Multi-scale analysis of optic chiasmal compression by finite element modelling.
The precise mechanism of bitemporal hemianopia (a type of partial visual field defect) is still not clear. Previous work has investigated this problem by studying the biomechanics of chiasmal compression caused by a pituitary tumour growing up from below the optic chiasm. A multi-scale analysis was performed using finite element models to examine both the macro-scale behaviour of the chiasm and the micro-scale interactions of the nerve fibres within it using representative volume elements. Possible effects of large deflection and non-linear material properties were incorporated. Strain distributions in the optic chiasm and optic nerve fibres were obtained from these models. The results of the chiasmal model agreed well with the limited experimental results available, indicating that the finite element modelling can be a useful tool for analysing chiasmal compression. Simulation results showed that the strain distribution in nasal (crossed) nerve fibres was much more nonuniform and locally higher than in temporal (uncrossed) nerve fibres. This strain difference between nasal and temporal nerve fibres may account for the phenomenon of bitemporal hemianopia.
School of Engineering and Information Technology, University of New South Wales Canberra, ACT, Australia. Electronic address: Xiaofei87@live.com.
Xiaofei
X
Wang
School of Engineering and Information Technology, University of New South Wales Canberra, ACT, Australia.
Andrew J
AJ
Neely
Queen׳s University Belfast, Belfast, Northern Ireland, UK; Belfast Health and Social Care Trust, Belfast, Northern Ireland, UK.
Gawn G
GG
McIlwaine
The Canberra Hospital, Canberra, ACT, Australia; Australian National University, Canberra, ACT, Australia.
Christian J
CJ
Lueck
D001369:Axons / Q000502:physiology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D020342:Finite Element Analysis; D006423:Hemianopsia / Q000503:physiopathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008953:Models, Anatomic; D009412:Nerve Fibers / Q000473:pathology; D009897:Optic Chiasm / Q000502:physiology*; D011312:Pressure; D014785:Vision, Ocular / Q000502:physiology*
Bitemporal hemianopia; Chiasmal compression; Finite element modelling; Multi-scale; Nerve failure