Arterial spin labeling fMRI measurements of decreased blood flow in primary visual cortex correlates with decreased visual function in human glaucoma

Abstract

Purpose Altered metabolic activity has been identified as a potential contributing factor to the neurodegeneration associated with primary open angle glaucoma (POAG). Consequently, we sought to determine whether there is a relationship between the loss of visual function in human glaucoma and resting blood perfusion within primary visual cortex (V1). Methods Arterial spin labeling (ASL) functional magnetic resonance imaging (fMRI) was conducted in ten participants with POAG. Resting cerebral blood flow (CBF) was measured from dorsal and ventral V1. Behavioral measurements of visual function were obtained using standard automated perimetry (SAP), short-wavelength automated perimetry (SWAP), and frequency-doubling technology perimetry (FDT). Measurements of CBF were compared to differences in visual function for the superior and inferior hemifield. Results Differences in CBF between ventral and dorsal V1 were correlated with differences in visual function for the superior versus inferior visual field. A statistical bootstrapping analysis indicated that the observed correlations between fMRI responses and measurements of visual function for SAP (r = 0.49), SWAP (r = 0.63), and FDT (r = 0.43) were statistically significant (all p < 0.05). Conclusions Resting blood perfusion in human V1 is correlated with the loss of visual function in POAG. Altered CBF may be a contributing factor to glaucomatous optic neuropathy, or it may be an indication of post-retinal glaucomatous neurodegeneration caused by damage to the retinal ganglion cells.

Retinotopic Changes in the Gray Matter Volume and Cerebral Blood Flow in the Primary Visual Cortex of Patients With Primary Open-Angle Glaucoma

“…19 A recent study reported reduction in the resting CBF in the primary visual cortex and its correlation with the loss of visual function in patients with POAG. 44 These findings are evidence of widespread involvement of the cerebrovascular system in glaucoma. It has, however, remained unclear whether and how cerebral vascular changes contribute to the brain neurodegeneration in glaucoma.…”

Primary angle-closure glaucomas disturb regional spontaneous brain activity in the visual pathway: an fMRI study

“…Duncan et al demonstrated that POAG had decreased cerebral blood flow in the visual cortex,17 suggesting that regional metabolism and blood flow contribute to the phenomenon. Li et al also found significantly decreased ALFF/fALFF values in the visual cortices in POAG 12.…”

Morphologic changes in the anterior and posterior subregions of V1 and V2 and the V5/MT+ in patients with primary open-angle glaucoma

“…Several recent VBM studies have demonstrated a significant reduction in either GM volume (Chen et al, 2013a;Zikou et al, 2012) or density (Boucard et al, 2009;Li et al, 2012) in the V1 and V2 areas. Furthermore, lesions on the visual cortex were also shown in functional MRI (Duncan et al, 2007;Qing et al, 2010), resting blood perfusion (Duncan et al, 2012), experimental animal models (Lam et al, 2009;Yucel et al, 2003) and postmortem histological examinations (Gupta et al, 2006). However, the majority of these studies have mainly focused on GM atrophy or functional defects in the advanced or severe stages of disease, rather than on the progressive changes that occur in the visual cortex.…”