Hi J.,
My son was diagnosed with ocular motor dysfunction and convergence dysfunction last year. This severely affected his depth perception and his ability to focus on things within a 6' range or so. We started vision therapy in August and we have seen very noticeable improvement, so much so that the optometrist we visit says that we might be able to take a break on it for a while.
(I should add that he first was diagnosed by an ophthalmologist, we later found an eye therapist closer to home who is an optometrist but trained through the first doc's clinic.)
When we started, my son couldn't cross his eyes; now, we've worked a lot on convergence and have seen great improvement in this area. As for the ocular motor dysfunction, he will have to deal with this all his life. His eyes get tired easily, so we do 'eye exercises' to provide strengthening for focusing and to give his brain/eye good biofeedback on how things feel when they are working correctly. We did a lot of tracking exercises-- things like rolling marbles back and forth, under objects--so that when they came into his line of sight, he'd have to focus and track them and catch them in a cup. We played catch outside a lot, which helped. Many of the exercises were very challenging at first, and then grew to be fun as his eyes strengthened and gained more experience having to focus on moving objects which came toward him.
I would strongly encourage you to give therapy a try. It's so hard not to be able to see the board, and you say it's affecting her reading; I'm thinking it's worth a shot. Eye therapy is not endorsed by the American Academy of Ophthalmologists, and our son's eye doctor is very conservative in his assessment of what eye therapy can and cannot do, yet he agrees that it can help 'some' until my son is old enough for a prescription, if one is warranted. (His vision is 20/20 as well.)
Here is a resource you might check out: PAVE (Parents Active for Vision Education)
http://pavevision.org/
Vision disabilities are pretty serious and can affect other aspects of schooling/learning, not just grades or performance. My son went into K with a 504 plan so that his teacher would understand what to look for when his eyes were tired (his behavior changes, we wanted this addressed properly, not as misbehavior but that he needed a break-- kids with eye issues are often labeled as lazy or 'not trying' when their eyes get tired so much faster than typical kids' do.) Knowing more means you can better help your girl.