Kedar Sachin, Tong Junfei, Bader John, Havens Shane, Fan Shan, Thorell William, Nelson Carl, Gu Linxia, High Robin, Gulati Vikas, Ghate Deepta
Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA.
Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, USA.
Curr Eye Res. 2022 Feb;47(2):304-311. doi: 10.1080/02713683.2021.1952604. Epub 2021 Dec 12.
The lamina cribrosa (LC) is a layer of fenestrated connective tissue tethered to the posterior sclera across the scleral canal in the optic nerve head (ONH). It is located at the interface of intracranial and intraocular compartments and is exposed to intraocular pressure (IOP) anteriorly and intracranial pressure (ICP) or Cerebrospinal fluid (CSF) pressure (CSFP) posteriorly. We hypothesize that the pressure difference across LC will determine LC position and meridional diameter of scleral canal (also called Bruch's membrane opening diameter; BMOD).
We enrolled 19 human subjects undergoing a medically necessary lumbar puncture (LP) to lower CSFP and 6 anesthetized pigs, whose ICP was increased in 5 mm Hg increments using a lumbar catheter. We imaged ONH using optical coherence tomography and measured IOP and CSFP/ICP at baseline and after each intervention. Radial tomographic ONH scans were analyzed by two independent graders using ImageJ, an open-source software. The following ONH morphological parameters were obtained: BMOD, anterior LC depth and retinal thickness. We modeled effects of acute CSFP/ICP changes on ONH morphological parameters using ANOVA (human study) and generalized linear model (pig study).
For 19 human subjects, CSFP ranged from 5 to 42 mm Hg before LP and 2 to 19.4 mm Hg after LP. For the six pigs, baseline ICP ranged from 1.5 to 9 mm Hg and maximum stable ICP ranged from 18 to 40 mm Hg. Our models showed that acute CSFP/ICP changes had no significant effect on ONH morphological parameters in both humans and pigs.
We conclude that ONH does not show measurable morphological changes in response to acute changes of CSFP/ICP. Proposed mechanisms include compensatory and opposing changes in IOP and CSFP/ICP and nonlinear or nonmonotonic effects of IOP and CSFP/ICP across LC.
筛板（LC）是一层有窗孔的结缔组织，通过视神经乳头（ONH）的巩膜管与后巩膜相连。它位于颅内和眼内腔室的界面，前部暴露于眼内压（IOP），后部暴露于颅内压（ICP）或脑脊液（CSF）压力（CSFP）。我们假设，穿过LC的压力差将决定LC的位置和巩膜管的子午线直径（也称为布鲁赫膜开口直径；BMOD）。
我们招募了19名因医疗需要进行腰椎穿刺（LP）以降低CSFP的人类受试者和6只麻醉猪，通过腰椎导管以5 mmHg的增量增加其ICP。我们使用光学相干断层扫描对ONH成像，并在基线和每次干预后测量IOP和CSFP/ICP。两名独立的评分者使用开源软件ImageJ对ONH的径向断层扫描进行分析。获得了以下ONH形态学参数：BMOD、前LC深度和视网膜厚度。我们使用方差分析（人类研究）和广义线性模型（猪研究）对急性CSFP/ICP变化对ONH形态学参数的影响进行建模。
对于19名人类受试者，LP前CSFP范围为5至42 mmHg，LP后为2至19.4 mmHg。对于6只猪，基线ICP范围为1.5至9 mmHg，最大稳定ICP范围为18至40 mmHg。我们的模型表明，急性CSFP/ICP变化对人类和猪的ONH形态学参数均无显著影响。
我们得出结论，ONH在响应CSFP/ICP的急性变化时未显示出可测量的形态学变化。提出的机制包括IOP和CSFP/ICP的代偿性和相反变化，以及IOP和CSFP/ICP穿过LC的非线性或非单调效应。
