Lorie, shame on the ER folks for just checking for glaucoma! I have done some reading on "temporary loss of vision, with no other symptoms" which you have described. I have had TIA's and a stroke. Both have other strange symptoms associated with the loss of vision or visual disturbances. Like a wierd, numb type headache, and certain feelings because your brain is involved/affected. (I think I know how the descriptive term "numbskull", came about. Remember the 3 Stooges calling each other this?). You should see an ophthalmologist in the future, but first I would try to see a cardiologist, or a neurologist that specializes in strokes, soon. I have found 1 condition that causes temporary blindness in one eye, with apparently no other associated symtoms.

Amaurosis Fugax

Amaurosis fugax refers to a temporary black-out of vision. This is usually affects one eye, is painless, and is often described like a "shade coming down over the vision" of that eye. The black-out may last minutes, and then the vision returns. The problem can recur in the future, and could affect either eye. Most commonly, this happens in older people with arteriosclerosis and possibly vascular disease, and is due to small clots breaking off of the walls of arteries and then lodging in the vessels of the eye. The clot obstructs the blood flow to the retina, and the vision blacks-out. When the clot breaks up, the blood flow returns, as does the vision. The source of the clot (or embolus) is usually from the carotid arteries leading up the neck to the brain, or from the heart. The embolus may be a cholesterol crystal, a calcium deposit, or a true blood clot. This problem falls into the same category as "transient ischemic attacks" (or TIA's), which may herald a stroke. Vascular evaluation and possibly anticoagulation (use of blood thinners) is indicated for this problem.