Predictive index based on minimum corneal thickness and symmetry index back of Sirius for early diagnosis of keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To construct and validate a diagnostic model for early detection of keratoconus based on parameters in Sirius.METHODS: The study comprised of 46 early keratoconus eyes(including 20 right eyes and 26 left eyes in 34 patients)and 46 age- and gender-matched normal eyes(including the right eyes of 46 patients)in the prediction group. The predictive index was constructed using LASSO and Logistic regression analyses based on the topographic, pachymetric and aberrometry variables of Sirius. There were 23 early keratoconus eyes categorized as suspected keratoconus cases by Sirius(including 12 right eyes and 11 left eyes in 23 patients)and 23 age- and gender-matched normal eyes(including the right eyes of 23 patients)included in the application cohort. External validation of predictors was performed for the application cohort.RESULTS: Sirius Keratoconus Index(SKI)was calculated based on the minimum corneal thickness and symmetry index back of Sirius. Highest AUC values were obtained in the prediction group(AUC=0.932)after Logistic regression analysis. The cut-off value of SKI was set at 0.44. Then, the receiver operating characteristic(ROC)curve, calibration plot and nomogram of the diagnostic formula were analyzed for the prediction cohort in detail. Finally, the accuracy of the SKI was evaluated in the application cohort; the sensitivity was 91% and the specificity was 96%.CONCLUSION: SKI based on minimum corneal thickness and symmetry index back of Sirius is a simple and effective method for early detection of keratoconus in the preoperative screening for refractive surgery.

Static Balance Function in Stroke Patients: A Plantar Pressure Analysis / 中国康复理论与实践

Objective:To explore the mechanism of balance control after stroke by plantar pressure analysis. Methods:From July to December, 2019, twelve stroke subjects (stroke group) and 30 normal subjects (control group) were recruited in the rehabilitation department of our hospital. Both groups were measured plantar pressure in eyes open and closed conditions. The kinematic parameters, dynamic parameters, plantar pressure center (CoP), symmetry index (SI), symmetry angle (SA) and Romberg quotient (RQ) were calculated. Results:Compared with eyes open condition, the average Y and maximum swing of the control group increased significantly in eyes closed condition (P < 0.01); moreover, the ball length, average speed and maximum swing increased significantly in the stroke group (P <0.05). Compared with the control group, the area of the ellipse (|t| > 3.509, P < 0.001) and the average X (|Z|> 2.311, P < 0.05) significantly increased both in eyes open and closed condition, whereas the maximum swing (Z = -3.118, P < 0.01) increased significantly in eyes closed condition in the stroke group. The RQ of ball length was significantly more in the stroke group than in the control group (t = -3.570, P < 0.01). There was no significant difference in SI and SA of all parameters between the eyes open and closed condition in two groups (P > 0.05). Compared with the control group, load SI, overall load SI, forefoot load SI, area SI and forefoot area SI increased in both the eyes open and closed conditions in the stroke group (t > 2.344, P < 0.05), whereas load SA, overall load SA, forefoot load SA, area SA, forefoot area SA increased (|t|> 2.297, P < 0.05), hindfoot load SA increased only in eyes open condition (t = -2.485, P < 0.05), and hindfoot area SA increased only in eyes closed condition (t = -2.132, P < 0.05). In the control group, CoP was mainly distributed in the negative direction of Y axis when the eyes were open and closed, while CoP in the stroke group was relatively discrete, and the distribution on X axis was more obvious than that of the control group. Conclusion:The balance control of stroke patients might depend on visual compensation, and the plantar pressure analysis system could be used to evaluate the balance function in stroke patients.

Efficacy of a continuous symmetry index in detecting the symmetry of sagittal lower limb joint angle at 3-D gait analysis of healthy youth female / 实用医学杂志

Objective To investigate the efficacy of a continuous symmetry index (CSI) in detecting the symmetry of sagittal lower limb joint angle at 3?demensional gait analysis of healthy youth female. Methods A total of 22 healthy female were included in the study.Gait analysis was conducted for two conditions: walk at com?fortable walking speed on barefoot (BF) and in neutral running shoe (NS). Continuous symmetry index was computed with the data of bilateral hip ,knee and ankle joint angle in the sagittal motion plane separately or holistically. Results CSIswere found increased in the sagittal plane of all lower limb joint angle both focally or holistically. There is no significant difference in CSI of hip joint angle ,knee joint angle and in the integrated CSI between the two conditions ,while CSI of ankle joint angle when walk barefoot was significantly lower than that of walk in neutral running shoe (BF:7.6±3.5 vs. NS 9.5±2.8,P=0.013). Conclusion Asymmetry lies in the sagittal motion plane of lower limb joint angles. CSI is a potent tool for the detection of gait symmetry.

Analysis on plantar force parameters of gait under different simulated gravities / 医用生物力学

Objective To investigate the plantar force characteristics during human walking and running under different gravity environment. Methods Seven healthy male volunteers walked and ran in vertical position on a weight-loss suspension treadmill under simulated Mars gravity (1/3 G) and lunar gravity (1/6 G), and traditional earth gravity (1 G) respectively at three different velocities (3, 7 and 10 km/h). During the exercise, parameters such as stance phase, plantar force, and gait balance in gait cycle were analyzed by using the F-scan insole pressure distribution measurement system. Results At the same velocity during a gait cycle, the contact phase was significantly shorter with the decrease of gravity, but the swing phase was significantly longer (P0.05). The peak and average plantar force, force integrity were significantly reduced with the decrease of gravity. Under normal gravity, the increase of velocity could lead to an obvious increase in peak and average plantar force and an obvious decrease in force integrity. While under simulated lunar and Mars gravity, no significant changes were found in plantar force (P>0.05). Under the three gravities, the ratio of vertical impact was quite different in between (P<0.05), but no significant difference was found in the phase symmetry index. Conclusions As compared to normal gravity environment, parameters benefiting for skeleton and muscle function such as plantar force and contact phase were found to be much smaller under low gravity environment, indicating the necessity of considering these factors when designing countermeasures or exercise prescriptions for space flight so as to sustain the astronaut’s normal function of skeleton and muscle.