Is Caruncular Oedema a Reliable Indicator in the Clinical Activity Score for Thyroid Eye Disease? An Analysis of Bias and Observer Variability

Caruncular oedema scoring within the CAS shows poor inter-observer reliability and vulnerability to cognitive and visual biases. Conjunctival and caruncular hyperaemia act as significant confounders, inflating disease activity scores and potentially shifting patients across the CAS threshold (> 3) that guides immunosuppressive treatment. Given these limitations, refinement or replacement of this criterion, through either objective imaging tools or alternative markers such as ocular hypertension, should be considered to improve the reproducibility and diagnostic value of the CAS in both ophthalmology and endocrinology practice.