Background The quantitative analysis of the relationship between the vitreous volume with diopter and axial length in high myopic eye can offer a valuable basis for relevant clinical research. However, how to measure the ocular volume in vivo is a problem. Objective This study was to measure the eyeball volumes with magnetic resonance imaging ( MRI) and compare the difference of ocular volume between emmetropic and high-myopic eyes in order to explore the influent factors of changes of eyeball volumes. Methods The volumes of ocular anterior segment,lens and vitreous were measured using MRI( 1.5-T) in 60 emmetropic eyes and 60 high-myopic eyes. The ocular axial lengths of the subjects were measured by A-scan ultrasonography. The alterations of vitreous volumes with the changes of axial lengths and diopters were evaluated by linear regression analysis. Written informed consent was obtained from each patient before any medical examination. Results The mean diopters of high myopic eyes was ( - 15. 62 ± 8. 27 ) D and the mean axial lengths were ( 28. 68 ± 2. 68 ) mm, showing a significantly positive correlation between them(R2=0. 830,P = 0. 000). The mean total ocular volumes were(7.46±0. 89)ml3 and those of vitreous were ( 6. 90 ± 0. 8 ) ml3 in the high-myopic eyes with a significant increase in comparison with emmetropic eyes [ ( 6. 00 ± 0. 35 ) ml3 and ( 5. 41 ±0. 32 ) ml3 ] ( t = - 11. 846, P = 0. 000; t = - 12. 1, P = 0. 000 ). However,no significant differences were found in the anterior segment volumes and lens volumes between high myopic eyes and emmetropic eyes (t = 1. 23, P = 0. 220; t = -0. 483 , P = 0. 630 ). The vitreous volumes of high myopic eyes were significantly correlated with the diopters and the axial lengths (R2 =0. 75 ,P = 0. 000 ;R2 =0. 85 ,P = 0. 000) ,and so were the total ocular volumes (R2 = 0. 7543, P = 0. 000; R2 = 0. 8413, P = 0. 000). Conclusion The alteration of vitreous volumes is a mainly cause of difference of total ocular volume in ammetropic eyes. In high myopic eye, vitreous volume has a good linear correlation with refractive error and axial length, which may offer valuable information for vitrectomy.%背景 定量评估高度近视眼玻璃体容积改变与屈光度、眼轴长度之间的关系能够为高度近视的临床研究提供有价值的依据,利用磁共振成像(MRI)技术直接进行活体眼球容积测量具有较好的临床价值.目的 应用MRI测量正视者及高度近视患者眼球内各部分空间容积,比较2组间眼球内各部分容积的差异并明确与眼球容积变化相关的因素.方法采用MRI系统(1.5-T系统)对屈光度为-0.25～+0.50 D的60例正常眼和>6.00 D的60例高度近视眼进行眼前节、晶状体、玻璃体腔容积测量并进行定量比较,采用A型超声对眼轴长度进行测量,采用线性回归法分析高度近视眼玻璃体容积及球内总容积随眼轴长度和屈光度的变化而变化的规律.结果 高度近视组的平均屈光度为(-15.62±8.27)D,A型超声测得眼轴前后径均值为(28.68±2.68)mm,二者呈明显正相关(R2=0.830,P=0.000).高度近视组的球内总容积(7.46±0.89)ml3和玻璃体腔容积(6.90±0.89)ml3明显大于正视组的球内总容积(6.00±0.35)ml3和玻璃体腔容积(5.41±0.32)ml3,差异均有统计学意义(t=-11.846,P=0.000;t=-12.100,P=0.000);而2组之间眼前节容积和晶状体容积的差异均无统计学意义(t=1.230,P=0.220,t=-0.483,P=0.630).高度近视组的玻璃体腔容积与屈光度、眼轴长度均呈高度正相关(R2=0.750,P=0.000;R2=0.850,P=0.000);高度近视组的球内总容积与屈光度、眼轴长度均呈高度正相关(R2=0.754,P=0.000;R2=0.841,P=0.000).结论 玻璃体腔容积的差异是导致不同屈光度眼球内容积差异的主要因为,高度近视眼的玻璃体腔容积与屈光度及眼轴长度呈线性关系,对玻璃体手术有较重要的参考价值.
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