Mnemonic: "NO SPECS":[7]
Class 0: No signs or symptoms
Class 1: Only signs (limited to upper lid retraction and stare, with or without lid lag)
Class 2: Soft tissue involvement (oedema of conjunctivae and lids, conjunctival injection, etc.)
Class 3: Proptosis
Class 4: Extraocular muscle involvement (usually with diplopia)
Class 5: Corneal involvement (primarily due to lagophthalmos)
Class 6: Sight loss (due to optic nerve involvement)
Class 0: No signs or symptoms
Class 1: Only signs (limited to upper lid retraction and stare, with or without lid lag)
Class 2: Soft tissue involvement (oedema of conjunctivae and lids, conjunctival injection, etc.)
Class 3: Proptosis
Class 4: Extraocular muscle involvement (usually with diplopia)
Class 5: Corneal involvement (primarily due to lagophthalmos)
Class 6: Sight loss (due to optic nerve involvement)