The Clinical Activity Score (CAS) for Graves' ophthalmopathy is based on 4 of the 5 classic signs of inflammation (calor, rubor, dolor, tumor, etc.). It is intended to distinguish between patients with active ophthalmopathy who are likely to respond to immunosuppressive therapy and patients with fibrotic end stage disease who are not likely to respond to immunosuppression. Disease activity and not disease duration is concluded to be the prime determinant of therapeutic outcome.
Sign of Inflammation
Item
Finding
pain
1
painful, oppressive feeling on or behind the globe, during the last 4 weeks
2
pain on attempted up, side or down gaze, during the last 4 weeks
redness
3
redness of the eyelid(s)
4
diffuse redness of the conjunctiva, covering at least one quadrant
swelling
5
swelling of the eyelid(s)
6
chemosis
7
swollen caruncle
8
increased proptosis of >= 2 mm during a period of 1-3 months
impaired function
9
decrease of eye movements in any direction >= 5° during a period of 1-3 months
10
decrease of visual acuity of >= 1 line(s) on the Snellen chart (using a pinhole) during a period of 1-3 months
where:
• caruncle = lacrimal caruncle
clinical activity score (CAS) =
= SUM (number of items present)
Interpretation:
• minimal score: 0
• maximum score: 10
• A CAS score >= 4 predicted response to immunosuppressive therapy (oral prednisone or retrobulbar irradiation) with: specificity of 86%, sensitivity of 55%, positive predictive value of 80%, and negative predictive value of 64%.
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