Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was bip...Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was biphasic and consisted of a solid phase(connective tissues)and a fluid phase(blood).The LC was viscoelastic as characterized by a stress-relaxation test.We applied arterial pressures at 18 entry sites(posterior ciliary arteries)and venous pressures at 4 exit sites(vortex veins).The heart rate was varied from 60 bpm to 120 bpm(increment:20 bpm).We reported the ocular pulse amplitude(OPA),pulse volume,optic nerve head(ONH)deformations and the dynamic modulus of the LC at different heart rates.Results With an increasing heart rate,the OPA decreased by 0.04 mmHg for every 10 bpm increase.The pulse volume also exhibited a linear relationship with heart rate,and decreased by 0.13 L.In addition,the storage modulus and the loss modulus of the LC center increased by 0.014 MPa and 0.04 MPa,respectively for every 10 pm increase in heart rate.Conclusions Our model predicted that the OPA,the pulse volume the ONH deformation decreased at a faster heartrate.We also found that the viscoelastic LC became stiffer with an increasing heart rate.Further studies are required to explore the potential links with the vascular dysregulation and axonal loss in glaucoma.展开更多
文摘Objective To study the effect of changing heart rate on the ocular pulse and optic nerve head deformations with a viscoelastic lamina cribrosa.Methods An FE model of a healthy eye was reconstructed.The choroid was biphasic and consisted of a solid phase(connective tissues)and a fluid phase(blood).The LC was viscoelastic as characterized by a stress-relaxation test.We applied arterial pressures at 18 entry sites(posterior ciliary arteries)and venous pressures at 4 exit sites(vortex veins).The heart rate was varied from 60 bpm to 120 bpm(increment:20 bpm).We reported the ocular pulse amplitude(OPA),pulse volume,optic nerve head(ONH)deformations and the dynamic modulus of the LC at different heart rates.Results With an increasing heart rate,the OPA decreased by 0.04 mmHg for every 10 bpm increase.The pulse volume also exhibited a linear relationship with heart rate,and decreased by 0.13 L.In addition,the storage modulus and the loss modulus of the LC center increased by 0.014 MPa and 0.04 MPa,respectively for every 10 pm increase in heart rate.Conclusions Our model predicted that the OPA,the pulse volume the ONH deformation decreased at a faster heartrate.We also found that the viscoelastic LC became stiffer with an increasing heart rate.Further studies are required to explore the potential links with the vascular dysregulation and axonal loss in glaucoma.
