Ocular Hemodynamics in Acute Nonarteritic Anterior Ischemic Optic Neuropathy Compared to Normal Tension Glaucoma.

PURPOSE: To evaluate ocular hemodynamics in patients with a disease believed to be related to a chronic vascular damage (i.e. normal tension glaucoma, NTG) in comparison to an entity with an acute ischemic impact on the optic nerve (i.e. acute nonarteritic ischemic optic neuropathy, NAION).

METHODS: Blood flow velocities (peak systolic velocity (PSV), end-diastolic velocity (EDV)) of the ophthalmic artery (OA), central retinal artery (CRA) and nasal and temporal posterior ciliary arteries (PCAs) were measured via color Doppler imaging (CDI). Resistive index (RI) of all vessels was calculated (PSV-EDV/PSV). 41 patients suffering from acute NAION (onset of symptoms <10▒d) and 64 age-matched patients suffering from NTG were included in this prospective study.

RESULTS: No significant differences were recorded for either age or intraocular pressure in-between the two groups. Systolic blood pressure was significantly higher in the NAION group, whereas no significant differences were recorded for the diastolic blood pressure. Only three CDI parameters were found to differ significantly. The PSV (P<0.005) and EDV (P<0.02) in the CRA were significantly higher in NTG patients. Furthermore, the RI in the OA was significantly higher in the NAION patients (P<0.005).

CONCLUSION: Decreased blood flow velocities in the CRA and a higher RI in the OA can be recorded in NAION patients as compared to NTG. No differences regarding the PCA's velocities were recorded. Ocular hemodynamics are suspected to play a critical role in NAION and NTG, whereas the blood flow disturbances appear to be more severe in NAION than in NTG.