Optic Nerve Head Hemoglobin Levels in Glaucoma: A Structural and Functional Correlation Study

Abstract

Purpose. To investigate structural and functional correlations in glaucoma patients using optic nerve head hemoglobin (ONH Hb) measurements as determined by automated colorimetric analysis of conventional retinography. Methods. We prospectively enrolled healthy participants and glaucomatous patients with a wide range of disease stages. All participants underwent visual field (VF) testing (standard automated perimetry, SAP), color fundus imaging (mydriatic retinography), and peripapillary retinal nerve fiber layer (pRNFL) assessment through spectral-domain optical coherence tomography (SD-OCT). Software Laguna ONhE was used to estimate the amount of ONH Hb and to determine the glaucoma discriminant function (GDF) index. Scatter plots were constructed, and regression analysis was used to investigate the correlations between GDF, average pRNFL thickness, and VF mean deviation (VFMD) index values. A secondary analysis was performed to compare each parameter between three different glaucoma groups divided according to VFMD values (mild, >−6 dB; moderate, −6 to −12 dB; and advanced, <−12 dB). Results. One hundred ninety-six eyes from 123 participants (69 with glaucoma and 54 controls) were enrolled. Overall, all parameters evaluated differed significantly between glaucomatous and control eyes ( p ≤ 0.001 ). The comparison of each parameter according to groups of disease stages revealed significant differences between controls and each of the glaucomatous groups ( p < 0.001 ). More pronounced changes in GDF values were observed in early disease stages. We found significant nonlinear correlations between GDF and VFMD values (R2 = 0.295, p < 0.001 ) and between pRNFL thickness and VFMD (R2 = 0.598, p < 0.001 ). A linear correlation was found between GDF and pRNFL thickness values (R2 = 0.195, p < 0.001 ). Conclusion. Our results showed significant associations between ONH Hb values and both structural and functional damage in glaucoma obtained by SD-OCT and SAP, respectively. The nonlinear correlation we found and the GDF behavior along different disease stages suggest that ONH Hb levels’ reduction may precede visual function changes in early glaucoma stages.

Identification of Glaucoma in Diabetics Using the Laguna-ONhE Colourimetric Method and OCT Spectralis

“…However, in the different studies, there is a notable difference in the results obtained between the Laguna-ONhE and OCT Spectralis RNFL indices. In chronic open-angle glaucoma, an equivalent diagnostic ability between the two indices has been found [ 27 ], while another study conducted in Brazil found, as in the present study, that the correlation between the two indices is poor [ 28 ]. These data may be related to racial or specific characteristics of normotensive glaucoma, as in the latter, a higher diagnostic ability of BMO-MRW vs. RNFL has been reported [ 14 ].…”

Automated Optic Nerve Head Hemoglobin Measurements versus General Ophthalmologists Evaluation to Differentiate Glaucomatous from Large Physiological Cupping: A Diagnostic Performance Comparative Study

“…Considering structure-functional correlations in glaucoma, our group has previously shown a significant linear correlation between hemoglobin levels and OCT parameters and a significant nonlinear correlation between GDF and VF values. 23 Analyzing the GDF pattern in different glaucoma stages, we documented that the GDF values decay may precede VF changes overtime. Other studies also showed good agreement between ONH Hb and both OCT and VF, based on Octopus and Easyfield perimeters.…”

“… 22 Our group demonstrated significant associations between ONH Hb values and both structural and functional damage in glaucoma. 23 …”

Current status and practical considerations of artificial intelligence use in screening and diagnosing retinal diseases: Vision Academy retinal expert consensus

“…It can detect DR lesions, including microaneurysms and minor hemorrhages (specificity of 71.4%) [95]. It can also evaluate biological aging [96] and hemoglobin on optic disc photographs [97] RetinAI transparency should be a concern in the application of AI-enabled technologies.…”