Discriminating between early glaucoma and ocular hypertension: diagnostic accuracy of pattern electroretinogram and confocal scanning laser optic disc morphometry

Purpose To evaluate diagnostic accuracy of pattern electroretinogram (PERG) and confocal scanning laser optic disc morphometry in discriminating between early open-angle glaucoma (EOAG) and ocularhypertension (OHT). Methods Fifty-five randomly selected eyes of 55 patients, with a clinical diagnosis of EOAG (26; Humphrey mean deviation -7 dB) or OHT (29), were included in the study. Both groups were matched with respect to age, sex and family history. PERGs were recorded in response to sinusoidal gratings of optimal spatial frequency (1.7 cycles/deg), square-wave counterphased at 8 Hz. Response 2nd harmonic amplitude was measured. Confocal scanning laser morphometry was performed by Heidelberg Retina Tomograph (HRT; software 2.01). Among the various HRT parameters, disc area (DA), cuptodisc area ratio (CDA), rim area (RA) and cup shape measure (CSM) were selected for analysis. Data were analyzed by Analysis of Variance (ANOVA) and Receiver Operating Characteristics (ROC) curves. Correlation between functional and morphometric parameters was evaluated by multiple regression analysis. Results Mean PERG amplitude was smaller (p<O.Ol) in EOAG as compared to OHT eyes. Mean CDA and CSM were greater (p<O.Ol), and RA was smaller (p<O.Ol) in EOAG as compared to OHT eyes. The areas under the ROC curve were: PERG, 0.77; CDA, 0.69; RA, 0.71; CSM, 0.71 . Diagnostic accuracy did not differ significantly across measures. In the whole study population, PERG amplitudes were negatively correlated with CSM (r= -0.60, pCO.001). Conclusions: Functional and morphometric measures of early optic nerve damage display comparably good accuracy in discriminating between clinically defined EOAG and OHT eyes.