A-Scan Ultrasonographic Evaluation of Patients with Idiopathic Intracranial Hypertension: Comparison of Optic Nerves

Abstract

Background: To evaluate the interocular optic nerve diameter (ONDs) asymmetry in patients with idiopathic intracranial hypertension (IIH) utilizing the A-scan ultrasound technique. Methods: Thirty-seven patients diagnosed with IIH were recruited from outpatients referred to the University Eye Unit between June 2014 and December 2021. Patients with optic disc pseudoedema or edema caused by other conditions were excluded. All patients with negative neuroimaging for intracranial space-occupying masses underwent standardized A-scan measurement of the OND in the primary gaze and lateral position (30 degrees test). Results: Mean, median, standard deviation, the minimum and maximum value of the two eyes at 0 degrees and the difference between the left and right thicker and thinner ONDs were measured. The two-tailed paired student t-test between the two eyes was performed using SPSS software. A statistically significant difference (p-value <0.001) between the two eyes, without a side prevalence, was found. Conclusions: Due to the differences between the ONDs of both eyes, we propose to use the mean of the ONDs between the left and right eyes at 0 degrees with the standardized A-scan diagnostic technique for a better follow-up of patients with IIH.

Keywords: idiopathic intracranial hypertension; interocular asymmetry; ocular ultrasound; optic nerve; papilledema.

Figure 1

Optic nerve diameter ultrasound. Standardized A-scan ultrasound showing left optic nerve diameter at 0 degrees.

Figure 2

Optic nerve diameter ultrasound. Standardized A-scan ultrasound showing right optic nerve diameter at 0 degrees.

Figure 3

Scatter plot showing the correlation between the right (“x” axis) and left (“y” axis) optic nerve diameter in millimeters, with the eye in a straight gaze position.