Pink eye is usually caused by bacterial and viral infections, while airborne allergens cause eye allergies.
No, Eye allergies do not threaten your vision. Even so, allergic reactions can negatively impact the quality of life of sufferers.
Eye allergies can last for 4-8 weeks.
In a nutshell, no. Allergies typically affect both eyes and are systemic. One eye might experience a temporary problem if a small amount of allergen gets into it, but this is extremely unlikely.