Unfortunateli I cannot give you specific information on the treatment and prognosis for your sisters case without knowing a diagnosis/seeing the scan
There are a number of tumors that can affect the optic
nerveNerve biopsy
Nerve conduction velocity. The most
commonCommon cold ones would be a meningioma of the optic nerve sheath or an optic glioma. Both are relatively benign tumors, that is, they do not spread rapidly or spread to distant areas. However, in teh brain where space is at a premium, any mass can cause problems. Surgery can be difficult in this area, and depeding on the involvement of teh nerve fibers, could lead to blindness in that eye. Many times, we do not operate on optic tumors but observe them over time, and assess visual function formally by an ophthlamologist. Optic tumors are sometimes asscoateid with a condition called neurofibromatosis, which can be checked for. This condition presdiosposes to this and other tumors.
I personally do not know any doctors in the Las Vegas area, but a neurologist or neuro-oncologist at a big center may be the best choice. The brain tumor institute at the Cleveland Clinic is also very experienced in diagnosing and treating similar cases.
Good luck