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As someone that works in the eye field, I get asked pretty frequently how to prevent glasses from fogging up with a mask on. Here are some tips (a thread):
First trick: pull your mask up a little higher and use your glasses to weigh it down so air doesnât come up the top when you exhale.
#2: Move your glasses down a little bit so your lenses are farther away from the air flow. This only works with glasses that are single vision near vision only (reading glasses) or distance vision only. Not a good idea if you have progressive bifocals.
#3: use athletic tape to tape down the top of your mask to keep the airflow from going up. Donât use if you have sensitive skin.
#4: Use an anti-fog microfiber cloth like this one! You can find them for $15 on http://theeyebar.com . This one has 200 uses. People that do skiing and snowboarding have used products like this or anti-fog spray for years. Some anti-fog sprays can irritate your eyes and skin.
#5: use lukewarm (NOT HOT) water and dish soap, and dry with a clean microfiber cloth. This creates a film over your lenses to prevent your hot breath moisture from clinging. Not recommended if you have protective/anti-reflective coating on your lenses, as it can strip it.
#6: lather your lenses with non-fragrance shaving cream, rinse with lukewarm water, and dry with microfiber cloth. Medical professions have been using this trick and #1 for years. Also not recommended if you have protective/anti-reflective coating on your lenses.
#7: Consider switching to wearing contacts if you donât want to do all of this or if fog continues to be an issue.
I hope some of these tips will be helpful for you guys! 
