Normative measurements of Korean orbital structures revealed by computerized tomography.
OBJECTIVE
The purposes of this study were to establish criteria for the diameters of normal extraocular muscles, the width of the optic nerve, and the globe position as revealed by CT, and to investigate the effects of age and sex on these parameters in the Korean population.


METHODS
Diameters of extraocular muscles (medial, lateral, superior complex, and inferior rectus), distance from the interzygomatic line to the posterior margin of the globe, width of the optic nerve-sheath complex, and length of the interzygomatic line were calculated for 214 patients on axial and direct coronal CT images, and the effects of age and sex were analyzed.


RESULTS
Normal range for the diameters as given by mean+/-2SDs of extraocular muscles were medial rectus, 2.2--5.4 mm; lateral rectus, 2.1--4.9 mm; inferior rectus, 2.5--5.7 mm; and superior complex group, 2.6--6.4 mm. The mean optic nerve-sheath complex was 4.1 mm and the values ranged from 2.9 mm to 5.3 mm. The mean length of the interzygomatic line was 103.8 mm. The normal posterior position of the globe as here designed was 11.2 mm behind the interzygomatic line (range, 6.4--15.3 mm). All parameters under study were a little larger in males than females. Statistically, however, there was no significant difference between males' and females' results, nor between the various age groups (p>0.05).


CONCLUSIONS
Our CT results may help clinical ophthalmologists to accurately assess enlargement of the extraocular muscles and the optic nerve as well as aiding in the evaluation of exophthalmos.
Lee
J S
JS
Department of Ophthalmology, Research Institute of Medical Science, College of Medicine, Pusan National University, Pusan, Korea. jongsool@hyowon.cc.pusan.ac.kr
Lim
D W
DW
Lee
S H
SH
Oum
B S
BS
Kim
H J
HJ
Lee
H J
HJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009915:Orbit / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D012016:Reference Values; D014057:Tomography, X-Ray Computed