Diagnostic accuracy of the non-compliance of the ISNT rule in glaucoma: Systematic review and meta-analysis

Purpose This systematic review and meta-analysis evaluated the pooled diagnostic accuracy of the ISNT rule non-compliance in detecting glaucoma, considering diverse technique approaches. Methods A comprehensive literature search was conducted. The primary outcome was the pooled diagnostic accuracy of ISNT rule non-compliance, quantified through various tools. Secondary outcomes included subgroup comparisons based on approach type (neuroretinal rim [NRR] width versus recently described approaches), analysis method (original versus modified), measuring tool, anatomical site evaluated, ISNT rule definition, and the continent where the study was conducted. Risk of bias was assessed using the modified Quality Assessment of Diagnostic Accuracy Studies 2 tool. Results A total of twenty-two results derived from six distinct measurement approaches across eighteen studies were included. The pooled diagnostic accuracy estimates were for sensitivity, 0.83 (confidence interval [CI]:0.77–0.88); specificity, 0.49 (CI:0.35–0.63); positive likelihood ratio, 1.60 (CI:1.30–2.15); negative likelihood ratio, 0.37 (CI:0.27–0.49); and diagnostic odds ratio, 4.55 (CI:2.76–7.50). No statistically significant differences were found between subgroup comparisons, except for the specificity of the original method (0.72 [CI:0.67–0.77]), sensitivity of the modified method (0.85 [CI:0.78–0.90]), and sensitivity of the NRR (0.86 [CI:0.79–0.91]). Conclusions The ISNT rule presented a low specificity but a high sensitivity for glaucoma diagnosis and may be a useful tool for screening.