How should I assess the severity of Thyroid Eye Disease in a patient presenting with ocular symptoms?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 22 August 2025Updated: 22 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

To assess the severity of Thyroid Eye Disease (TED) in a patient presenting with ocular symptoms, a comprehensive evaluation of clinical signs and symptoms is crucial . Initial assessment should focus on identifying key features such as proptosis (bulging eyes), lid retraction, diplopia (double vision), and corneal exposure . It is also important to check for signs of optic neuropathy, as this indicates sight-threatening disease .

Thyroid Eye Disease is typically classified based on its severity and activity . Severity is commonly categorised as mild, moderate-to-severe, or sight-threatening . The activity of the disease, which is often assessed using criteria like the Clinical Activity Score (CAS), helps determine if the disease is in an active or inactive phase . This distinction is important because the effectiveness of different treatment modalities can vary significantly between the initial (active) and chronic (inactive) phases of the disease .

Patients with suspected or confirmed TED, particularly those exhibiting moderate-to-severe or sight-threatening features, should be referred to an ophthalmologist or an endocrinologist with expertise in TED for specialist assessment and management .

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