Stilly, me too. Pairs of cheap glasses everywhere, although I still use the prescription lenses for computer and reading sessions. The cataract surgeon gave me a choice of lenses and I told him my distance vision is good and I have only needed glasses for computer and reading so he kept it that way.

I guess, technically, the "correct" phrase is "I left my glasses at home" but the "forgot" phrase could be a contraction of "I forgot and left my glasses at home". Language changes over time and locations around the world. Teaching ESL students the correct English is good, but they also need to also understand the common phrases being used in their society. As an example, in Oz they would have to know the meaning of "G'day!" and "Goodonya, mate!" to navigate society effectively. LOL