Variability of the Schirmer tear test values in a normal Arab population

Background: As in many parts of the world, the Schirmer tear test is the main test used by optometrists in Saudi Arabia for assessing adequacy of tear production. Variability of the test has been reported in different ethnic groups but not in Arabs. This paper looks at the mean and repeatability of the values obtained by the Schirmer test in a normal Arab population Method: The test was performed on the right eyes of 23 young adult Saudi male subjects at five visits over two weeks. Result: Results showed that for each subject the test values were not repeatable, varying widely over the period of evaluation. The mean value was estimated at 10.6 mm and the 95 per cent confidence limits were 7.9 and 13.3 mm. It was also established that the greater the amount of tears, the greater the variability. Conclusion: This study supports the claim that the Schirmer test is not repeatable and hence is unreliable. Therefore, caution should be exercised in employing it for clinical diagnosis. (Clin Exp Optom 1995; 78: 5: 190–193)     

Evaluation of the epidermal refractive index measured by optical coherence tomography

BACKGROUND/AIMS: It has recently been proposed that the refractive index (RI) measured by means of optical coherence tomography (OCT) may be a valid measure for hydration of skin. In this pilot study, using OCT in vivo, we aimed to investigate the interday variability of RI measurements and acute changes of RI following the application of a moisturizer. METHODS: Twenty healthy Caucasian volunteers were investigated on their forearms using a commercially available OCT system (SkinDex 300, ISIS optronics GmbH, Mannheim, Germany) fitted with an integrated algorithm for the evaluation of the RI. The interday repeatability of the OCT method was determined performing symmetrical measurements on both forearms on day 1, 5, 9, and 13. In order to investigate the acute effect of a moisturizer on RI, OCT assessments were performed before and 10 min after the application of an aqueous lotion with a lipophilic phase. As a control, the contralateral site was investigated in the same way, except for the use of distilled water instead of the lotion. RESULTS: Assessments of interday variability revealed insignificant (P>0.05) variances between the four measurement times as expressed in very small repeatability coefficients (right arm: 0.039; left arm 0.053) and small coefficients of variance (right arm: 1.02%; left arm: 1.38%). With regard to the RIs measured over time, we could not observe significant (P>0.05) differences between the two symmetrical anatomic sites (mean+/-SD of RI: 1.3893+/-0.0142 (right arm); 1.3875+/-0.0192 (left arm)). The acute effect of the moisturizer was indicated by a significant decrease of the RI 5 min after the application of the lotion (1.399+/-0.01 vs. 1.387+/-0.02; difference between means: 0.012; P=0.033; 95% confidence interval: 0.001-0.0023). However the control site treated with distilled water did not show significant differences between the two measurement times (1.387+/-0.013 vs. 1.391+/-0.023; difference between means: -0.004; P=0.57; 95% confidence interval: -0.019-0.011). CONCLUSIONS: In this pilot study, we have demonstrated that RI evaluation via OCT is a promising technique that may be used for the assessment of skin hydration in vivo. However, the direct comparison of OCT with standard methods, ideally such as nuclear magnetic resonance spectroscopy, is necessary.     

Repeatability of the C‐100 colour vision test

Background: The C‐100 colour vision test has been shown to have a high validity for diagnosing the type of red‐green colour vision defect, however, there is little information on the repeatability of the test. This study examines the repeatability of the C‐100 in classifying the colour vision defect as either protan or deutan. Methods: The C‐100 was administered on two occasions to 58 subjects with congenital red‐green colour vision defects: The sessions were separated by a minimum period of 10 days. Results: The repeatability of the C‐100 was high with a kappa coefficient of agreement for diagnosis of 0.96. The few discrepancies were misclassifying protans as deutans. Conclusion: The C‐100 is a highly repeatable test in terms of separating protans from deutans. However, if a discrepancy occurs, it is more likely to be a protan misclassified as a deutan rather than vice versa.     

圆锥角膜快速跨上皮交联手术前后Corvis ST参数的重复性及差异性

目的:评估圆锥角膜快速跨上皮交联手术前以及术后1mo Corvis ST参数的重复性及差异性。方法:研究纳入了30例30眼圆锥角膜患者进行分析。圆锥角膜患者术前和术后1mo分别进行三次Corvis ST重复测量。采用组内相关系数(ICC)、克伦巴赫alpha系数(Cronbach'α)、可重复性系数(RC)和变异系数(CV)评估Corvis ST参数的可重复性。采用配对t检验或Wilcoxon秩和检验评估术前与术后Corvis ST参数的差异。结果:术前39个Corvis ST参数中,26个(66.67%)参数重复性较好,6个(15.38%)参数重复性中等,7个(17.95%)参数的重复性较差。交联术后1mo,34个(87.18%)参数的重复性较好,3个(7.69%)参数重复性中等,2个(5.13%)参数的重复性较差。与术前相比,交联术后1mo圆锥角膜患者的眼压、生物力学校正眼压、第一次压平时间、曲率半径、第一次压平时的形变幅度、最大压陷偏离长度、角膜硬度参数值增加;而陡峭曲率、平坦曲率、平均曲率、第二次压平时间、2 mm最大形变幅度比值和综合半径值降低(均P<0.05)。结论:交联手术前和术后1mo Corvis ST参数均具有较好的可重复性,术后1mo圆锥角膜患者的角膜硬度较术前增加。     

18F-FDG PET/CT代谢的可重复性研究进展

18F-脱氧葡萄糖(18F-FDG)PET／CT在恶性肿瘤的早期诊断、临床分期、疗效评价、监测复发及肿瘤放疗靶区定位中具有重要价值。为了使PET/CT能够更准确地进行恶性肿瘤的疗效评价,18F-FDG PET／CT代谢的可重复性研究显得尤为重要。本文就传统临床代谢参数值标准化摄取值（SUV）、代谢活性肿瘤体积（MATV）、总病灶糖酵解（TLG）、肿瘤与肝脏比率（TLR）、肿瘤与血液比率(SUR)及近年新兴的PET图像纹理分析等方面的可重复性研究进行概述。     

Autoacuity Test与标准对数视力表用于儿童视力测定的比较

 【目的】比较一种计算机视力测试软件Autoacuity Test和标准对数视力表之间的一致性和重复性,初步探讨Autoacuity Test临床应用的可行性。【方法】对41名视功能正常儿童（8.4 ± 1.8岁）和25名弱视儿童（8.0 ± 2.2岁）分别使用标准对数视力表和Autoacuity Test两种方法进行视力测试。30min后重新对其进行测试。以Autoacuity Test与标准对数视力表检查结果的一致性限度的评价其准确性,以测试-再测试的重复系数及配对T检验评价其重复性。【结果】视功能正常儿童的Autoacuity Test与标准对数视力间的一致性限度为0.16 对数单位;弱视儿童为0.31对数单位。正常儿童两种方法各自的测试-再测试结果间差异均无统计学意义（P>0.05）。弱视儿童标准对数视力表测试-再测试结果间差异无统计学意义,Autoacuity再次测试视力检查结果较初次测试有所提高（P<0.05）。【结论】Autoacuity Test与标准对数视力表两种检查方法在视功能正常儿童中一致性较好,在弱视儿童中一致性稍差,两者重复性相近。Autoacuity是一种可取的儿童视力测试方法。     

Reproducibility of Echocardiograph‐Derived Multilevel Left Ventricular Apical Twist Mechanics

Left ventricular (LV) twist mechanics are routinely assessed via echocardiography in clinical and research trials investigating the function of obliquely oriented myocardial fibers. However, echocardiograph‐derived measures of LV twist may be compromised by nonstandardized acquisition of the apical image. This study examined the reproducibility of echocardiograph‐derived parameters of apical twist mechanics at multiple levels of the apical myocardium. Two sets of 2D LV parasternal short‐axis images were obtained in 30 healthy subjects (24 men; 19–57 year) via echocardiography. Images were acquired immediately distal to the papillary muscles (apical image 1), immediately above the point of LV cavity obliteration at end systole (apical image 3), and midway between apical image 1 and apical image 3 (apical image 2). Repeat scans were performed within 1 hour, and twist mechanics (rotation and rotation rate) were calculated via frame‐by‐frame tracking of natural acoustic echocardiographic markers (speckle tracking). The magnitude of apical rotation increased progressively toward the apex (apical image 1: 4.2 ± 2.1°, apical image 2: 7.2 ± 3.9°, apical image 3: 11.8 ± 4.6°). apical images 1, 2, and 3 each had moderate to good correlations between repeat scans (ICC: 0.531–0.856). When apical images 1, 2, and 3 were averaged, rotation was 7.7 ± 2.7° and between‐scan correlation was excellent (ICC: 0.910). Similar results were observed for systolic and diastolic rotation rates. Averaging multiple standardized apical images, tending progressively toward the apex, generated the most reproducible rotation indices and may be optimal for the assessment of LV twist mechanics across therapeutic, interventional, and research studies; however, care should be taken given the influence of acquisition level on the magnitude of apical rotation.     

Repeatability of pleural adenosine deaminase measurements in diagnostic evaluation of pleural effusions

Background

A follow‐up thoracentesis is proposed in suspected atypical tuberculosis cases. The study aimed to define the variability of pleural ADA values across repeated thoracenteses in different types of pleural effusions (PEs) and to evaluate whether ADA variance, in regard to the cutoff value of 40 U/L, affected final diagnosis.

Methods

A total of 131 patients with PEs of various etiologies underwent three repeated thoracenteses. ADA values were subsequently estimated.

Results

82% and 55% of patients had greater than 10% and 20% deviation from the highest ADA value, respectively. From those patients who had a variance of 20%, 36% had only increasing ADA values, while 19% had only decreasing values. Considering the cutoff value of 40 U/L, only in two cases, ADA decreased below this threshold, which concerned a man with tuberculous pleurisy and a woman with lymphoma both in the course of treatment. Furthermore, only in two cases with rising values, ADA finally exceeded the cutoff limit, which concerned a man with rheumatoid pleurisy and a man with tuberculous pleurisy. Surprisingly, malignant PEs (MPEs) showed a higher percentage of increasing values compared to all other exudates that did not, however, exceed the threshold.

Conclusion

The determination of pleural ADA levels is a reproducible method for rapid tuberculosis diagnosis. The detected measurement deviations do not appear to affect final diagnosis. In specific situations, repeated ADA measurements may be valuable in directing further diagnostic evaluation. More investigation is needed to elucidate the possible prognostic significance of the increasing trend in ADA values in MPEs.