[Study of functional magnetic resonance imaging in strabismic and anisometropic amblyopic patients]

To elucidate the difference in the pathogenesis between strabismic amblyopia and anisometropic amblyopia.

Using an EPI gradient echo sequence in 1.5 T MRI and visual electrophysiological system, the pattern visual evoked potentials and calcarine activation by monocular viewing of check-board pattern with reversal were examined in 18 strabismic amblyopes and 15 anisometropic amblyopes. The calcarine activation in terms of binocular voxels index and dependence on the spatial frequency of the stimuli were compared. The correlation between PVEP P(100) latency and activation intensity was also analyzed.

The binocular voxels index was lower in the strabismic amblyope than that in the anisometropic amblyope. The calcarine activation from amblyopic eyes in strabismic amblyopes was more suppressed at higher spatial frequencies (1, 2 c/d); while that from amblyopic eyes in anisometropic amblyopes was more suppressed at all spatial frequencies (0.25, 0.5, 1 and 2 c/d). Inverse correlations existed between PVEP P(100) latency and activation intensity in two types amblyopia (P < 0.05).

The binocular interaction is not equal in these two different types of amblyopia. Meanwhile, the amblyopia-related deficits in the low and high-spatial-frequency pathway of visual system are not similar between these two different types of amblyopia.