Search for an optimal combination of structural and functional parameters for the diagnosis of glaucoma - Multivariate analysis of confocal scanning laser tomograph, blue-on-yellow visual field and retinal nerve fiber layer data

Background: The purpose of this study was to evaluate which of the structur al and functional parameters - the Heidelberg Retina Tomograph (HRT), white -on-white (W/W) and blue-on-yellow (B/Y) visual fields and semiquantitative retinal nerve fiber layer (RNFL) scoring parameters - can give the best se paration between non-glaucomatous and glaucomatous eyes. Methods: Fifty-five subjects were included in this study: 32 nonglaucomatou s subjects with mean age of 54 years, and 23 patients with ocular hypertens ion or glaucoma and mean age of 59 years. The HRT with software 1.11, the H umphrey 30-2 W/W and lens coloration-corrected BN visual fields, and semiqu antitative RNFL scores were utilized. Stepwise logistic regression analysis was used in finding, from a given set of parameters, a best discriminating parsimonious subset to a logistic model, the discriminatory performance of which was evaluated by the area under the ROC curve. Results: When all the structural and functional variables were considered, the RNFL total overall score gave the best separation between glaucomatous and non-glaucomatous eyes (ROC area 0.98). Without the RNFL scores and opti c disc size-dependent HRT parameters in the model, the cup shape measure wa s selected first (ROC area 0.88). In the second step the RNFL thickness was selected (ROC area 0.91), and in the third step the corrected B/Y mean dev iation (MD) was selected (ROC area 0.91). With only the HRT parameters in t he model, the cup/disc ratio was selected first (ROC area 0.88). However, w hen the groups were matched for optic disc size, all disc size-dependent HR T variables lost their discriminant power. Conclusion: Cup shape measure an d RNFL thickness, together with age- and lens coloration-corrected MD of th e B/Y perimetry provided good discrimination between healthy individuals an d patients with glaucoma.