I have had glasses for all of my 35 riding years.
Glasses years back actually had glass lenses. The advantage of glass is rain x on the outside reallly works well. Today I have been able to order a set of glasses at Walmart. I then use rain x on the ourside and a scott no fog cloth on the inside. The glasses I purchased have a solid bridge so my eyes do not water at speed in thecold air. This set up is very similar to what I used in the 80"s. Yes my wife does not let me wait this pair of glasses in public
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For the 20 years since I could not find glass lenses I use plastic. Again rain x on the outside and no fog on the inside. The problem is rain x only works so good on plastic. No fog on the other hand works better on plastic. With plastic lenses I tend to buy glasses with nose pads. This allows a small amount of air to pass keeping the glasses from fogging as easily. With the nose pads my eyes will water from the air flow if it is cold. I use goggles over these glasses. I like Oakley OTG L series. Pull out all the foam - Top, bottom, sides. Use a quick strap so I can pull them off and on easily
Helmet. Pull the foam out of the center mouth piece hole. When ever I get a helmet or try new ones I exhale quickly to see if it fogs the glasses. I have had to modify the debri deflectors on a number of helmets since they would take the exhaled air and push it right into my glasses. Helmets made for snowmobiling actually have a deflector that keeps all aire below your nose by sealling on your nose. I have found this too restrictive for dirt biking but you get the idea.