The Posterior Location of the Dilator Muscle Induces Anterior Iris Bowing during Dilation, Even in the Absence of Pupillary Block
The Posterior Location of the Dilator Muscle Induces Anterior Iris Bowing during Dilation, Even in the Absence of Pupillary Block
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DOI：
10.1167/iovs.11-8408
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发表时间：
2012-03-01
影响因子：
4.4
通讯作者：
Barocas, Victor H.
中科院分区：
文献类型：
--
作者：
Amini, Rouzbeh;Whitcomb, Julie E.;Barocas, Victor H.
目的.目的：探讨扩张器的位置对虹膜前弯的影响。并行进行了体内人体研究、离体猪实验和计算机模拟计算模型。应用时域裂隙灯光学相干断层扫描（SL-OCT）测量扩张前后虹膜前曲。所有患者（n = 7）均接受了激光周边虹膜切开术，以消除任何瞳孔阻滞由于原发性闭角型青光眼。在离体实验中，将分离的猪虹膜（n = 30）固定在外周并浸入充氧的Krebs-Ringer缓冲液中。通过添加2.5%苯乙双胍和1%托吡卡胺来药物诱导扩张。使用内部光学相干断层扫描（OCT）系统获得扩张前后的虹膜图像。还基于来自初始OCT图像的虹膜的典型几何形状开发了有限元模型。虹膜被建模为neo-Hookean实体，并且活动肌肉组件仅应用于指定为虹膜的区域。在这两个实验中，观察到扩张后的曲率增加和弦长减少。在体内和体外实验中，扩张期间曲率弦长比显著增加。只有在正确的解剖位置使用扩张器时，计算机模拟结果才与实验结果一致。扩张器的后部位置通过非瞳孔阻滞依赖机制导致虹膜前部弯曲。（Invest Ophthalmol维斯科学。2012;53：1188-1194）DOI：10.1167/iovs.11-8408
PURPOSE. To examine the effect of the posterior location of the dilator on iris anterior curvature during dilation.METHODS. An in vivo human study, an ex vivo porcine experiment, and an in silico computational model were performed in parallel. Iris anterior curvature was measured in vivo before and after dilation by time-domain slit lamp optical coherence tomography (SL-OCT). All patients (n = 7) had undergone laser peripheral iridotomy to eliminate any pupillary block due to primary angle-closure glaucoma. In the ex vivo experiments, isolated porcine irides (n = 30) were secured at the periphery and immersed in an oxygenated Krebs-Ringer buffer. Dilation was induced pharmaceutically by the addition of 2.5% phenylephrine and 1% tropicamide. An in-house optical coherence tomography (OCT) system was used to obtain iris images before and after dilation. A finite element model was also developed based on typical geometry of the iris from the initial OCT image. The iris was modeled as a neo-Hookean solid, and the active muscle component was applied only to the region specified as the dilator.RESULTS. An increase in curvature and a decrease in chord length after dilation were observed in both experiments. In both the in vivo and ex vivo experiments, the curvature-tochord length ratio increased significantly during dilation. Computer simulations agreed well with the experimental results only when the proper anatomic position of dilator was used.CONCLUSIONS. The posterior location of the dilator contributes to the anterior iris bowing via a nonpupillary block dependent mechanism. (Invest Ophthalmol Vis Sci. 2012;53:1188-1194) DOI:10.1167/iovs.11-8408