A 40-year-old woman presents with bilateral proptosis, lid lag, and chemosis. Her TSH is suppressed. On Hertel exophthalmometry, proptosis measures 25 mm bilaterally. Corneal exposure keratopathy is developing. Which feature would indicate the need for urgent orbital decompression rather than conservative management?

• A Clinical activity score (CAS) of 3/7
• B Diplopia in primary gaze controllable with prisms
• C Mild conjunctival injection and chemosis
• D Compressive optic neuropathy with relative afferent pupillary defect and reduced colour vision ✓

Explanation

In thyroid eye disease (Graves' orbitopathy), compressive optic neuropathy (CON) is the most vision-threatening complication and is an absolute indication for urgent intervention—either high-dose IV methylprednisolone or emergency surgical decompression. CON is detected by RAPD, reduced colour vision (especially red desaturation), and visual field defects. CAS of 3/7 is only moderate activity; diplopia with prism correction and mild conjunctival signs are indications for immunosuppression but not emergency decompression.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.