Optic canal location by computed tomography.

The aim of this study was to provide anatomic data for optic canal decompression. One hundred twenty people (55 males and 65 females) were involved in this study anonymously. Twelve parameters are measured in computed tomography: P1 is the nasal bone tip; P2 is the middle point of tuberculum sellae; P3 is the root of columella nasi; P4 is the cranium end of the optic canal; P5 is the orbit end of the optic canal; P1' is P1's projection on L2; L1 is the line that links P1 and P2; L2 goes through P3 and parallel to L1; L3 is the bisector of right and left and goes through P1. The distance between LI and L2 was 30.47 ± 3.71 mm. The distance between P3 and P1' was 11.66 ± 2.82 mm. The medial canal wall length was 10.64 ± 1.10 mm on the right and 10.51 ± 1.07 mm on the left (P = 0.001). The distance between P1 and P4 was 66.74 ± 5.97 mm. The distance between P1 and P5 was 73.04 ± 6.33 mm on the right and 72.82 ± 6.33 mm on the left (P = 0.004). The distance between P5 and L3 was 6.62 ± 1.33 mm. The distance between P4 and L3 was 12.26 ± 1.63 mm. The distance between P3 and P4 was 75.82 ± 4.63 mm. The distance between P3 and P5 was 82.87 ± 4.60 mm on the right and 82.25 ± 4.86 mm on the left (P = 0.003). The angle between P1P4 and L3 was 12.26 ± 1.63 degrees. The angle between P1P5 and L3 was 5.28 ± 1.13 degrees. The angle between P3P5 and P3P4 was 5.80 ± 0.97 degrees. These results provide a precise location of the optic canal.