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Junfei Tong, Deepta Ghate, Sachin Kedar, Linxia Gu; Relative contributions of intracranial pressure and intraocular pressure in lamina cribrosa behavior. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3168.
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© ARVO (1962-2015); The Authors (2016-present)
The pathogenesis of optic nerve head (ONH) damage has been associated with translaminar pressure gradient which is the difference between intraocular pressure (IOP) and intracranial pressure (ICP) across the lamina cribrosa (LC). While the role of IOP on ONH mechanics has been well studied, the quantitative contribution of ICP remains unclear. The goal of this work is to characterize the relative contribution of IOP and ICP on the LC behavior, specifically, LC strain and LC displacement.
An axially symmetric FE model of the ONH (Figure 1) was constructed with geometric dimensions obtained from literature (Sigal et al. 2004), except the addition of the retro-orbital subarachnoid space ensheathed by pia and dura mater as well as an elongated optic nerve. The pressure loading includes central retinal artery pressure at 55 mmHg, ICP ranging from 5 to 15 mmHg and IOP ranging from 10 to 21 mmHg. A parametrical study was then carried out to quantify the peak strain and LC displacement, where the 95th percentile of the maximum principle strain in LC was defined as the peak strain. A linear regression analysis was conducted to predict the peak strain and LC displacement based on the changes in both ICP and IOP.
Both decreased ICP and increased IOP led to larger strain and displacement of LC as shown in Fig.2. The regression correlation coefficients for LC peak strain are -0.0288 for ICP and 0.114 for IOP, the coefficient ratio between IOP and ICP is -3.96. The regression correlation coefficients for LC displacement are -1.247 for ICP and 1.756 for IOP, the coefficient ratio between IOP and ICP is -1.4.
IOP and ICP have opposing influence on LC strain and displacement. IOP changes have a larger impact on peak strain and LC displacement as compared to ICP changes. Specifically, the contribution of IOP to peak strain is approximately 4 times as that of ICP; the contribution of IOP to LC displacement is 1.4 times as that of ICP.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1a: ONH geometry Full view; 1b: ONH geometry zoom-in view.
Figure 2a: Probability distribution of maximum principal strain in LC; 2b: LC anterior surface displacement
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