Structural brain alterations in primary open angle glaucoma: a 3T MRI study

Abstract

Glaucoma is not only an eye disease but is also associated with degeneration of brain structures. We now investigated the pattern of visual and non-visual brain structural changes in 25 primary open angle glaucoma (POAG) patients and 25 age-gender-matched normal controls using T1-weighted imaging. MRI images were subjected to volume-based analysis (VBA) and surface-based analysis (SBA) in the whole brain as well as ROI-based analysis of the lateral geniculate nucleus (LGN), visual cortex (V1/2), amygdala and hippocampus. While VBA showed no significant differences in the gray matter volumes of patients, SBA revealed significantly reduced cortical thickness in the right frontal pole and ROI-based analysis volume shrinkage in LGN bilaterally, right V1 and left amygdala. Structural abnormalities were correlated with clinical parameters in a subset of the patients revealing that the left LGN volume was negatively correlated with bilateral cup-to-disk ratio (CDR), the right LGN volume was positively correlated with the mean deviation of the right visual hemifield, and the right V1 cortical thickness was negatively correlated with the right CDR in glaucoma. These results demonstrate that POAG affects both vision-related structures and non-visual cortical regions. Moreover, alterations of the brain visual structures reflect the clinical severity of glaucoma.

Management of Glaucoma As a Neurodegenerative Disease

“…Studies have shown that the glaucoma-associated neurodegeneration process is not limited to the optic nerve, but involves the whole visual pathway extending to the lateral geniculate nucleus and visual cortex [7][8][9], as demonstrated by MRI imaging showing a reduction in height and volume of the LGN in subjects with POAG [10] and NTG [11]. Similarly, fMRI studies have confirmed alterations in the visual cortex that correlate with the visual field changes observed in glaucoma [10,12].…”

Glaucoma: the retina and beyond

“…Structural MRI studies have revealed a significantly shorter optic chasm height and reduced optic nerve diameter in glaucoma patients versus normal controls [203]. Neurodegenerative changes in the LGN, as evidenced by reduction in LGN height and volume, is also reported in POAG patients using voxel-based morphometry and diffusion tensor imaging, with some evidence emerging to suggest that the extent of atrophy may correlate with disease severity [183]. A reduced LGN volume is also reported in patients with NTG versus age-matched controls, which may indicate a shared pathology in the brain [203].…”

“…In addition to LGN atrophy, a reduction in volume of the optic radiations and primary visual cortex is documented in patients with POAG [183]. There is some evidence to suggest that a loss of grey matter density occurs in the calcarine sulcus and primary visual cortex in response to prolonged sensory deprivation (AMD and glaucoma patients versus age-matched controls) [14].…”

Diffuse brain damage in normal tension glaucoma

“…In fact, NTG cases represent about 25–32% of overall POAG cases, both in the Beaver Dam study in Wisconsin, USA [Klein et al, ] and in the Egna Neumarkt study in Alto Adige, Italy [Bonomi et al, ] whereas NTG prevalence is three to four times higher than HTG in Japan [Shiose et al, ]. In POAG with raised IOP, we and others have previously demonstrated through multimodal brain MRI widespread damage of diffusion tensor imaging (DTI)‐derived anatomical connectivity (AC), gray matter (GM) atrophy and/or altered resting state functional connectivity (FC) that can go beyond the visual system, even since the early disease stage [Dai et al, ; Frezzotti et al, ; Jiang et al, ; Wang et al, ; Zikou et al, ].…”