·AIM:To evaluate the magnetic resonance imaging(MRI)measurement accuracy of axial length in silicone oil combined cataract eye.·METHODS:A prospective double-blind controlled study,respectively with MRI and A ultrasonometry,was conducted on silicone oil combined cataract eyes to measure the axial length,and the accuracy of the two methods.·RESULTS:Thirty-two eyes achieved correct measure-ment of axial length in the plane by MRI,the axial length of MRI was longer than that of A ultrasonometry by an average length of 0.16±0.20mm.·CONCLUSION:MRI measurement of axial length is more accurate and reliable than the A ultrasonometry measurement.·