Detection of visual dysfunction in optic atrophy by functional magnetic resonance imaging during monocular visual stimulation.

PURPOSE

To evaluate functional magnetic resonance imaging as an objective method for detecting visual dysfunction in various ophthalmologic disorders involving the optic nerve and the chiasm.

METHODS

We performed functional magnetic resonance imaging during monocular visual stimulation on seven patients with visual field loss caused by lesions of the optic nerve and the chiasm and on three normal control subjects with no visual field loss. We correlated static threshold perimetry in the seven patients with the results of functional magnetic resonance imaging.

RESULTS

In the three normal control subjects, we found good intrasubject similarity in areas of bilateral occipital lobe activation between monocular stimulation of the right and left eyes. In the patients with unilateral optic neuropathy, including glaucoma, stimulation of the affected eye induced no activation of the primary visual cortex in the portion corresponding to the central visual field defects and reduced activity of the associated visual cortex. In the patients with chiasmal compression, monocular stimulation resulted in a marked asymmetry of activation in the primary visual cortex, which corresponded to the visual field abnormality.

CONCLUSIONS

Functional magnetic resonance imaging appears to be useful in confirming the clinical diagnosis of optic atrophy because it can objectively disclose visual field loss, even a small defect such as central scotoma.