A MULTIVARIATE SENSORY MODEL IN GLAUCOMA DIAGNOSIS

PURPOSE. To evaluate whether the combination of two psychophysical and two electrophysiological procedures improves diagnostic validity comp ared with single procedures. METHODS. In a clinical study, 73 patients with glaucoma from the University Eye Hospital in Erlangen and 122 he althy control subjects from the university staff, ranging in age from 19 to 62 years, underwent measurement of temporal contrast sensitivity using a full-field flicker test, spatiotemporal contrast sensitivity, blue-on-yellow visual evoked potential (VEP), and a black-and-white, pattern-reversal electroretinogram. Diagnostic reference criteria incl uded applanation tonometry, optic disc morphometry, and automated peri metry. Sensitivity was determined univariately with a fixed specificit y of 80% and in a multivariate approach using logistic regression anal ysis. The classification rate was estimated using the leaving-one-out method. The correlation with intraocular pressure, visual field defect s, and optic nerve defects was determined. RESULTS. Contrast sensitivi ty measurements and the blue-on-yellow pattern-onset VEP showed compar able sensitivity (85%, 84%, and 85%) with 80% specificity, and a patte rn-reversal electroretinogram showed lower sensitivity (64%). The firs t three methods contributed independent information to a diagnostic sc ore. This score improved sensitivity to 94%, with a specificity of 89% . All procedures moderately correlated with the neuroretinal rim area of the optic disc (r = 0.32-0.46). The psychophysical tests showed a h igher correlation with visual field defects (r > 0.5) than the electro physiological tests (r < 0.3). CONCLUSIONS. The multivariate approach substantially increased the diagnostic validity compared with single p rocedures. This was probably because the diagnostic procedures under i nvestigation tested different aspects of visual function.