Virtual reality training improves accommodative facility and accommodative range

AIM: To evaluate the effects of virtual reality(VR) training on different parameters of vision.METHODS: Sixty individuals ranged 18-60 years old with asthenopia were randomly divided into short-term(n=40) and long-term(n=20) treatment groups. They were given a specially designed VR training device only once for 15 min or 3-4 times a day for 15 min each time for 1 mo. The visual acuity, spherical equivalent, accommodative range, accommodative facility, pupil size, and visual fatigue were evaluated before(control) and after VR training. RESULTS: The visual acuity, accommodative range, and accommodative facility increased in subjects of the shortterm treatment group, whereas their pupil size contracted significantly. No significant changes in spherical equivalent and visual fatigue were observed. The changes in distant vision and corrected visual acuity were positively correlated with those in pupil size, but not with spherical equivalent. The accommodative range and accommodative facility improved significantly in subjects of the long-term treatment group. No significant changes in visual acuity, spherical equivalent, pupil size, and visual fatigue were noted. CONCLUSION: VR training can improve the accommodative range and accommodative facility of human eyes. Although short-term VR training can transiently improve vision, which probably due to bright light adaptation, there is no evidence that it can improve myopia.

Analyzing and modeling rheological behavior of liver fibrosis in rats using shear viscoelastic moduli

The process of liver fibrosis changes the rheological properties of liver tissue.This study characterizes and compares liver fibrosis stages from F0 to F4 in rats in terms of shear viscoelastic moduli.Here two viscoelastic models,the Zener model and Voigt model,were applied to experimental data of rheometer tests and then values of elasticity and viscosity were estimated for each fibrosis stage.The results demonstrate that moderate fibrosis（≤F2） has a good correlation with liver viscoelasticity.The mean Zener elasticity E1 increases from（0.452±0.094） kPa（F0） to（1.311±0.717） kPa（F2）,while the mean Voigt elasticity E increases from（0.618±0.089） kPa（F0） to（1.701±0.844） kPa（F2）.The mean Zener viscosity increases from（3.499±0.186） Pa·s（F0） to（4.947±1.811） Pa·s（F2） and the mean Voigt viscosity increases from（3.379±0.316） Pa·s（F0） to（4.625±1.296） Pa·s（F2）.Compared with viscosity,the elasticity shows smaller variations at stages F1 and F2 no matter what viscoelastic model is used.Therefore,the estimated elasticity is more effective than viscosity for differentiating the fibrosis stages from F0 to F2.