Functional MRI Signal Changes in Primary Visual Cortex Corresponding to the Central Normal Visual Field of Patients with Primary Open-Angle Glaucoma

Abstract

Glaucomatous neuropathy from POAG may lead to decreased cortical activity in the primary visual cortex, which corresponds to the central normal visual field. The resultant cortical depression is not related to interocular differences in results of polarimetry, OCT, and ophthalmoscopy, but is negatively correlated with PSD of visual field analysis.

Functional MRI Characteristics in Visual Cortex (BA 17, 18 and 19) Corresponding to the Visual Field of Normal, Glaucoma Suspect (GS) and Primary Open Angle Glaucoma (POAG) Patients

“…The differences are however not significant which could probably be due to insufficient number of participants for comparisons (Qing et al 2010). In a previous study (Qing et al 2010), it has been determined that the activated voxels (2086 ± 1063) in visual cortex obtained from participants that visualized the stimuli using their glaucomatous eye did not differ (p = 0.428) from activated voxels (1813 ± 1239) obtained from participants with normal vision. Further investigation indicated that all glaucomatous participants visualizing using their glaucomatous eye evoked a smaller BOLD response as compared to visualizing through their fellow eye.…”

“…The decrease of BOLD response evoked by the glaucomatous eyes may be due either to a flow-on effect of early perceptual loss or to cortical abnormalities. (Qing et al 2010). Thus, the POAG patients may face a complexity in their daily visual tasks.…”

“…Glaucomatous neuropathy involves the whole visual pathway and neural activity relies on regulation of blood vessels (Qing et al 2010). Therefore, the decreasing trend in the activated voxels in POAG patients can be assumed to be resulted from BOLD signal which was interrupted by cerebral vascular activity in POAG.…”

“…Therefore, the decreasing trend in the activated voxels in POAG patients can be assumed to be resulted from BOLD signal which was interrupted by cerebral vascular activity in POAG. Changes in cerebral blood flow were directly controlled by neurons and neuronal atrophy whereby postretinal visual pathway in POAG patients may affect the neuron-vascular coupling which would lead to the reduction of BOLD signal (Qing et al 2010) and consequently less fMRI activation. Other researchers also reported that the neuronal degeneration and activity of V1 and LGN greatly reduced the metabolic activity within V1 in glaucoma patients.…”

“…(Boucard et al 2009). However, changes in activity in visual cortex region can only be found in limited number of glaucoma studies conducted using fMRI Qing et al 2010).…”