Corneal abrasion can be visualized via flourescein, and is recognizable by distortion of the corneal reflex. Visual acuity is usually normal (unless the abrasion crosses the central visual axis).
The history may include trauma, photophobia, blepharospasm, and unconsciousness.
Flouroscein uptake where there are damaged or lost corneal epithelial cells.
A corneal foreign body is similar, but differences include:
History detailing a dusty, machine-related environment.
Sensation of foreign body against cornea
Reactions to foreign body:
Rust ring (if foreign body is metallic and present for hours to days)
I guess the two are pretty similar, you just have to do the all the work-up until you figure out which one. A patient w/ a corneal foreign body may also have a corneal abrasion and a patient w/ a corneal abrasion caused by a foreign body which may have been dislodged. Chicken or the egg syndrome.