new criteria to assess the risk of acute angle closure

purpose: to compare anterior segment and ocular biometric parameters of unaffected fellow eyes of patients with a previous attack of acute angle closure (aac), primary angle closure suspect (pacs) eyes, and normal eyes; and to assess the risk of developing aac in pacs. methods: in this prospective comparative observational case series, 16 unaffected fellow eyes of patients with a previous attack of aac (group i), 40 pacs eyes (group ii) and 32 normal eyes (group iii) were evaluated. pentacam and a-scan echography were performed in all cases. anterior chamber angle (aca), anterior chamber volume (acv), anterior chamber depth (acd), central corneal thickness (cct), keratometry (kr), lens thickness (lt) and axial length (al) were measured in all eyes as main outcome measures. results: age, cct and lt were comparable among the study groups (all p values>0.05). mean aca was 24.8°, 22.9° and 35.4° in groups i, ii, and iii respectively (p<0.001). corresponding values for acv were 72, 76 and 172 µl, respectively (p<0.001). central acd measured from the endothelium was 1.80, 1.91, and 3.09 mm in groups i, ii, and iii respectively (p<0.001). using receiver operating characteristic (roc) curves, acv≤100 µl was associated with a high risk of aac with sensitivity of 91.7% [95% confidence interval (ci):70 to 99] and specificity of 100% (95% ci: 89 to 100). corresponding values for aca≤25° were 75% (95% ci: 51 to 90) and 93.3% (95% ci: 79 to 98); and for acd≤2.1 mm were 86.7% (95% ci: 62 to 96) and 100% (95% ci: 89 to 100) respectively. if two of these three criteria (acv≤100 µl, aca≤25° and acd≤2.1 mm) are present, the eye can be considered at high risk for an attack of aac with sensitivity of 93.3% (95% ci: 70 to 99) and specificity of 100% (95% ci: 89 to 100). conclusion: eyes with acv≤100 µl, aca≤25° and acd≤2.1 mm should be considered at high risk for developing acute angle closure and can be considered for prophylactic laser peripheral iridotomy (lpi).