Gaze-evoked deformations of the optic nerve head in thyroid eye disease.
Fisher Liam K, Wang Xiaofei, Tun Tin A, Chung Hsi-Wei, Milea Dan, Girard Michael J A
AI Summary
This study found that thyroid eye disease (TED), particularly with proptosis or stiff extraocular tissue, significantly increases gaze-evoked optic nerve head deformations. This suggests a potential mechanism for optic neuropathy in TED.
Abstract
Purpose
To assess gaze evoked deformations of the optic nerve head (ONH) in thyroid eye disease (TED), using computational modelling and optical coherence tomography (OCT).
Methods
Multiple finite element models were constructed: one model of a healthy eye, and two models mimicking effects of TED; one with proptosis and another with extraocular tissue stiffening. Two additional hypothetical models had extraocular tissue softening or no extraocular tissue at all. Horizontal eye movements were simulated in these models. OCT images of the ONH of 10 healthy volunteers and 1 patient with TED were taken in primary gaze. Additional images were recorded in the same subjects performing eye movements in adduction and abduction. The resulting ONH deformation in the models and human subjects was measured by recording the 'tilt angle' (relative antero-posterior deformation of the Bruch's membrane opening).
Results
In our computational models the eyes with proptosis and stiffer extraocular tissue had greater gaze-evoked deformations than the healthy eye model, while the models with softer or no extraocular tissue had lesser deformations, in both adduction and abduction. In healthy subjects, the mean tilt angle was 1.46°±0.25 in adduction and -0.42°±0.12 in abduction. The tilt angle measured in the subject with TED was 5.37° in adduction and -2.21° in abduction.
Conclusion
Computational modelling and experimental observation suggest that TED can cause increased gaze-evoked deformations of the ONH.
MeSH Terms
Shields Classification
Key Concepts5
In computational models, eyes with proptosis and stiffer extraocular tissue had greater gaze-evoked deformations of the optic nerve head than a healthy eye model in both adduction and abduction.
In computational models, eyes with softer or no extraocular tissue had lesser gaze-evoked deformations of the optic nerve head than a healthy eye model in both adduction and abduction.
In one patient with thyroid eye disease, the optic nerve head tilt angle was 5.37 in adduction and -2.21 in abduction, as measured by optical coherence tomography.
Computational modeling and experimental observation suggest that thyroid eye disease can cause increased gaze-evoked deformations of the optic nerve head.
In healthy human subjects, the mean optic nerve head tilt angle was 1.46 0.25 in adduction and -0.42 0.12 in abduction, as measured by optical coherence tomography.
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