Table 1.

Measurement of the optic canal cross-sectional area (OCA) at the orbital opening.

	NTG patients		OCA (mm2)		Controls		OCA (mm2)
N	Age f	Age m	Right	Left	Age f	Age m	Right	Left
1	45		–	14.9	44		–	15.5
2		45	13.7	12.9		48	16.7	17.1
3		50	20.7	19.0		52	18.7	18.2
4		51	18.4	21.0		53	21	19.0
5	52		–	17.1	51		–	18.9
6		52	18.1	17.9		54	19.7	18.7
7	53		8.9	8.3	53		17.8	17.1
8		53	12.5	12.0		58	24.8	20.5
9		55	17.6	17.6		58	22.9	19.8
10	55		15.6	14.5	53		15.2	15.5
11	57		10.8	11.4	53		18.1	18.4
12	58		10.9	14.1	55		15.6	13.9
13	58		7.7	8.2	57		18.7	20
14		59	13.3	–		58	16.3	–
15	60		10.6	11.9	60		20.6	19.2
16		61	19.9	18.5		61	20.2	19.8
17		61	–	14.0		61	–	19.5
18		63	–	13.1		65	–	15.0
19		63	–	16.8		65	–	15.7
20	64		15.8	14.2	61		19.7	20.4
21	64		15.6	13.0	62		20.8	16.7
22	64		19.3	22.4	62		17	19.8
23		64	14.1	15.9		65	19.7	19.5
24	65		11.4	14.5	65		15.4	16.2
25	65		12.6	14.2	66		21.8	22.6
26		65	14.5	11.4		67	16.2	12.8
27	66		10.9	14.1	66		16.8	15.7
28	67		–	10.6	67		–	20
29	68		14.9	–	68		18.5	–
30		69	15.2	15.2		67	21.0	19.5
31	69		15.7	–	69		16.9	–
32		71	11.3	10.9		73	20.2	21.3
33	72		13.0	12.0	71		17.4	13.1
34	72		13.6	12.3	72		17.7	19.5
35		73	22.0	–		74	16.7	–
36	73		17.6	14.7	73		17.8	20.5
37		73	13.3	12.1		75	15.7	17.3
38		74	12.3	19.8		77	19.7	18.6
39	74		17.4	14.1	73		16.8	17
40	75		–	20.3	76		–	20.2
41	75		12.4	14.0	78		20.2	18.1
42	76		13.0	14.2	79		19.8	19.6
43		76	13.6	12.0		77	13.6	15.3
44		77	10.5	10.8		78	22.7	20.3
45	77		11.2	11.2	79		20.2	22.1
46		78	–	11.7		78	–	16.3
47		79	12.0	13.0		79	23.5	22.1
48	79		12.3	12.9	80		16.3	17.2
49	80		9.3	9.6	81		16	16.5
50		80	18.5	18.5		81	17.4	16.5
51		81	20.0	21.8		82	19.7	17.5
52	83		13.2	12.6	83		23	21.5
53		85	23.2	19.2		83	19.0	21.4
54	86		–	15.2	83		–	17.6
55		88	17.7	17.9		88	11.4	12.3
56	91		11.9	13.1	92		15.5	14.9
Mean ± SD	68.1 ± 10.7	67.2 ± 11.8	14.4 ± 3.6	14.5 ± 3.4	67.7 ± 11.5	68.3 ± 11.1	18.5 ± 2.7	18.1 ± 2.5

Measurement of the optic canal cross-sectional area (OCA) in square millimeters at the orbital opening defined as the first over 360° visible bony structure from the orbital side where the optic nerve (ON) enters through the OC. Age for male (m) and female (f) in years.

NTG, normal-tension glaucoma; OCA, optic canal cross-sectional area; SD, standard deviation.