磁共振三维成像测量正视及近视眼球的形态

The three-dimensional MRI for estimating the shape of eyeball of emmetropia and myopia

目的了解磁共振三维成像测量的近视眼球形态学的特点为眼科的临床工作，特别是眼科手术提供参考。方法研究对象为40例（80只眼），包括正视眼、低度近视、中度近视及高度近视各10例（20只眼），凡有其他眼部器质性疾病或外伤、手术史者均被排除。所有研究对象均行磁共振三维成像序列检查，测量眼球矢状径、水平径、垂直径及眼球容积，并重建眼球三维图像、眼肌止点及视神经止点。结果低度近视、中度近视及高度近视眼的矢状径、水平径、垂直径均较正视眼者大，其中矢状径变化最显著；眼球容积均较正视眼大。重建的眼球三维图像、眼肌止点及视神经止点显示清晰。低度近视眼和中度近视眼未见明显的后葡萄肿形成，高度近视20只眼中15只眼见后葡萄肿形成。结论低度近视、中度近视及高度近视眼球各径线及眼球容积均较正视眼者大。磁共振三维成像序列可以清晰显示眼球形态、眼肌止点及视神经止点，对临床工作特别是眼科手术具有一定的应用价值。

Objective To investigate the morphologic characteristics of eyeballs in myopia with three-dimensional magnetic resonance imaging （3-D MRI）. Methods The emmetropia （10 cases, 20 eyes）, low myopia （10 cases,20 eyes）, medium myopia （10 cases,20 eyes）, high myopia （10 cases,20 eyes） were enrolled. Patients which had eye diseases, history of ocular injury or surgery were excluded. In all cases the 3-D MRI were taken for the measurement of the sagittal, horizontal and vertical diameter of eyeball, eyeball volume and the ending points of eye muscle and optic nerve. Results The average value of sagittal, horizontal and vertical length of low myopia, medium myopia and high myopia group were much bigger than those of emmetropia group, especially the axial length. The average value of eyeball volume of myopia group was much bigger than that of emmetropia group. The eyeball, eye muscles and optic nerve were showed clearly in the 3-D MRI. The low and medium myopia group did not present obvious posterior staphyloma. Fifteen of 20 eyeballs in the high myopia group showed posterior staphyloma. Conclusion The sagittal, horizontal and vertical diameters and volume of the eyeball of low myopia, medium myopia and high myopia are significantly bigger than those of emmetropia. The 3-D MRI can show the eyeball shape, eye muscles and optic nerve clearly, which has the certain value in clinical work especially for eye surgery.