斜视性和屈光参差性弱视患者的功能磁共振成像研究

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

目的比较斜视性弱视和屈光参差性弱视的机制的异同。方法采用视觉电生理诊断系统及1.5T 磁共振成像仪分别记录18例斜视性弱视和15例屈光参差性弱视患者的视觉诱发电位与血氧水平依赖功能磁共振成像信号。比较斜视性弱视和屈光参差性弱视患者的双眼像素指数及不同刺激条件下双眼大脑皮层神经元的平均活动水平,分析大脑皮层神经元的平均活动水平与 P_(100)波潜时的相关性。结果斜视性弱视患者的双眼像素指数较屈光参差性弱视患者明显减少(P<0.05)。选用任一空间频率(0.25、0.50、1.00、2.00c/d)刺激,屈光参差性弱视患者弱视眼驱使大脑皮层神经元平均活动水平均较对侧眼降低(P<0.05),斜视性弱视患者仅在高空间频率刺激时(1.00和2.00c/d),其弱视眼驱使大脑皮层神经元平均活动水平较对侧眼降低(P<0.01)。P_(100)波潜时与大脑皮层神经元平均活动水平呈负相关(P<0.05)。结论两种不同类型的弱视不仅双眼异常相互作用的程度不同,而且对视觉系统不同空间频率神经通路的损害亦不同。(中华眼科杂志,2006,42:873-877)

Objective To elucidate the difference in the pathogenesis between strabismic amblyopia and anisometropic amblyopia. Methods 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 P100 latency and activation intensity was also analyzed. Results 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 P100 latency and activation intensity in two types amblyopia（P 〈 0.05）. Conclusions 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. （Chin J Opbtbalmol, 2006,42：873-877）