Orbital Morphology for Decompression Surgery in Thyroid Eye Disease Using 2-D Orbital CT and 4 Parameters

Jong Suk Lee; Hwa Lee; Min Wook Chang; Sehyun Baek; Tae Soo Lee

doi:10.3341/jkos.2014.55.9.1267

Journal List > J Korean Ophthalmol Soc > v.55(9) > 1009768

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Lee, Lee, Chang, Baek, and Lee: Orbital Morphology for Decompression Surgery in Thyroid Eye Disease Using 2-D Orbital CT and 4 Parameters

Original Article

J Korean Ophthalmol Soc 2014;55(9):1267-1271.

Published online: 2 September 2014

DOI: https://doi.org/10.3341/jkos.2014.55.9.1267

Orbital Morphology for Decompression Surgery in Thyroid Eye Disease Using 2-D Orbital CT and 4 Parameters

Jong Suk Lee, MD¹, Hwa Lee, MD, PhD¹, Min Wook Chang, MD, PhD², Sehyun Baek, MD, PhD^1,, Tae Soo Lee, MD, PhD³

¹Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea

²Department of Ophthalmology, Dongguk University Ilsan Hospital, Dongguk University College of Medicine, Goyang, Korea

³Nune Eye Hospital, Seoul, Korea

Address reprint requests to Sehyun Baek, MD, PhD, Department of Ophthalmology, Korea University Guro Hospital, #148 Gurodong-ro, Guro-gu, Seoul 152-703, Korea, Tel: 82-2-2626-1260, Fax: 82-2-2626-2024, E-mail: shbaek6534@korea.ac.kr

Received 13 December 2013 Revised 28 February 2014 Accepted 29 August 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To present easily measurable 2D orbit computed tomography (CT) reference data that can be used in a preoperative study for orbital decompression and classification of individual orbital morphologies.

Methods

The study sample was composed of 77 patients with orbital contusion (42 Asian males + 35 Asian females = 154 orbits) who visited the emergency room of the Korea University Guro Hospital from September 2012 to June 2013. Patients with orbital wall fracture, retrobulbar hemorrhage, or eyeball rupture were excluded. Medical records including 2D orbit or facial bone CT were retrospectively reviewed and 4 orbital parameters (orbital length, OL; globe length, GL; GL/OL ratio and 2D cone angle) were measured.

Results

The average OL was 42.53 ± 2.46 mm (35.63-49.09 mm) and average GL was 24.83 ± 1.09 mm (22.75-28.13 mm). The average GL/OL ratio using these 2 parameters was 0.59 ± 0.04 (0.50-0.68). The posterior cone angle was on average, 45.96 ± 5.91° (29.35-60.04°).

Conclusions

Simple measurement of 4 parameters using 2D orbit CT and classification of Asian individual orbital morphology may help in the choice of the most effective surgical technique for decompression surgery in thyroid eye disease patients.

Keywords: 2D orbit CT, Orbital decompression surgery, Orbital morphology, Orbital parameter, Thyroid eye disease

References

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Figure 1.

Globe length: antero-posterior globe length measured at the optical lens level.

Figure 2.

Orbital length: antero-posterior orbital length defined by the distance between orbital apex and the middle of the anterior orbital boundary line. The measurement was performed at the level of the inferior end of the superior orbital fissure.

Figure 3.

Cone angle: cone angle, defined by the angle between the medial and lateral orbital wall. The measurement was performed at the level of the optic canal.

Figure 4.

Distribution of orbital length.

Table 1.

2D orbital reference parameters measured in 154 Asian orbits

Parameters	Values (range)
Orbital length (OL)	42.53 mm ± 2.46 (35.63-49.09 mm)
Globe length (GL)	24.83 mm ± 1.09 (22.75-28.13 mm)
GL/OL ratio	0.59 ± 0.04 (0.50-0.68)
Cone angle (CA)	45.96° ± 5.91 (29.35-60.04°)

Values are presented as mean ± SD.

Table 2.

Distribution of orbital length

Orbital length	Distribution (n, %)
≤40 mm	22 (14)
>40 mm, <45 mm	114 (75)
≥45 mm	18 (12)

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