Progressive thinning of visual cortex in primary open-angle glaucoma of varying severity.

Longhua Yu,Longhua Yu,Longhua Yu,Minglong Liang,Minglong Liang,Chao Dai,Chao Dai,Jian Wang,Jian Wang,Xuntao Yin,Xuntao Yin,Xuntao Yin,Xuntao Yin,Bing Xie,Bing Xie,Liqi Xie,Lu Zhao,Lu Zhao,Huiguang He

doi:10.1371/journal.pone.0121960

Abstract

The aim of this study was to investigate possible changes of cortical thickness in the visual cortex in primary open-angle glaucoma (POAG) of varying severity. Twenty normal controls (NC), 20 mild (MP) and 17 severe (SP) POAG patients were recruited and scanned using magnetic resonance imaging. Cortical thickness analyses with regions of interest (V1, V2, ventral V3, V4 and V5/MT+) were used to assess the cortical changes among the three groups. Furthermore, the associations of cortical thickness with retinal nerve fiber layer (RNFL) thickness and mean deviation of visual field were analyzed. Compared with the NC group, decreased cortical thickness was detected in the bilateral V5/MT+ areas in the MP group and the left V1, bilateral V2 and V5/MT+ areas in the SP group. Cortical thinning of the bilateral V2 areas was detected in the SP group compared with the MP group. In addition, cortical thinning of these visual areas was related to the ophthalmologic measurements. In conclusion, POAG patients exhibit cortical thinning in the bilateral V5/MT+ in the early stage of disease. The cortical degeneration in visual areas is discrepant with disease progressing and the dorsal pathway might be selectively damaged in POAG. Therefore, the cortical thinning of these visual areas may play a key role in the progression of POAG and can serve as a novel biomarker for accurately evaluating the severity of POAG.

Highlights

Primary open-angle glaucoma (POAG) is a progressive optic neuropathy and is characterized by irreversible retinal ganglion cells (RGCs) and optic nerve fibers loss [1], resulting in corresponding psychophysical abnormalities, such as visual field loss
Compared with the normal controls (NC) group, the severe patient (SP) group had significantly lower thickness in the left V1 area and bilateral V2 and V5/MT+ visual cortices, whereas the mild patients (MP) group only exhibited a significant reduction of cortical thickness in the V5/MT+ area
The most significant novel finding is that cortical thickness of the bilateral V5/MT+ areas decreases in the early stage of POAG

Summary

Introduction

Primary open-angle glaucoma (POAG) is a progressive optic neuropathy and is characterized by irreversible retinal ganglion cells (RGCs) and optic nerve fibers loss [1], resulting in corresponding psychophysical abnormalities, such as visual field loss. Progressive Thinning of Visual Cortex in POAG lateral geniculate nucleus (LGN) and even to the primary visual cortex (V1, striate cortex) [2,3,4,5,6] These studies indicated that glaucoma is a complex disorder in which the whole visual pathway may be involved. Several voxel-based morphometry (VBM) studies on magnetic resonance imaging (MRI) data have examined the disruption of brain gray matter (GM) in patients with POAG. These studies have demonstrated GM atrophy in the V1 and the second major visual area (V2) [7,8,9,10], indicating that signs of neurodegeneration in visual cortex encompass upstream parts of the higher visual areas (extrastriate cortex). Our recent whole-brain studies [8,15] failed to detect the GM changes in the early stage of POAG, which might be attributed to the small sample size

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