Abstract
Aim: Glaucoma is an optic neuropathy and glaucomateus damage proceeds from retinal ganglion cells to brain. A better understanding of retrobulbar damage will enable us to develop more efficient strategies and a more accurate understanding of glaucoma. We evaluated retrobulbar glaucomatous damage with favorable techniques for 1.5T MR imaging.Material and methods: Five glaucoma cases and one healthy subject are included. Diffusion tensor MR imaging and functional MR images were taken with 1.5T MR. Correlation of optic nerve and corpus geniculatum laterale diffusion tensor MR parameters with eye findings were statistically evaluated.Results: Optic nerve damage and cortical hypofunction were shown with diffusion tensor MR and functional MR imaging, respectively. Correlations of the apparent diffusion coefficient with mean deviation, pattern standard deviation, retinal nerve fiber layer thickness in distal optic nerve and fractional anisotropy with ganglion cell counting in proximal optic nerves and correlations of retinal nerve fiber layer thickness with axial diffusivities in both ipsilateral and contralateral corpus geniculatum laterales and with fractional anisotropy in ipsilateral corpus geniculatum laterale were statistically significant.Conclusion: The eye-brain connection in glaucoma can be evaluated with routine clinical instruments. Our results also revealed the eye-to-visual-pathway integrity of glaucomatous neurodegeneration, which must be verified in larger series.
Highlights
Glaucoma represents a group of neurodegenerative diseases characterized by structural damage to the optic nerve and the slow, progressive death of retinal ganglion cells (RGCs)
Glaucomatous asymmetries are defined according to the visual field (VF) Mean Deviation (MD), Pattern Standard Deviation (PSD) and OCT RNFL, GCC values; along with other clinical findings including best corrected visual acuities, intraocular pressure (IOP), optic nerve head cupping ratios (c/d)
While the VF, MD and PSD values of the patient were recorded for functional analysis, thereby hemodynamic activity assessment in the primary visual cortex was performed with Functional MRI (fMRI)
Summary
Glaucoma represents a group of neurodegenerative diseases characterized by structural damage to the optic nerve and the slow, progressive death of retinal ganglion cells (RGCs). Areas beyond the retina and optic nerve are taken into consideration in glaucoma as well. If we briefly recall the anatomy, it is as follows: the retina, optic nerve, optic chiasm, optic tracts, corpus geniculatum laterale (CGL) including lateral geniculate nuclei (LGN), optic radiations and striate cortex. Gupta and Yücel have provided primary histopathological evidences –including degenerative and/or neurochemical changes, which –are similar to those in neurodegenerative diseases, in the LGN [3] and changes in metabolic activity in both the LGN and visual cortex, in glaucoma patients [4]. Optic nerve and LGN shrinkage and cortical ribbon thickness reduction in the postmortem specimens of a glaucomatous patient have been reported by the same group [5]
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