Retinal detachments: Symptoms include new floaters, sometimes described as a “snow globe effect” or spider webs; flashes of light that occur with eye open or closed; and/or a “curtain of vision”, as if you are looking over, around or under something that is not actually there. There is no pain involved with retinal detachments.
This is an emergency and should be evaluated within 24 hours or sooner of the onset of symptoms.

Foreign body: metal foreign bodies can develop rust rings which can cause many long-term consequences including vision loss. Depending on where the foreign object hits the eye will determine the vision symptoms and consequences. The most common symptoms include pain, tearing/watering, vision changes, and redness. This is an emergency which should be treated within 24 hours of the symptoms onset.

Vascular problem: The most common symptoms are a painless loss of vision in one eye with possible previous episodes of transient vision loss. This usually occurs suddenly or over the course of 24 hours. This is an emergency and needs to be evaluated within hours of the sudden loss of vision.