中国成年人视力损害患病率:北京眼病研究

PURPOSE: To estimate the prevalence and distribution of blindness and low vision in Northern China. DESIGN: Population-based cohort study. METHODS: The Beijing Eye Study included 4438 subjects with an age of 40+ years. Mean age was 56.2± 10.6 years (range,40 to 101 years). RESULTS: Fortythree (1.0% ) individuals had low vision (< 20/60 and ≥ 20/400 best-corrected vision),and 17 (0.4% ) individuals were blind (best-corrected visual acuity in the better-seeing eye < 20/400). Low vision/blindness were significantly associated with age (P < .001),myopic refractive error (P < .001),and level of educational background (P=.035). It was not associated with gender (P=.76) and rural vs urban area (P=.88). CONCLUSIONS: Blindness or low vision affects approximately one in 100 Chinese older than 40 years. An estimated 4.1 million Chinese older than 40 years have low vision,and an estimated 1.6 million Chinese older than 40 years are blind.

二尖瓣修补时行经食管超声心动图利用压力减半时间计算的结果低估了二尖瓣膜面积

Background: Mitral valve repair(MVRr) has become themainstay of surgical treatment for mitral valvular regurgitation. Evaluation of MVRr by intraoperative transesophageal echocardiography(IOE) has been routinely employed to guide the operation. While the main objective of IOE is to assess for residual mitral regurgitation, it is also important to exclude significant mitral stenosis. Utilisation of pressure half-time(PHT) to estimate mitral valve area(MVA) has been shown to be reliable in normal clinical situations. However, in MVRr, the accuracy of MVA calculation by PHT needs to be ascertained. Methods and results: Data from IOE and post-MVRr transthoracic echocardiography(TTE) from the year 1998 to 2002 were analysed and when required, offline PHT measurements were made. The mean time interval between the two echocardiographic examinations was 10.6(1 to 56) weeks. In our 36 cases, the IOE MVA was found to be 2.1± 0.5 cm2, with the corresponding TTE MVA to be 2.7± 1.0 cm2. MVA by PHT with IOE underestimated TTE findings by 0.6± 0.9 cm2(95% CI:-0.85 to-0.24, P=0.001). In 6 patients, the IOE MVA was moderately reduced. Subsequent TTE in these patients showed that the MVA was adequate and was significantly underestimated by IOE in 5 of these patients. In all these cases, IOE underestimated MVA by a margin, which may result in a need to revise the repair. Conclusion: We find that IOE immediately after MVRr tends to underestimate MVA by PHT calculation. The underestimation by IOE may have clinical importance in cases when MVA by IOE is moderately reduced. Therefore, pressure half-time measurement should not be used to assess mitral valve areas during mitral valve repair.

时空谱多维数据格式(MDD)结构与计算机配套系统

遥感观测数据包括了时间、空间、光谱属性等特征在内的多维度信息,为了便于多维度大数据之间互操作和数据分析,作者团队在综合考虑多维大数据特点的基础上,研发了一种将遥感产品涉及的时间、空间、光谱特征等关联成一体的数据格式,命名为"多维数据格式(MDD,Multi-Dimensional Data Format)"。本文论述.mdd数据格式的算法原理,像元、波段、光谱时空特征的排列结构,其中包括由TSB(TemporalSequentialinBand)、TSP(Temporal Sequential in Pixel)、TIB(Temporal Interleaved by Band)、TIP(Temporal Interleaved by Pixel)和TIS(Temporal Interleaved by Spectrum)五种数据存储格式组成的关联组织关系和数据组织结构。为了方便使用该数据格式,作者团队研发了计算机配套软件系统-遥感多维数据格式互操作分析软件系统(Multi-dimensional Analysis of Remote Sensing V1.0,MARS),该软件具有.mdd格式数据的输入、存储、分析、输出及格式转换等功能。此外,该软件也具有图像预处理、光谱分析、遥感数据分类等功能。