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
Objective:To identify the types and causes of eye injury in industrial workers. Methods: A cross sectional study of the pattern of ocular injuries in Delta state of Nigeria was carried out over 3 months. Five hundred ...Objective:To identify the types and causes of eye injury in industrial workers. Methods: A cross sectional study of the pattern of ocular injuries in Delta state of Nigeria was carried out over 3 months. Five hundred workers were interviewed and examined using the Snellen's chart, pen-torch, direct ophthalmoscope, magnifying loupe and the Perkin's hand-held applanation tonometer. Results: All the 500 workers were males. One hundred and twenty-three workers (24.6%) reported a history of ocular injury at work. The most common causative agents were sand dust, 53 workers (25.1%); cake dust, 27 workers (12.8%) and chemicals, 32 workers (15.1%). The main types of ocular injury were corneal/ conjunctival foreign bodies, 79 workers (64.2%); burns, 35 workers (28.5%) and blunt injury, 9 workers (7.3%). Only 36 (7.2%) workers used protective eye devices at work. Thirteen workers (2.6%) developed monocular blindness from ocular injury. Conclusion: Ocular injury at work is common and few workers wear protective devices at work in industries in Delta state, Nigeria. Industrial workers should have regular eye services and wear eye safety devices at work.展开更多
目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular ...目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular reflex,VOR)的平均增益值及各半规管之间的不对称比进行比较。结果40例民航飞行学员右侧水平、前、后半规管VOR增益值分别为1.05±0.07、0.92±0.13、0.81±0.09,左侧水平、前、后半规管VOR增益值分别为1.00±0.06、0.85±0.10、0.86±0.10,所有受试者均未见补偿性扫视。双侧水平、左前-右后、右前-左后半规管VOR增益值不对称比分别为5.56%±3.64%、9.65%±4.74%、8.68%±7.07%。结论本研究建立了民航飞行学员vHIT正常参考值,为民航飞行学员的选拔及前庭功能鉴定提供了客观依据。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.
文摘Objective:To identify the types and causes of eye injury in industrial workers. Methods: A cross sectional study of the pattern of ocular injuries in Delta state of Nigeria was carried out over 3 months. Five hundred workers were interviewed and examined using the Snellen's chart, pen-torch, direct ophthalmoscope, magnifying loupe and the Perkin's hand-held applanation tonometer. Results: All the 500 workers were males. One hundred and twenty-three workers (24.6%) reported a history of ocular injury at work. The most common causative agents were sand dust, 53 workers (25.1%); cake dust, 27 workers (12.8%) and chemicals, 32 workers (15.1%). The main types of ocular injury were corneal/ conjunctival foreign bodies, 79 workers (64.2%); burns, 35 workers (28.5%) and blunt injury, 9 workers (7.3%). Only 36 (7.2%) workers used protective eye devices at work. Thirteen workers (2.6%) developed monocular blindness from ocular injury. Conclusion: Ocular injury at work is common and few workers wear protective devices at work in industries in Delta state, Nigeria. Industrial workers should have regular eye services and wear eye safety devices at work.
文摘目的建立民航飞行学员视频头脉冲试验(video head impulse test,vHIT)正常参考值,为民航飞行学员前庭功能的准确评估提供参考依据。方法随机选取40例尚处于飞行理论学习阶段的民航飞行学员进行vHIT检测,对前庭-眼反射(vestibulo-ocular reflex,VOR)的平均增益值及各半规管之间的不对称比进行比较。结果40例民航飞行学员右侧水平、前、后半规管VOR增益值分别为1.05±0.07、0.92±0.13、0.81±0.09,左侧水平、前、后半规管VOR增益值分别为1.00±0.06、0.85±0.10、0.86±0.10,所有受试者均未见补偿性扫视。双侧水平、左前-右后、右前-左后半规管VOR增益值不对称比分别为5.56%±3.64%、9.65%±4.74%、8.68%±7.07%。结论本研究建立了民航飞行学员vHIT正常参考值,为民航飞行学员的选拔及前庭功能鉴定提供了客观依据。
