The clinical activity score (CAS) is used to guide immunosuppressive treatment in thyroid eye disease. A CAS score of ≥3/7 indicates:

• A Inactive disease requiring observation only
• B Sight-threatening disease requiring emergency decompression
• C Chronic stable proptosis requiring rehabilitative surgery
• D Active disease likely to respond to immunosuppression ✓

Explanation

The Clinical Activity Score (CAS) assesses seven inflammatory signs: spontaneous orbital pain, pain on gaze, lid erythema, conjunctival injection, chemosis, swollen caruncle/plica, and lid edema. A score ≥3/7 indicates clinically active disease with ongoing inflammation that is likely to respond to immunosuppressive therapy (IV steroids, orbital radiotherapy, or teprotumumab). Inactive disease (CAS 0–2) is managed with lubricants and rehabilitative surgery if deformity persists.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.