Table 2:

Optic nerve diameter measurements at each of the retrobulbar and midaspect locations on axial and coronal MRI sections

	Age Group
	<6 mo		6 mo–2 yr		2–6 yr		6–12 yr		12–18 yr		P Value^{^a}
	No.	Mean (mm)	No.	Mean (mm)	No.	Mean (mm)	No.	Mean (mm)	No.	Mean (mm)	P Value^{^a}
Axial
Retrobulbar	13	1.35 ± 0.82	44	2.03 ± 0.30	86	2.20 ± 0.30	109	2.26 ± 0.38	109	2.35 ± 0.40	<.001
Midaspect	9	0.73 ± 0.55	31	1.30 ± 0.33	73	1.46 ± 0.31	114	1.67 ± 0.36	98	1.67 ± 0.40	<.001
Coronal
Retrobulbar	18	1.30 ± 0.83	29	2.08 ± 0.44	72	2.27 ± 0.41	113	2.37 ± 0.44	104	2.33 ± 0.39	<.001
Midaspect	18	0.99 ± 0.66	26	1.53 ± 0.27	69	1.79 ± 0.43	120	1.78 ± 0.38	100	1.87 ± 0.32	<.001

↵a P value assessing the significance of the between-group comparisons using ANOVA.