209 L’étude en IRM dans les atteintes du champ visuel glaucomateux

Abstract

Glaucoma is associated with specific optic disk changes and corresponding visual field defects. A recent post-mortem study showed structural changes in the lateral geniculate nucleus (LGN) and visual cortex of a glaucoma patient. In our study, we examined the optic radiations as well as grey matter density in the visual cortex of a glaucoma patient by means of diffusion tensor imaging (DTI) and D T weighted images. One patient (male, 32y) diagnosed with congenital glaucoma that had previously been under multiple filtration surgery and eye drops treatment for more than 10 years was examined using a clinical 3T MR scanner. Seven healthy normal subjects constituted the control group. DTI was performed using 64 directions of motion-proving gradient with a b-factor of 1000 s/mm2. Fractional anisotropic (FA) maps were analyzed within the FSL package in order to detect potential differences in the optic radiations. The 3D T1-weighted images were acquired at 1mm isovoxel and grey matter density differences were evaluated using the Voxel Based Morphometry (VBM) option in SPM5. Compared to the control group, our analysis showed statistically decreased FA values in the optic radiations of the glaucoma patient. Grey matter density was as well statistically lower in the anterior part of primary visual cortex. These results suggest that structural changes in the optic radiations and visual cortex occur in glaucoma. To confirm these preliminary findings, this analysis will be carried out in cases of acquired glaucoma. This non-invasive technique enables the exploration of changes in cerebral structures such as tracts and grey matter related to visual function.