Objective: This study aims to evaluate and compare the proximal, medial, and distal segments of internal carotid artery (ICA) peak systolic velocities (PSV) in patients with nonarteritic anterior ischemic optic neuropathy (NA-AION) in one eye against the contralateral side with normal eye findings using doppler ultrasound.


Methods:  This is a single-center,  prospective, case control study of five patients with unilateral NA-AION.  The peak systolic velocity (PSV) of the proximal, medial, and distal segments of the ICAs on both sides, one side with NA-AION while the contralateral side had normal eye findings, were compared and analyzed.


Results: Four females and one male with a mean age of 59 years (SD = 17 years) were included. PSV of the ICA was measured in three segments: Proximal (PICA), Medial (MICA), and Distal (DICA). Mean PSV of eyes with NA-AION was 143cm/sec (SD= 177cm/sec), 159 cm/sec (SD=189 cm/sec), 98 cm/sec (SD=34cm/sec) for PICA, MICA and DICA respectively. Mean PSV of contralateral side without NA-AION was 95cm/sec (SD= 72cm/sec), 101 cm/sec (SD=53cm/sec), 140cm/sec (SD=60 cm/sec) for PICA, MICA and DICA respectively. There was no statistically significant difference between the two groups along the three segments (T-test PICAp=0.369, MICAp=0.402, DICAp=0.112).


Conclusion: Mean PSV was higher in eyes with NA-AION at the proximal and medial segments of the ICA, while it was lower at the distal segments compared to the contralateral non-NA-AION side.