Glaucoma screening: The importance of combining test data

The objective of this study was to evaluate the effectiveness of screening tests for primary open angle glaucoma, both singly and in combination, using a decision analysis approach. A range of screening tests were carried out on 145 nonglaucomatous patients and 67 cases of previously undiagnosed glaucoma. Receiver operator characteristic curves were constructed for single test data to show the trade-off between sensitivity and specificity for varying cut-off criteria. The best discriminators of glaucoma were, in rank order: (1) a multiple stimulus static visual field screening test, (2) optic disc cupping, and (3) intraocular pressure. Decision curves were also constructed for various combinations of screening tests, where the inclusion of the tests were based on discriminant analyses. Sensitivities and specificities of more than 0.90 were obtained when visual field screening, optic disc cupping, and intraocular pressure were combined. Data from other tests when combined with these three variables failed to provide a significant improvement in discrimination.