Transorbital Sonography in Acute Optic Neuritis: A Case-Control Study

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Fig 1.
Transorbital sonography in optic neuritis. A–C, Sonographic examinations of the eye are performed in B-mode imaging in a control subject. A, Optic nerve sheath diameter in the control eye is 3 mm behind the papilla (1) (dotted arrow) in an axial plane showing the optic nerve (2) in its longitudinal course. The dotted arrow (3) denotes the ONSD. B, B-scan shows an optic neuritis increase of ONSD (left, 6.8 mm). C, In patients with optic neuritis with disc swelling, optic disc elevation is gauged between the fundus and the dome of the papilla.
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Fig 2.
Optic nerve sheath diameter and delay from symptom onset. Correlation between the delay of the transorbital sonography examination (days from symptom onset) and optic nerve sheath diameter in the affected eye (r = −0.42, P = .06).

Clinical and sonographic features of patients with optic neuritis and healthy control subjects

Characteristic	ON	Controls^{^a}	P Value^{^b}	ON-MS	Isolated ON	P Value^{^c}
No. of patients	21	21		11	10
Age (mean) (SD) (yr)	30.3, 10.7	34.2, 8.7	NS	26.9, 9.5	34.0, 11.1	NS
Time to US examination: (median) (IQR) (days)	5, 3–7			7, 3–10	4, 3–7	NS
BMI (mean) (SD) (Kg/m²)	24.6, 4.8	23.6, 4.1	NS
Optic nerve sheath diameter (mm)^{^d}
Affected eye (median) (IQR)	6.3, 5.9–7.2	5.2, 4.8–5.5	<.0001	6.2, 5.8–7.8	6.3, 5.9–7.0	NS
Fellow eye (median) (IQR)	5.5, 5.1–6.2	5.2, 4.8–5.5	NS	5.5, 5.0–6.2	5.6, 5.1–6.4	NS
Optic nerve diameter (mm)^{^e}
Affected eye (median) (IQR)	3.0, 2.8–3.2	2.7, 2.5–2.8	.001	2.9, 2.8–3.0	3.1, 2.8–3.2	NS
Fellow eye (median) (IQR)	2.9, 2.8–3.1	2.7, 2.5–2.8	.009	2.9, 2.7–2.9	3.0, 2.8–3.2	NS
VEP amplitude (μV)
Affected eye (median) (IQR)	5.2, 2.2–12.2			7.1, 2.2–12.2	4.0, 2.6–9.3	NS
Fellow eye (median) (IQR)	8.4, 3.2–11.5			4.5, 2.8–8.7	11.1, 9.1–15.1	NS
VEP latency (ms)
Affected eye (median) (IQR)	124, 115–139			119, 115–128	134, 119–142	NS
Fellow eye (median) (IQR)	107, 103–114			104, 103–114	108, 106–113	NS

Note:—IQR indicates interquartile range; ON-MS, optic neuritis in patients with prior relapses of multiple sclerosis; US, ultrasound; BMI, body mass index; NS, not significant.
↵a The average value between the right and left eye was used as a measure of OND and ONSD in healthy controls.
↵b Level of significance at .01, according to the Bonferroni correction for multiple comparisons.
↵c Level of significance at .006, according to the Bonferroni correction for multiple comparisons.
↵d The comparison of the affected and fellow eye was significant (P < .0001) in all ON, ON-MS, and isolated ON.
↵e The comparison of the affected and fellow eye was not significant in all ON, ON-MS, and isolated ON.