I have inflammation, tearing and pain in one eye, possibly related to eating one cup of cashews the night before?

No: It is probably un-related to eating a cup of cashews. You should see a doctor to get checked for an infection, corneal abrasion and more serious things like glaucoma.

Likely not: Assuming you are not allergic and unless you got something in your eye the nuts are not the issue. It sounds like you may need a doctor to look at it to evaluate for infection or other problems.

Allergy : Having symptoms in only one eye does not sound like allergy due to eating cashews. Usually food related allergies will give symptoms in mouth or lips, or even in gut, but not tearing in one eye. This could be infection and if you have pain, troubles seeing with that eye, see an M.D. soon!

Probably not: Allergic reaction should involve both eyes . Inflammation , pain and watering in one eye would be due to something else, please consult a doctor.