Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Ophthalmology. 2013 Jan;120(1):91-9. doi: 10.1016/j.ophtha.2012.06.054. Epub 2012 Sep 12.
To study the morphologic and functional changes in retinal veins of eyes affected with branch retinal vein occlusion (BRVO) by thin sectioning with optical coherence tomography (OCT).
Prospective, observational, cross-sectional study.
Twenty-five consecutive patients (25 eyes) with acute BRVO.
Major retinal veins, arteries, and arteriovenous (A/V) crossing were examined by sequential thin sectioning by Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). The retinal blood flow was mimicked in vitro and scanned with Spectralis HRA+OCT.
Morphologic characteristics of normal and BRVO-affected retinal vessels seen in OCT sections.
Cross-sectional OCT images revealed physiologic retinal vessels as oval configurations with 4 distinctive hyperreflectivities in a line. The vessel walls showed the innermost and outermost hyperreflectivity, and the blood flow showed internal paired hyperreflectivities with an hourglass shape. No eye with disturbed blood flow due to BRVO showed this internal hyperreflectivity pattern. In vitro, OCT sections of the blood within the glass tube without flow showed homogeneous reflectivities. Increased blood flow velocity resulted in the development of heterogeneous internal reflectivity and hourglass-shaped hyperreflectivities. In all eyes with acute BRVO, sequential sectioning with OCT visualized 3-dimensional vascular architecture and the intravascular conditions at the A/V crossing. At the affected A/V crossing, arterial overcrossing was seen in 17 eyes and venous overcrossing was seen in 8 eyes. In eyes with arterial overcrossing, the retinal vein seemed to run deep under the artery at the A/V crossing, and the venous lumen often appeared to be preserved even at the A/V crossing. In all eyes with venous overcrossing, the retinal vein appeared to be compressed and choked between the internal limiting membrane and the arterial wall at the A/V crossing. Optical coherence tomography sectioning showed intravenous thrombi in 21 eyes, and the thrombi were detected downstream of the A/V crossing in all the cases. The detection of thrombus was significantly associated with ischemic pattern in BRVO (P=0.036).
In eyes with BRVO, sequential thin sections with OCT visualized 3-dimensional retinal vasculature. The present OCT findings suggest that BRVO may occur by 2 different mechanisms, depending on the relative anatomic positions of the crossing vessels.
FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.
通过光学相干断层扫描（OCT）对视网膜分支静脉阻塞（BRVO）患者的视网膜静脉进行薄片检查，研究其形态和功能变化。
前瞻性、观察性、横断面研究。
25 例连续急性 BRVO 患者（25 只眼）。
通过 Spectralis HRA+OCT（海德堡工程公司，德国海德堡）对主要视网膜静脉、动脉和动静脉（AV）交叉进行连续薄片检查。体外模拟视网膜血流，并用 Spectralis HRA+OCT 扫描。
OCT 切片中正常和 BRVO 受累视网膜血管的形态特征。
横截面 OCT 图像显示生理性视网膜血管呈椭圆形，呈线状排列 4 个特征性高反射。血管壁显示最内层和最外层高反射，血流显示内部成对高反射，呈沙漏形。没有因 BRVO 而血流紊乱的眼显示这种内部高反射模式。在体外，无血流的玻璃管内 OCT 切片显示均匀反射率。血流速度增加导致内部反射率不均匀和沙漏形高反射。在所有急性 BRVO 眼中，OCT 连续切片可显示三维血管结构和 AV 交叉处的血管内情况。在受影响的 AV 交叉处，17 只眼出现动脉跨越，8 只眼出现静脉跨越。在动脉跨越的眼中，视网膜静脉似乎在 AV 交叉处位于动脉下方较深的位置，静脉管腔即使在 AV 交叉处也常常保持通畅。在所有静脉跨越的眼中，视网膜静脉似乎在 AV 交叉处被内界膜和动脉壁之间压迫和阻塞。OCT 切片显示 21 只眼存在静脉内血栓，所有病例均在 AV 交叉处下游检测到血栓。血栓的检测与 BRVO 的缺血模式显著相关（P=0.036）。
在 BRVO 眼中，OCT 连续薄片可显示三维视网膜血管。本 OCT 研究结果表明，BRVO 可能通过两种不同的机制发生，这取决于交叉血管的相对解剖位置。
作者没有与本文讨论的材料有任何专有或商业利益。
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