Pressure balance and imbalance in the optic nerve chamber： The Beijing Intracranial and Intraocular Pressure （iCOP） Study

To determine the interdependence of intracranial pressure （ICP） and intraocular pressure （IOP） and how it affects optic nerve pressures, eight normal dogs were examined using pressure-sensing probes implanted into the left ventricle, lumbar cistern, optic nerve subarachnoid space in the left eye, an...

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Published in中国科学：生命科学英文版 no. 5; pp. 495 - 503
Main Author Ruowu Houi Zheng Zhang Diya Yang Huaizhou Wang Weiwei Chen Zhen Li Jinghong Sang Sumeng Liu Yiwen Cao Xiaobin Xie Ruojing Ren Yazhuo Zhang Bernhard A. Sabel Ningli Wang
Format Journal Article
LanguageEnglish
Published 2016
Subjects
不平衡
北京
压力平衡
压力梯度
眼压
蛛网膜下腔
视神经
颅内压
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Summary:To determine the interdependence of intracranial pressure （ICP） and intraocular pressure （IOP） and how it affects optic nerve pressures, eight normal dogs were examined using pressure-sensing probes implanted into the left ventricle, lumbar cistern, optic nerve subarachnoid space in the left eye, and anterior chamber in the left eye. This allowed ICP, lumbar cistern pressure （LCP）, optic nerve subarachnoid space pressure （ONSP） and IOP to be simultaneously recorded. After establishing baseline pressure levels, pressure changes that resulted from lowering ICP （via shunting cerebrospinal fluid （CSF） from the ventricle） were recorded. At baseline, all examined pressures were different （ICP〉LCP〉ONSP）, but correlated （P〈0.001）. As ICP was lowered during CSF shunting, IOP also dropped in a parallel time course so that the trans-lamina cribrosa gradient （TLPG） remained stable （ICP-IOP dependent zone）. However, once ICP fell below a critical breakpoint, ICP and IOP became uncou- pled and TLPG changed as ICP declined （ICP-IOP independent zone）. The optic nerve pressure gradient （ONPG） and trans-optic nerve pressure gradient （TOPG） increased linearly as ICP decreased through both the ICP-IOP dependent and in- dependent zones. We conclude that ICP and IOP are coupled in a specific pressure range, but when ICP drops below a critical point, IOP and ICP become uncoupled and TLPG increases. When ICP drops, a rise in the ONPG and TOPG creates more pressure and reduces CSF flow around the optic nerve. This change may play a role in the development and progression of various ophthalmic and neurological diseases, including glaucoma.
Bibliography:glaucoma, optic neuropathy, trans-lamina cribrosa pressure gradient （TLPG）, trans-optic canal pressure gradient（TCPG）, trans-optic nerve pressure gradient （TOPG）, optic nerve pressure gradient （ONPG）
11-5841/Q
To determine the interdependence of intracranial pressure （ICP） and intraocular pressure （IOP） and how it affects optic nerve pressures, eight normal dogs were examined using pressure-sensing probes implanted into the left ventricle, lumbar cistern, optic nerve subarachnoid space in the left eye, and anterior chamber in the left eye. This allowed ICP, lumbar cistern pressure （LCP）, optic nerve subarachnoid space pressure （ONSP） and IOP to be simultaneously recorded. After establishing baseline pressure levels, pressure changes that resulted from lowering ICP （via shunting cerebrospinal fluid （CSF） from the ventricle） were recorded. At baseline, all examined pressures were different （ICP〉LCP〉ONSP）, but correlated （P〈0.001）. As ICP was lowered during CSF shunting, IOP also dropped in a parallel time course so that the trans-lamina cribrosa gradient （TLPG） remained stable （ICP-IOP dependent zone）. However, once ICP fell below a critical breakpoint, ICP and IOP became uncou- pled and TLPG changed as ICP declined （ICP-IOP independent zone）. The optic nerve pressure gradient （ONPG） and trans-optic nerve pressure gradient （TOPG） increased linearly as ICP decreased through both the ICP-IOP dependent and in- dependent zones. We conclude that ICP and IOP are coupled in a specific pressure range, but when ICP drops below a critical point, IOP and ICP become uncoupled and TLPG increases. When ICP drops, a rise in the ONPG and TOPG creates more pressure and reduces CSF flow around the optic nerve. This change may play a role in the development and progression of various ophthalmic and neurological diseases, including glaucoma.
ISSN:1674-7305
1869-1889