Overview
This lecture covers the diagnosis, clinical and radiological evaluation, and grading of Thyroid Eye Disease (TED), focusing on key features, risk factors, diagnostic criteria, imaging, and commonly used grading systems.
Introduction to Thyroid Eye Disease (TED)
- TED, also called Graves Orbitopathy, is an autoimmune inflammatory disorder of the orbit associated with Graves disease.
- It is the most common cause of both bilateral and unilateral proptosis (eye bulging).
- TED results from orbital fibroblast activation leading to glycosaminoglycan deposition, orbital expansion, and venous congestion.
Risk Factors and Pathogenesis
- Endogenous (non-modifiable) risk factors: genetics, age, male sex.
- Exogenous (modifiable) factors: smoking (most significant), thyroid dysfunction, high thyrotropin antibodies, radioactive iodine treatment.
- Patients may be hyperthyroid (30%), hypothyroid (30%), or euthyroid (40%) at presentation.
Clinical Diagnosis and Presentation
- TED is diagnosed clinically; lab tests are not required for diagnosis but help monitor thyroid status.
- Key signs: eyelid retraction, infrequent blinking (Stellwag sign), lid lag (von Graefe sign), lower lid lag (Griffith sign), temporal conjunctival injection (Gifford sign), paralytic extraocular muscle signs (Ballet sign).
- Symptoms: tearing, sandy sensation, discomfort, retrobulbar pain, photophobia, and double vision.
Examination and Monitoring
- Assess visual acuity, color vision, pupils, cornea (for exposure and tear film deficiencies), IOP in three gazes, and optic disc status.
- Measure eyelid position (MRD1, MRD2), proptosis (with Hertel’s exophthalmometer), ocular motility, and soft tissue involvement.
- Soft tissue signs indicate disease activity.
Disease Activity and Grading
- Disease activity must be determined at presentation using standardized scores.
- Rundle’s Curve illustrates the phases of disease activity and severity.
- Grading systems:
- NO SPECS: Grades signs and symptoms from none to sight loss.
- VISA: Vision, Inflammation, Strabismus, Appearance.
- Clinical Activity Score (CAS, EUGOGO): Scores pain, redness, swelling, progression of proptosis, motility, and vision (score ≥3 suggests activity).
Imaging in TED
- Imaging is required when diagnosis is uncertain, optic neuropathy is suspected, or before decompression surgery.
- CT is the preferred imaging for evaluating muscle/fat involvement and surgical planning.
- On CT: muscle belly enlargement with tendon sparing is classic for TED.
- Barrett’s Muscle Index (sum of medial and lateral muscle widths/orbital width >67%) suggests optic neuropathy.
- MRI helps detect disease activity due to inflammatory changes (hyperintensity on T2).
Management Approach Overview
- Active TED: initiate medical (immunosuppressive) therapy.
- Inactive TED: observe or consider rehabilitative surgery based on symptoms (proptosis, diplopia, lid retraction).
- Monitor thyroid function (T3, T4, TSH, antithyroid antibodies) every 4–6 months.
Key Terms & Definitions
- Thyroid Eye Disease (TED) — Inflammatory orbitopathy linked to Graves disease.
- Proptosis — Abnormal protrusion of the eye.
- NO SPECS — Grading system for TED features.
- Clinical Activity Score (CAS) — Standardized score for disease activity.
- Barrett’s Muscle Index — Imaging metric for predicting optic neuropathy in TED.
Action Items / Next Steps
- Review clinical signs and grading systems for TED.
- Practice clinical documentation and assessment for TED, including eyelid and motility measurements.
- For follow-up: monitor thyroid levels and disease activity score every 4–6 months.
- Prepare for next lecture on medical management of TED.