Because there are two lenses, eyeglasses are always referred to in the plural. Your question should read: Is the noun...not Are the noun...

Glasses are uncountable, it’s always plural. Imagine, it’s two glasses, like pants, although if you’re talking about water glass in plural, you’re going to use 5 water glasses for example. The conjugation it’ll be always with plural, like, my new glasses are great to see!

The words ,,eyeglasses, pants , clothes , and in your sentence ,,glasses,, are always plural and a plural verb should follow

The word glass here is uncountable but it can be countable in other context for example when referring to the glasses we drink from, here glasses is plural