Abstract
Purpose:
To investigate the impact of glaucoma on the cerebral blood flow (CBF) and grey matter density in patients with primary open angle glaucoma (POAG).
Methods:
POAG patients with obvious visual field loss (mean deviation, MD <-6dB) and best-corrected visual acuity of 20/40 or better were enrolled. Central 5°visual field in bilateral eyes must be reserved. History of cardiovascular diseases and other systemic disorders were excluded. Age and gender matched healthy subjects were enrolled as controls. T1-wighted anatomic images were acquired by a 3-Tesla MRI scanner (Trio; Siemens, Erlangen, Germany). Arterial spin labeling (ASL) MRI were then performed either at baseline or when receiving monocular reversing checkerboard stimulation (8Hz) that presented to the central reserved visual field. The eye with more severe visual field loss was chosen in glaucoma patients, while in controls the study eye was chosen randomly. Grey matter density and cerebral blood flow in the whole brain between groups were compared.
Results:
Comparing with controls, significant reduction of grey matter density was observed in the anterior part of calcarine sulcus in patients with POAG, which is considered to be the peripheral retina projection in the visual cortex. Whole brain ASL scanning revealed a decreased regional CBF in the same peripheral retinotopic region in occipital visual cortex of POAG patients at baseline. Monocular central visual field stimulation evoked significant increase of CBF in bilateral occipital poles in both controls and POAG patients. However, the activated voxels were much less in POAG patients than controls.
Conclusions:
POAG patients may suffer from retinotopic specific structure and cerebraovascular alterations in the occipital visual cortex. CBF insufficiency may precede the visual field loss and grey matter changes in glaucoma, which, therefore, may be used as a promising indicator for detecting early glaucomatous neurodegeneration. Glaucoma patients may benefit from neuroprotective and vascular regulatory strategies targeting at whole visual pathway.
Keywords: 613 neuro-ophthalmology: optic nerve