Dutch Ophthalmologists Association Meeting 2011

This study aims to find if there is any structure and function correlation between the visual pathway structures volume and the mean deviation (MD) of visual field in primary open-angle glaucoma (POAG). Seventeen subjects with varying stage of POAG voluntarily participated in the study. The staging were based on the Hodapp-Parrish system. Only POAG patients with a minimum of three years of established diagnosis were included. The visual fields were taken with automated static perimetry to obtain the mean deviation (MD) of the visual field sensitivity. Magnetic resonance (MR) brain diffusion tensor imaging (DTI) and anatomical T1-weighted (T1W) imaging of all subjects were acquired on a 3T MR scanner. T1W images were processed to allow for volume measurement. Diffusion-weighted (DW) image processing were done to obtain the FA maps. Both T1W- and DW-derived images were eventually subjected to voxel-based morphometry (VBM) to allow for localising spatially any statistically significant findings. Regions-of-interest (ROI) based analyses were also done to allow for quantitative analyses. VBM and ROI-based analyses yielded that the pregeniculate structures and the MD were correlated (R=0.65, p<0.01). In summary, there is a positive correlation between the MD and the volume of the pregeniculate structures. They may already be involved in the early stage of POAG.

Dutch Ophthalmologists Association Meeting 2009

Optic tract diameter and retinal nerve fiber layer thickness show a trend towards decreasing with glaucoma disease stage.

Dutch Ophthalmic Physics Day 2009

Visual cortex in long-standing retinal visual field defects

Dutch Ophthalmologists Association Meeting 2008

Retinal lesions caused by eye diseases such as glaucoma and age-related macular degeneration can, over time, eliminate stimulation of parts of the visual cortex. This could lead to degeneration of inactive cortical neuronal tissue, but this has not been established in humans. Here, we used magnetic resonance imaging to assess the effects of prolonged sensory deprivation in human visual cortex. High-resolution anatomical magnetic resonance images were obtained in subjects with foveal (age-related macular degeneration) and peripheral (glaucoma) retinal lesions as well as age-matched controls. Comparison of grey matter between patient and control groups revealed density reductions in the approximate retinal lesion projection zones in visual cortex. This indicates that long-term cortical deprivation, due to retinal lesions acquired later in life, is associated with retinotopic-specific neuronal degeneration of visual cortex. Such degeneration could interfere with therapeutic strategies such as the future application of artificial retinal implants to overcome lesion-induced visual impairment.

European Conference on Visual Perception 2008

Studies have indicated the presence of volumetric changes both in glial cells and the extracellular space during neuronal activity (Sykova and Chvatal, 2000 Neurochemistry International 36 397 - 409; Dietzel et al, 1980 Experimental Brain Research 40 432 - 439). In this study, we examined whether such volume changes at the cellular level are translated into changes that can be observed at the scale of the cerebral cortex. Two subsequent T1-weighted anatomical MRI scans were obtained in eight subjects. During the first scan, the subject was viewing a 6.5 min movie of natural scenery; during the second scan, the subject had his eyes closed (rest). The acquired cortical scans were subsequently analyzed using voxel-based morphometry. Comparing cortical anatomy during viewing vs rest revealed no detectable volumetric changes in the grey matter of visual cortex. However, such volumetric changes were observed in the anterior cingulate cortex and bilaterally in the insulas. These results suggest that acute volumetric changes at the cellular level related to neuronal activity can result in macroscopically detectable changes in cortical anatomy.