Finite element modeling of effects of tissue property variation on human optic nerve tethering during adduction

Joseph Park; Andrew Shin; Joseph L Demer

doi:10.1038/s41598-022-22899-2

Finite element modeling of effects of tissue property variation on human optic nerve tethering during adduction

Sci Rep. 2022 Nov 8;12(1):18985. doi: 10.1038/s41598-022-22899-2.

Authors

Joseph Park^{1

2}, Andrew Shin³, Joseph L Demer^{4

5

6

7}

Affiliations

¹ Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, 90095-7002, USA.
² Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, USA.
³ Intelon Optics Inc., Lexington, MA, USA.
⁴ Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, 90095-7002, USA. jld@jsei.ucla.edu.
⁵ Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, USA. jld@jsei.ucla.edu.
⁶ Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA, USA. jld@jsei.ucla.edu.
⁷ Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA. jld@jsei.ucla.edu.

Abstract

Tractional tethering by the optic nerve (ON) on the eye as it rotates towards the midline in adduction is a significant ocular mechanical load and has been suggested as a cause of ON damage induced by repetitive eye movements. We designed an ocular finite element model (FEM) simulating 6° incremental adduction beyond the initial configuration of 26° adduction that is the observed threshold for ON tethering. This FEM permitted sensitivity analysis of ON tethering using observed material property variations in measured hyperelasticity of the anterior, equatorial, posterior, and peripapillary sclera; and the ON and its sheath. The FEM predicted that adduction beyond the initiation of ON tethering concentrates stress and strain on the temporal side of the optic disc and peripapillary sclera, the ON sheath junction with the sclera, and retrolaminar ON neural tissue. However, some unfavorable combinations of tissue properties within the published ranges imposed higher stresses in these regions. With the least favorable combinations of tissue properties, adduction tethering was predicted to stress the ON junction and peripapillary sclera more than extreme conditions of intraocular and intracranial pressure. These simulations support the concept that ON tethering in adduction could induce mechanical stresses that might contribute to ON damage.

Publication types

Research Support, Non-U.S. Gov't
Research Support, N.I.H., Extramural

MeSH terms

Biomechanical Phenomena
Eye Movements
Finite Element Analysis
Humans
Intraocular Pressure
Optic Disk* / physiology
Optic Nerve* / physiology
Sclera / physiology

Abstract

Publication types

MeSH terms

Grants and funding