Figure 2.

Location and Doppler waveform of retrobulbar vessels in Color Doppler imaging (CDI). Central retinal artery (CRA) and central retinal vein (CRV) can be identified in the middle of the optic nerve. Due to their proximity, their signal cannot be separated, and a double waveform is produced. Located on the respective sides of the optic nerve, nasal and temporal short posterior ciliary arteries (SPCA) can be detected generating a uniform arterial pulse representing a small bundle of vessels. Deeper in the retrobulbar tissue on the temporal side of the optic nerve, the ophthalmic artery (OA) flow parameters can be measured.