Characterizing Intraorbital Optic Nerve Changes on Diffusion Tensor Imaging in Thyroid Eye Disease Before Dysthyroid...

Area of Science:

• Ophthalmology
• Neurology
• Radiology

Background:

• Thyroid eye disease (TED) is an autoimmune condition affecting the orbit.
• Dysthyroid optic neuropathy (DON) is a severe complication of TED, potentially leading to vision loss.
• Early detection of optic nerve involvement in TED is crucial for timely intervention.

Purpose of the Study:

• To investigate optic nerve changes in TED patients before DON development using diffusion tensor imaging (DTI).
• To assess if DTI parameters can detect subclinical optic nerve alterations in TED.
• To correlate DTI findings with clinical activity and severity of TED.

Main Methods:

• Diffusion tensor imaging (DTI) was used to measure mean, axial, and radial diffusivity, and fractional anisotropy (FA) in the optic nerves of 20 TED patients and 20 controls.
• Extraocular muscle diameters were measured using computed tomography.
• DTI parameters were compared between TED patients and controls, and between active and inactive TED stages. Correlations with clinical features were analyzed.

Main Results:

• TED patients showed lower mean, axial, and radial diffusivities, and higher FA compared to controls.
• Radial diffusivity was lower in active TED versus inactive TED.
• FA positively correlated with clinical activity, modified NOSPECS score, and extraocular muscle thickness. Radial and axial diffusivity correlated with modified NOSPECS score and exophthalmos degree, respectively.

Conclusions:

• DTI parameters, including FA and diffusivities, reveal optic nerve alterations in TED patients prior to the onset of DON.
• FA is a sensitive indicator of TED activity and disease severity, reflecting subclinical optic nerve changes.