That happened to my Dharma once - she got a bit of dust or feather toy in her eye - she squinted a bit and the eye looked watery (like we do if we get something in the eye). At the time I called the ER vet - they told me if the eye wasn't swollen, light sensitive, reddened, or had any colored discharge (like an infection) to keep an eye on her and try to rinse the eye area with sterile water or contact lens saline solution. If any of the other symptoms arose, I was to call them again and get in ASAP. Yes, I did spend a sleepless night chasing Dharma around and trying to look at her eye.
Turned out Dharma was ok - I took her into her regular vet the next morning, as I was just nervous, and had the eye checked thoroughly. The vet said she probably just got something in her eye and between the two of us, we had gotten it out.
Maybe call your ER vet just to run the symptoms by them, but I'm hoping it was just a bit of dust and she's better already.