The following tests should be requested (new patient should insist on them) to establish whether one has NAAION, and very fast, since one has only max. 14 days to start a treatment and the earlier it is started the better the potential results to save vision:
1. Fluorescein angiography using indocyanine green dye
This test can show a delay in optic disc filling, which is typical to NAAION. It may also help in differentiating between NAAION and a non ischemic optic disc swelling (edema).
This test may also show the presence of choroidal ischemia. With AAION that may result in peripapillary pallor and swelling (edema) deep to the retina as op;posed to NAAION. So it helps exclude NAAION.
2. Optical Coherence Tomography (OCT)
OCT can show the involvement of different patterns of RNFL (retinal nerve fiber layer) that are typical for different classic visual field defects in NAAION affected eyes.
This test can also help assess the optic nerve head structure and establish whether it has the small cup-to-disc ratio typical for NAAION.