Glaucoma diagnostic capacity of optic nerve head haemoglobin measures compared with spectral domain OCT and HRT III confocal tomography.

Abstract

The computer program laguna onhe determines optic nerve head haemoglobin (ONH Hb) on retinal photographs based on detecting colour differences. This study compares the diagnostic capacity of Laguna ONhE with that of spectral domain optical coherence tomography (OCT) and confocal tomography (HRT III). In a prospective, observational, cross-sectional study, glaucomatous (n=66) and healthy (n=52) eyes were examined by Spectralis OCT, HRT III and Laguna ONhE. The following Laguna ONhE variables were determined: ONH Hb across the vertical disc diameter (8&20Hb), estimated cup-disc ratio (C/D) and the glaucoma discriminant function (GDF), which combines the slope of Hb amount with the mean in 8&20Hb. The three diagnostic methods were compared by calculating areas under ROC curves (AUCs). Correlations between variables were assessed through Spearman's rho coefficient. Areas under ROC curves (AUCs) were 0.785 (95% CI: 0.700-0.863) for GDF, 0.807 (95% CI: 0.730-0.883) for OCT retinal nerve fibre layer thickness (OCT-RNFL) and 0.714 (95% CI: 0.618-0.810) and 0.721 (95% CI: 0.628-0.815) for the HRT III variable GPS (glaucoma probability score) and vertical C/D ratio, respectively. Glaucoma discriminant function (GDF) was correlated with OCT-RNFL (0.587, p 0.001; 0.507, p 0.045; and -0.119, p 0.713 for mild, moderate and advanced glaucoma, respectively), mostly so with inferior OCT-RNFL (0.622; p<0.001). Glaucoma discriminant function (GDF)-HRT III correlations were lower (rim area 0.471, p<0.0001; rim/disc area 0.426, p<0.0001; vertical C/D -0.413, p<0.0001; GPS -0.408, p<0.0001; rim volume 0.341, p<0.0001). Similar diagnostic power was observed for Laguna ONhE, Spectralis OCT and HRT III.