Decreased activation of the lateral geniculate nucleus in a patient with anisometropic amblyopia demonstrated by functional magnetic resonance imaging

Abstract

Although postmortem morphological changes in the lateral geniculate nucleus (LGN) have been reported in human amblyopia, LGN function during monocular viewing by amblyopic eyes has not been documented in humans. We used functional magnetic resonance imaging (fMRI) to study monocular visual activation of the LGN in a patient with anisometropic amblyopia. Four normal subjects, a patient with optic neuritis and a patient with anisometropic amblyopia were studied with fMRI at 1.5 T during monocular checkerboard stimulation. Activated areas in the LGN and visual cortex were identified after data processing (motion correction and spatial normalization) with SPM99. In the 4 normal subjects, comparable activation of the LGN and visual cortex was obtained by stimulation of either the right or left eye. In the patient with unilateral optic neuritis, activation of the LGN and visual cortex was markedly decreased when the affected eye was stimulated. Similarly, decreased activation of the LGN as well as the visual cortex by the affected eye was demonstrated in the patient with anisometropic amblyopia. Our preliminary results suggest that activation of the LGN is diminished during monocular viewing by affected eyes in anisometropic amblyopia. fMRI appears to be a feasible method to study LGN activity in human amblyopia.