors. We need heat to socialize, thus was the bonfire and outdoor space heater discovered. My family has had a few social-distancing bonfires since the temperatures have dropped, birthday bonfires are a thing. They come with risks, however, your clothes get smoke infested, and if you are not careful, you will damage your eyeglasses.
Your spectacles do not tolerate heat very well. A lot of our lenses have very sophisticated antireflection coatings that protect the lenses from minor scratches, and increase light transmission. Problem is, they are sensitive to heat, which causes the coating and the lens to expand at different rates. This expansion can cause the coating to craze or peel off. Unfortunately, there is no way to fix this once it has happened.
Last weekend, there must have been a few bonfires going because we got a number of calls about damaged lenses. Even premium coatings, like Nikon’s Seecoat cannot withstand extreme heat. I speak from experience; several years ago I was burning brush on our property and must have gotten my face too close to the fire, because later I could not see clearly out of my glasses. It took me a while to figure out why (you already know): my Nikon coatings had frosted over, along with a pair of singed eyebrows, definitely too close.
Heat in your car is also a problem. Most new cars have a glasses holder in the roof that pops open to store your glasses. No one asked an optometrist or optician about this design. Never put your glasses in these holders as a car can get into the 200 degree Celsius range on a hot summer day. This will spell disaster for your lenses and coatings and for your polarized sunglasses. If you have to, put them in your glove compartment or better yet take them inside with you.
Enjoy your outdoor socializing around those fires, but keep your spectacle distance from its inviting flames.
Until next week,
The Good Doctor, Dr. Mark Germain, Burlington Optometrist
