Example: One hundred persons with primary angle closure glaucoma (PACG, diagnosed by 'gold standard': gonioscopy) are examined by van Herick test. Seventy-five of them had narrow peripheral anterior chamber depth [Table 3]. The sensitivity of the peripheral anterior chamber depth examination to PACG is therefore - Table 3 Shows example for the calculation of sensitivity and specificity New test Gold standard Positive Negative Test +ve 75 15 Test -ve 25 85 Total 100 100 Sensitivity: Specificity: 75/100 85/100