偏心摄影视力筛选仪球镜检测用可调式液体模拟眼设计

设计了一种在医疗器械视力筛选仪型式检验时用来检测不同球镜屈光度指标的液体测试模拟眼。这种液体测试模拟眼设计由透镜、腔体、仿视网膜活塞3部分组成。通过利用几何光学原理和人眼视网膜光学散射效应,计算分析了所设计的可调式液体模拟眼调节位移与球镜度的关系。所设计的液体测试模拟眼可用于视力筛选仪、电脑验光仪及其他基于摄影原理验光设备的球镜度测量等。     

弥散斑验光仪的设计

目的 利用人眼屈光弥散斑原理,设计一款使用方便、性能稳定的验光仪.方法 根据理论分析和Zemax软件模拟,搭建弥散斑验光仪光路,设计计算参数;在临床上初步收集近视,散光患者的检查结果,并和温州医学院附属眼视光医院的验光结果进行比较.结果 Zemax模型眼仿真,系统变量分析和临床试用结果表明,弥散斑验光仪原理可靠,性能稳...     

手持自动验光仪与视网膜检影在临床工作中的应用

目的:进一步了解自动验光仪在日常工作中的运用价值。方法:对281例(562眼)2~12岁患儿涂用1%阿托品眼膏麻痹睫状肌后,进行Nikon Retinomax K-Plus(手持自动验光仪验光及视网膜检影。结果:自动验光仪验光及视网膜检影的结果呈高度正相关(r=0.981),二者的平均差值小于0.25D,自动验光仪验光的结果比视网膜检影结果小一些。结论:Ni-kon Retinomax K-Plus(手持自动验光仪与视网膜检影在睫状肌麻痹下检出的屈光结果具有相当高的一致性,在儿童预防保健工作中使用该仪器进行大面积的屈光普查和流行病学调查有很好的实用价值。     

视力筛查仪应用于儿童眼保健中的价值观察

目的：研究视力筛查仪应用于儿童眼保健中的价值。方法：选取本院2020年3月～2021年3月接收的180例需进行健康体检儿童,共计360只眼,所有儿童均需接受阿托品散瞳检影验光检查与视力筛查仪检查,并将阿托品散瞳检影验光检查作为金标准,对比两种检查方式的差异性与优异性。结果：利用视力筛查仪在进行视力检查时屈光异常检出率虽低于阿托品散瞳检影验光检查术,但P>0.05。阿托品散瞳检影验光检查术与视力筛查术在4～6岁年龄段屈光异常检出率均明显高于2～4岁与6月～2岁,P<0.05。结论：视力筛查仪应用于儿童眼保健中的价值较为显著。因此,可将视力筛查仪推广至儿童眼保健检查中。     

中小学生眼屈光不正筛查技术和方法探析

目的探讨应用计算机自动验光仪在大规模学生体检过程中进行眼屈光不正筛查的方法,为视力不良的群防群治提供依据。方法随机抽取到北京眼卫生近视弱视防治研究中心进行视力检查的北京市中小学生573名为对象,按不同散瞳药、不同性别、不同年龄分段对散瞳前后的结果做多因素析因设计方差分析。结果散瞳前的屈光度不能真实反映学生的眼屈光状态。美多利散瞳药的散瞳效果与赛克罗奇散瞳药的散瞳效果是相同的,美多利散瞳后计算机自动验光结果是客观准确的。散瞳前计算机自动验光的结果与散瞳后验光结果存在线性关系。结论应用计算机自动验光仪适宜学生大规模体检过程中进行屈光不正筛查。     

儿童睫状肌麻痹后电脑验光与检影验光的对照研究

目的:寻求一种简单、快速而准确的儿童屈光检查方法。方法:1％硫酸阿托品眼膏涂眼3 d,3次／d后,用Topon8100-A型自动电脑验光仪验光及视网膜检影验光,比较182例(364眼)的验光结果。结果:两种方法的球镜值和柱镜值呈高度相关性(rs=0.963,rc=0.931)。两种方法所测柱镜轴向差别较大,柱镜轴向符合率与柱镜值大小有关。柱镜值越大,其轴向符合率越高。柱镜值≥±1.75 DC,其轴差平均4.3°。结论:在合理使用睫状肌麻痹剂后,自动电脑验光仪检测结果与视网膜检影验光结果高度相关,可作为试镜起点,但要注意在复光试镜中核实轴向。     

屈光不正托吡卡胺散瞳前后计算机验光对比分析

目的探讨10~25岁屈光不正者原瞳计算机验光结果的准确性,为开展对计算机验光的方法研究提供参考依据。方法应用拓普康A 7000计算机验光仪,对屈光不正400例(800只眼)进行托吡卡胺散瞳前后验光结果对比分析。结果睫状肌麻痹前后验光对比结果:球镜差值≤0.50 DS的有688只眼,占86.0%;柱镜差值≤0.50 DC的有586只眼,占94.5%;柱镜轴向偏差小于10°者有591只眼,占95.3%。结论原瞳孔下计算机验光值可以作为屈光检查的起点,再根据配镜原则进行人工验光试片后予以配镜处方。     

儿童睫状肌麻痹后电脑验光与检影验光的对照研究

目的:寻求一种简单、快速而准确的儿童屈光检查方法.方法:1%硫酸阿托品眼膏涂眼3 d,3次/d后,用Topon8100-A型自动电脑验光仪验光及视网膜检影验光,比较182例(364眼)的验光结果.结果:两种方法的球镜值和柱镜值呈高度相关性(rs=0.963,ro=0.931).两种方法所测柱镜轴向差别较大,柱镜轴向符合率与柱镜值大小有关.柱镜值越大,其轴向符合率越高.柱镜值≥±1.75 DC,其轴差平均4.3°.结论:在合理使用睫状肌麻痹剂后,自动电脑验光仪检测结果与视网膜检影验光结果高度相关,可作为试镜起点,但要注意在复光试镜中核实轴向.     

手持式视力筛查仪和自动电脑验光仪在青少年屈光检查中的应用

目的：分析青少年屈光检查中应用手持式视力筛查仪和自动电脑验光仪的效果差异。方法：列入2018年1月～2021年1月本院验光配镜的青少年60例（120眼）,通过全盲抓阄法将其分为手持组及电脑组,每组均30例（60眼）。手持组青少年接受手持式视力筛查仪检查,电脑组青少年接受自动电脑验光仪检查,此外两组青少年共同接受视网膜检影验光检查。将手持式与自动电脑检查散瞳前后结果分别与视网膜检影验光检查的相关数据参数进行对比。结果：散瞳前手持组青少年的球镜值与散瞳后差异显著;散瞳前电脑组青少年的球镜值与散瞳后差异显著;散瞳前电脑组的球镜值及柱镜值与视网膜检影验光检查数据结果差异显著;散瞳后手持组的球镜值及电脑组的柱镜值与视网膜检影验光检查数据结果差异显著,比对数据具备差异性统计区别（P<0.05）。结论：在自然瞳孔下,手持式视力筛查结果比自动电脑验光检查准确性更高,但在睫状肌麻醉散瞳后,自动电脑验光检查的准确性更高于手持式视力筛查,二者各有优点,均可作为试镜的参考依据。     

Suresight手持式自动验光仪在儿童眼保健中的应用分析

[目的] Suresight手持式自动验光仪在儿童眼保健中的应用分析,达到早期防治弱视的目的. [方法]门诊入园体检的学龄前儿童807人,采用美国伟仑公司生产的Suresight手持式自动验光仪进行视力筛查. [结果]发现异常率达27.32%,2.5～4岁年龄别之间筛查异常率差异无显著性,不同性别之间筛查异常率差异无显著性.筛查异常较多表现为散光,其次为远视. [结论] 通过Suresight手持式自动验光仪的结果大致了解儿童的屈光状态,为临床进一步的检查和眼保健提供参考,达到早期发现弱视的目的,对眼保健工作具有重要的指导意义.     

混合线性模型在临床试验中重复测量资料的应用

目的：探讨混合线性模型在临床试验重复测量资料分析中的应用。方法：利用混合线性模型分析结果指标为定量资料的重复测量资料，通过参数和标准误的估计得出统计学结论。结果：对于临床试验重复测量资料，混合线性模型能有效的考虑数据相关性，处理有缺失值的资料，可以获得组别、时间及有无交互作用的结论。结论：采用混合线性模型对临床试验重复测量资料进行统计分析，可以更客观的进行药物疗效评价。     

A bayesian approach to logistic regression models having measurement error following a mixture distribution

To estimate the parameters in a logistic regression model when the predictors are subject to random or systematic measurement error, we take a Bayesian approach and average the true logistic probability over the conditional posterior distribution of the true value of the predictor given its observed value. We allow this posterior distribution to consist of a mixture when the measurement error distribution changes form with observed exposure. We apply the method to study the risk of alcohol consumption on breast cancer using the Nurses Health Study data. We estimate measurement error from a small subsample where we compare true with reported consumption. Some of the self-reported non-drinkers truly do not drink. The resulting risk estimates differ sharply from those computed by standard logistic regression that ignores measurement error.     

Evaluating the incremental value of new biomarkers with integrated discrimination improvement

The integrated discrimination improvement (IDI) index is a popular tool for evaluating the capacity of a marker to predict a binary outcome of interest. Recent reports have proposed that the IDI is more sensitive than other metrics for identifying useful predictive markers. In this article, the authors use simulated data sets and theoretical analysis to investigate the statistical properties of the IDI. The authors consider the common situation in which a risk model is fitted to a data set with and without the new, candidate predictor(s). Results demonstrate that the published method of estimating the standard error of an IDI estimate tends to underestimate the error. The z test proposed in the literature for IDI-based testing of a new biomarker is not valid, because the null distribution of the test statistic is not standard normal, even in large samples. If a test for the incremental value of a marker is desired, the authors recommend the test based on the model. For investigators who find the IDI to be a useful measure, bootstrap methods may offer a reasonable option for inference when evaluating new predictors, as long as the added predictive capacity is large.     

Meta-analysis of diagnostic tests with imperfect reference standards.

We present a method to estimate the summary receiver operating characteristic (SROC) curve for combining information on a diagnostic test from several different studies. Unlike previous methods that assume the reference standard to be error free, our approach allows for the possibility of errors in the reference standard, through use of a latent class model. The model provides estimates of the sensitivity and specificity of the diagnostic test and the case prevalence in each study; these parameters can then be used in a meta-analysis, for example, using the regression method proposed by Moses et al., of a measure of test discrimination on a measure of the diagnostic threshold, to fit the SROC. The method is illustrated with an example on Pap smears that shows how adjusting for imperfection in the reference standard typically reduces the scatter of data in the SROC plot, and tends to indicate better performance of the test than otherwise.     

Implications of a new dietary measurement error model for estimation of relative risk: application to four calibration studies.

Food records or 24-hour recalls are currently used to calibrate food frequency questionnaires (FFQs) and to correct disease risks for measurement error. The standard regression calibration approach requires that these reference measures contain only random within-person errors uncorrelated with errors in FFQs. Increasing evidence suggests that records/recalls are likely to be also flawed with systematic person-specific biases, so that for any individual the average of multiple replicate assessments may not converge to her/his true usual nutrient intake. The authors propose a new measurement error model to accommodate person-specific bias in the reference measure and its correlation with systematic error in the FFQ. Sensitivity analysis using calibration data from four studies demonstrates that failure to account for person-specific bias in the reference measure can often lead to substantial underestimation of the relative risk for a nutrient. These results indicate that in the absence of information on the extent of person-specific biases in reference instruments and their relation to biases in FFQs, the adequacy of the standard methods of correcting relative risks for measurement error is in question, as is the interpretation of negative findings from nutritional epidemiology such as failure to detect an important relation between fat intake and breast cancer.     

“标准服务量”在乡镇卫生院效率评价中的应用

目的：测量乡镇卫生院的服务量，评价乡镇卫生院的经济效率和配置效率。方法：采用文献综述法、专家小组讨论法和现场实证法，分析和验证研究结果。结果：构建了“标准服务量”的方法测量乡镇卫生院的服务产出；用标准服务量测量三类地区乡镇卫生院的经济效率和配置效率。其中西部地区的乡镇卫生院的经济效率均值时5．39元／标准服务量，配置效率是0．39，比中部地区和西北地区的乡镇卫生院都好。结论：“标准服务量”方法测量乡镇卫生院的服务产出、经济效率和配置效率简单、易行，评价结果直观、易理解。     

泌尿系结石CT值与结石易碎性关系分析

目的探讨CT是否可以预测泌尿系结石行体外冲击波(ESWL)及钬激光碎石时结石的易碎性。方法随机选择我院2009年3月至2010年6月间收治的泌尿系结石患者,通过钬激光碎石后取石或体外冲击波碎石后自行排出以及开放手术取出的各种不同成分的结石(每种成分20枚,共100枚,都为单纯性结石),测定平均CT值,放入ESWL体外模式行ESWL及钬激光体外模式下行钬激光碎石。结果 100枚结石的平均CT值与两种碎石方法碎石的次数之间存在直线相关关系,ESWL组相关性较高,钬激光组相关性较低。结论结石平均CT值与ESWL碎石次数之间存在正相关关系,根据术前测定的结石平均CT值可以预测行ESWL时的难易程度。由于结石CT值与钬激光碎石时的碎石次数相关关系较低,所以不能预测行钬激光碎石时的难易程度。     

Summarizing the predictive power of a generalized linear model

This paper studies summary measures of the predictive power of a generalized linear model, paying special attention to a generalization of the multiple correlation coefficient from ordinary linear regression. The population value is the correlation between the response and its conditional expectation given the predictors, and the sample value is the correlation between the observed response and the model predicted value. We compare four estimators of the measure in terms of bias, mean squared error and behaviour in the presence of overparameterization. The sample estimator and a jack-knife estimator usually behave adequately, but a cross-validation estimator has a large negative bias with large mean squared error. One can use bootstrap methods to construct confidence intervals for the population value of the correlation measure and to estimate the degree to which a model selection procedure may provide an overly optimistic measure of the actual predictive power.     

Sensitivity of regression calibration to non‐perfect validation data with application to the Norwegian Women and Cancer Study

Measurement error occurs when we observe error‐prone surrogates, rather than true values. It is common in observational studies and especially so in epidemiology, in nutritional epidemiology in particular. Correcting for measurement error has become common, and regression calibration is the most popular way to account for measurement error in continuous covariates. We consider its use in the context where there are validation data, which are used to calibrate the true values given the observed covariates. We allow for the case that the true value itself may not be observed in the validation data, but instead, a so‐called reference measure is observed. The regression calibration method relies on certain assumptions.This paper examines possible biases in regression calibration estimators when some of these assumptions are violated. More specifically, we allow for the fact that (i) the reference measure may not necessarily be an ‘alloyed gold standard’ (i.e., unbiased) for the true value; (ii) there may be correlated random subject effects contributing to the surrogate and reference measures in the validation data; and (iii) the calibration model itself may not be the same in the validation study as in the main study; that is, it is not transportable. We expand on previous work to provide a general result, which characterizes potential bias in the regression calibration estimators as a result of any combination of the violations aforementioned. We then illustrate some of the general results with data from the Norwegian Women and Cancer Study. Copyright © 2015 John Wiley & Sons, Ltd.     

放疗中基于灰度的图像配准算法性能研究

目的：阐述图像配准在放疗中应用的关键问题,对基于灰度的3种配准方法的性能做深入研究,包括均方测度、归一化相关测度以及互信息测度。方法：分析各配准要素的算法原理后,基于C＋＋加以实现,提出使用综合配准误差来评价不同配准算法的性能,并与传统目标配准误差的评价结果作对比。结果：3种测度都能对近模态的图像实施准确的配准,其中互信息测度驱动的配准在配准精度和速度上表现更为稳定,综合配准误差仅为另外两个测度的一半左右。结论：利用综合配准误差得到的评价结果更为客观,互信息测度是放疗中实施配准的较理想测度。