Abstract
BackgroundTo investigate the incidence of absent Bell’s phenomenon (BP) and the relationship between absent BP and inferior rectus muscle hypertrophy and other clinical features in patients with thyroid eye disease (TED).MethodsA total of 104 patients who were first diagnosed with TED between January and December 2014 were included. Inferior rectus muscle area and associations with clinical features of TED and thyroid function test including thyroid specific antibodies were compared between patients with TED with and without BP. The volume of the inferior rectus muscle was calculated by adding up all the cross-sectional areas measured on sagittal CT images.ResultsAmong the 104 patients, 14 had absent BP (13.5%), 12 with bilateral and two with unilateral. There was no significant difference in thyroid function test, presence of TSIs, exophthalmos, or volume of inferior rectus muscle measured in CT scans (P > 0.05). Incidence of diplopia, elevation limitation, and upper eyelid retraction were risk factors of absent BP in TED patients (by logistic regression analysis, P < 0.05).ConclusionsInferior rectus muscle hypertrophy was not the cause of absent BP in TED patients. Fibrosis and tightening of the inferior rectus muscle, lower eyelid, and surrounding orbital tissues, rather than inferior rectus muscle hypertrophy, might be related to absent BP in TED patients.
Highlights
To investigate the incidence of absent Bell’s phenomenon (BP) and the relationship between absent BP and inferior rectus muscle hypertrophy and other clinical features in patients with thyroid eye disease (TED)
BP is absent in 10% individuals, it is more likely to be lost in TED patient with very tight inferior rectus muscle limiting upward movement of the eyeball [9]
The purpose of this study is to investigate the incidence of absent BP and the relationship between absent BP and inferior rectus muscle hypertrophy and other clinical features in patients with TED
Summary
To investigate the incidence of absent Bell’s phenomenon (BP) and the relationship between absent BP and inferior rectus muscle hypertrophy and other clinical features in patients with thyroid eye disease (TED). The clinical features of thyroid eye disease (TED) consist of a variable combination of eyelid retraction, eyelid swelling, proptosis, impaired ocular motility, keratitis, exposure keratopathy, and optic nerve compression [1, 2]. BP is absent in 10% individuals, it is more likely to be lost in TED patient with very tight inferior rectus muscle limiting upward movement of the eyeball [9]. The exact incidence of loss of this reflex and whether BP is correlated with inferior right rectus muscle hypertrophy, Chung et al BMC Ophthalmology (2021) 21:361 tight rectus muscle, or other clinical factors have not been studied
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