Usefulness of the ratio of orbital fat to total orbit area in
mild-to-moderate thyroid-associated ophthalmopathy |
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Authors: | H C Kim S W Yoon H Lew |
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Institution: | 1.Department of Ophthalmology,
Bundang CHA Medical Center, CHA University, Seongnam, Republic of
Korea;2.Department of Radiology,
Bundang CHA Medical Center, CHA University, Seongnam, Republic of
Korea |
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Abstract: | Objective:To identify a useful predictor of thyroid-associated ophthalmopathy (TAO)
from orbital CT images; to evaluate the orbital fat and extraocular muscle
area ratio as a CT-derived measure; and to investigate the correlations
between this ratio and the clinical manifestations in mild-to-moderate
TAO.Methods:Between January 2012 and March 2013, 44 patients with TAO and 23 controls
were studied prospectively. All of the patients underwent ophthalmic
examinations, including clinical activity score, exophthalmometry, clinical
photographs, alternate prism and cover test, duction and version test, Hess
screen test, binocular single vision test, thyroid function tests and
orbital CT. The cross-sectional areas of the four rectus muscles, superior
oblique muscle, optic nerve and total orbit area were calculated in the
coronal view 6 mm posterior from the posterior pole of globe.Results:The cross-sectional area measured on orbital CT showed increased orbital fat
in patients with TAO and an increased orbital fat to total orbit area ratio
(fat/orbit) in TAO with retraction and proptosis. There were significant
correlations between fat/orbit and margin reflex distance 1
(p = 0.022), margin reflex distance
2 (p = 0.013) and the exophthalmometric
value (p = 0.007).Conclusion:The orbital fat to total orbit area ratio (fat/orbit) is a useful diagnostic
index in mild-to-moderate TAO.Advances in knowledge:The orbital CT offers a useful diagnostic index in TAO. |
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