Structure-Function correlation using optical coherence tomography in normal subjects, preperimetric and manifest primary open-angle glaucoma.

Abstract

Background Primary open-angle glaucoma is a chronic optic neuropathy. Diagnosis and monitoring require several functional and structural investigations. Structure-function correlation is a capital step of the management. The aim of this study was to assess the correlation between tomographic and functional parameters in normal, preperimetric and manifest glaucoma cases. Methods This retrospective analytical study included 275 eyes (152 cases). Participants were divided into 3 groups: 33 normal subjects, 32 patients with preperimetric glaucoma and 87 patients with manifest glaucoma. All subjects underwent a complete ophthalmologic examination, a visual field and spectral-domain optical coherence tomography (SD-OCT). Results Correlation between functional and tomographic parameters was non-significant in the group of normal or preperimetric glaucoma subjects. Regarding manifest glaucoma group, mean deviation (MD) was significantly correlated with all tomographic parameters (p<0.001). The loss variance (LV) was significantly correlated with tomographic assessment of Retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). The regression studies of (MD - RNFL /GCC) and (LV - GCC) had significant results with nonlinear models (p <0.001). Linear and polynomial models were used to correlate LV and average RNFL (p=0,275). Conclusions No structure-function correlation was observed at the preperimetric stage. However, MD correlated with tomographic parameters more than LV in manifest glaucoma group. Curvilinear function might be the appropriate model for the structure-function relationship assessment. Key words Primary open-angle glaucoma; Retinal ganglion cells; Retinal nerve fiber; Optical coherence tomography; Correlation.