Optic disc parameters in manifest and suspected glaucoma

Structure and function measurements are important in glaucoma management. Digital fundus photography has become a standard procedure and the Heidelberg Retina Tomograph (HRT), commonly used by glaucoma specialists, provides a glaucoma probability score (GPS). The visual field index (VFI) is a novel statistic, aiming to facilitate follow-up of glaucoma patients. The aim of this study was to compare the results from the digital analysis of fundus photographs with HRT measurements including GPS and VFI in patients with ocular hypertension, suspect glaucoma or glaucoma, and if possible define an optic disc index, useful in glaucoma diagnosis. Fifty-eight consecutive patients from a glaucoma service were included. Optic disc parameters (disc and cup areas) were measured on digital fundus photographs, using a semi-automatic method, and compared with the GPS from the HRT and the VFI from standard automated perimetry. A significant relationship was observed between the GPS group classification (normal, borderline, or abnormal) and VFI classification (normal or abnormal), both when the GPS borderline group was regarded as normal (P = 0.0038 Fisher test) and as abnormal (P=0.0179, kappa = 0.33). No significant relationship was observed between VFI and optic disc parameters. The threedimensional information in the GPS appears to be more related to visual function, as measured by VFI, than the planimetric measures of the optic disc.