Berkowitz B A, Penn J S
Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan 48201, USA.
Invest Ophthalmol Vis Sci. 1998 Apr;39(5):840-5.
Present technologies are not able to determine which retinas are at risk for the development of neovascularization in retinopathy of prematurity (ROP). In this study, the authors evaluated whether a novel magnetic resonance imaging (MRI) method could be used to identify differences between control retinas and those that will develop neovascularization in the newborn rat model of retinopathy of prematurity (ROP).
MRI and a 2-minute carbogen (95% O2/5% CO2) inhalation challenge (see ref. 11) were used to measure noninvasively the change in the posterior vitreous oxygen tension in specific locations across the full extent of the retina in day-12 rats raised in either room air (control, n = 7) or variable oxygen conditions (experimental ROP, n = 7). The experimental ROP animals were examined 2 days before the onset of neovascularization.
In the ROP group, the response to carbogen was lower (P < 0.05) at every distance from the optic nerve than in the control group. Within the ROP group, the vascular midperipheral retinal reaction to carbogen, 1 to 2 mm from the optic nerve, was as low as that from the avascular periphery, 2 to 3 mm from the optic nerve. Although the vascular central retinal response to carbogen, 0 to 1 mm from the optic nerve, was greater than either the vascular midperipheral retina or the avascular periphery in the ROP group, theoretically this difference could be caused by oxygen diffusing from the hyaloidal circulation.
Carbogen-challenge MRI seems to be a useful tool for assessing the risk of retinal neovascularization in the newborn rat ROP model. This MRI method has potential clinical applicability, for example, because effective laser therapy with retinal sparing may be possible if focal photocoagulation, guided by an MRI map, is performed.
目前的技术无法确定哪些视网膜在早产儿视网膜病变（ROP）中存在发生新生血管形成的风险。在本研究中，作者评估了一种新型磁共振成像（MRI）方法是否可用于识别新生大鼠早产儿视网膜病变（ROP）模型中对照视网膜与将发生新生血管形成的视网膜之间的差异。
使用MRI和2分钟的二氧化碳混合气（95%氧气/5%二氧化碳）吸入激发试验（见参考文献11），对饲养在常氧环境（对照组，n = 7）或可变氧环境（实验性ROP组，n = 7）中的12日龄大鼠，在视网膜整个范围内的特定位置非侵入性地测量玻璃体后段氧张力的变化。在新生血管形成开始前2天对实验性ROP动物进行检查。
在ROP组中，距视神经每个距离处对二氧化碳混合气的反应均低于对照组（P < 0.05）。在ROP组内，距视神经1至2 mm的视网膜血管中周部对二氧化碳混合气的反应与距视神经2至3 mm的无血管周边部一样低。虽然距视神经0至1 mm的视网膜血管中央部对二氧化碳混合气的反应大于ROP组中的视网膜血管中周部或无血管周边部，但理论上这种差异可能是由玻璃体循环中扩散的氧气引起的。
二氧化碳混合气激发MRI似乎是评估新生大鼠ROP模型中视网膜新生血管形成风险的一种有用工具。例如，这种MRI方法具有潜在的临床适用性，因为如果在MRI图谱引导下进行局部光凝，可能实现保留视网膜的有效激光治疗。
