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. 2021 Apr;46(4):524-531. doi: 10.1080/02713683.2020.1805769. Epub 2020 Aug 17.
Orbital veins such as the retinal veins and episcleral veins drain into the cavernous sinus, an intracranial venous structure. We studied the effects of acute intracranial pressure (ICP) elevation on episcleral venous pressure, intraocular pressure and retinal vein diameter in an established non-survival pig model.
In six adult female domestic pigs, we increased ICP in 5 mm Hg increments using saline infusion through a lumbar drain. We measured ICP (using parenchymal pressure monitor), intraocular pressure (using pneumatonometer), episcleral venous pressure (using venomanometer), retinal vein diameter (using OCT images) and arterial blood pressure at each stable ICP increment. The average baseline ICP was 5.4 mm Hg (range 1.5-9 mm Hg) and the maximum stable ICP ranged from 18 to 40 mm Hg. Linear mixed models with random intercepts were used to evaluate the effect of acute ICP increase on outcome variables.
With acute ICP elevation, we found loss of retinal venous pulsation and increased episcleral venous pressure, intraocular pressure and retinal vein pressure in all animals. Specifically, acute ICP increase was significantly associated with episcleral venous pressure (β = 0.31; 95% CI 0.14-0.48, < .001), intraocular pressure (β = 0.37, 95%CI 0.24-0.50; < .001) and retinal vein diameter (β = 11.29, 95%CI 1.57-21.00; = .03) after controlling for the effects of arterial blood pressure.
We believe that the ophthalmic effects of acute ICP elevation are mediated by increased intracranial venous pressure producing upstream pressure changes within the orbital and retinal veins. These results offer exciting possibilities for the development of non-invasive ophthalmic biomarkers to estimate acute ICP elevations following significant neuro-trauma.
眼眶静脉（如视网膜静脉和巩膜静脉）汇入颅内静脉结构海绵窦。我们在已建立的非存活猪模型中研究了急性颅内压（ICP）升高对巩膜静脉压、眼内压和视网膜静脉直径的影响。
在 6 只成年雌性家猪中，我们通过腰椎引流管以 5mmHg 的增量向颅内输注生理盐水来升高 ICP。我们在每个稳定的 ICP 增量时测量 ICP（使用实质压力监测仪）、眼内压（使用眼压计）、巩膜静脉压（使用静脉压计）、视网膜静脉直径（使用 OCT 图像）和动脉血压。平均基础 ICP 为 5.4mmHg（范围 1.5-9mmHg），最大稳定 ICP 范围为 18-40mmHg。使用具有随机截距的线性混合模型来评估急性 ICP 升高对结果变量的影响。
随着 ICP 的急性升高，我们发现所有动物的视网膜静脉搏动均丧失，巩膜静脉压、眼内压和视网膜静脉压升高。具体而言，急性 ICP 升高与巩膜静脉压（β=0.31；95%CI 0.14-0.48，<0.001）、眼内压（β=0.37，95%CI 0.24-0.50；<0.001）和视网膜静脉直径（β=11.29，95%CI 1.57-21.00；=0.03）显著相关，控制了动脉血压的影响。
我们认为，急性 ICP 升高的眼部影响是通过颅内静脉压升高引起的眼眶和视网膜静脉内上游压力变化介导的。这些结果为开发非侵入性眼科生物标志物以估计重大神经创伤后急性 ICP 升高提供了令人兴奋的可能性。
