Case‐finding for angle closure: the diagnostic value of simple tests for estimating limbal and central anterior chamber depth

Abstract

PurposeTo evaluate the diagnostic accuracy of limbal and central anterior chamber depth measurement for detecting gonioscopically narrow anterior chamber angles (ACAs).MethodsA total of 78 subjects with narrow or open ACAs underwent an assessment of anterior chamber depth at the temporal limbus by estimating depth as a percentage of peripheral corneal thickness (van Herick test) by one examiner and just‐touching‐slit‐length measurements of the central anterior chamber depth (Smith's test) by a second examiner. Diagnostic performance was compared with (a) a gonioscopy reference standard, performed by a third examiner using the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) definition of primary angle closure and (b) a classification based on clinical opinion of occludability. All examiners were masked regarding each subject's clinical status and other test results. Sensitivity, specificity, and partial area under the receiver operating characteristic curve (AUROC) were generated.ResultsThe van Herick grading cutoff of 25% or less and ISGEO gonioscopic classification achieved 80% (95% CI 65–89) sensitivity and 92% specificity (95% CI 80–97) for narrow angle detection, with specificity reaching 97% (95% CI 87–100) for a cutoff of less than or equal to 15%. Notably, with a gonioscopic classification based on clinical opinion of occludability, van Herick (≤25%) together with Smith's test (≤2.50 mm) detected 100% of narrow angle subjects.ConclusionsThe van Herick test provides good discrimination between narrow and open angles both alone, and in combination with the measurement of central anterior chamber depth. These tests show good potential for identifying individuals who may benefit from further gonioscopic assessment in a case‐finding or screening setting.