【文章內(nèi)容簡介】 lamp. Fig. 1.Image of the tear meniscus height captured by a camera attached to the slitlamp.View Within Article. Statistical analysisThe distribution of values and repeatability of three consecutive measures of the TMH at the first study visit were assessed with the coefficient of skewness and the mean standard deviation (.) of repeated measures, respectively. The bias between the two measuring techniques and repeatability between study visits for each technique (. mean difference, ., and 95% confidence limits) were calculated and presented graphically [29]. Comparisons and correlations between measures were performed using paired twotailed ttests and the Pearson39。s product moment correlation coefficient, respectively. Data for the right eye only were used to avoid the confounding effect of using nonindependent data from both eyes [30]. The level of statistical significance was taken as 5%.3. ResultsA mean177。. value of TMH of 177。 (range –mm, median mm) and 177。mm (range –mm, median mm) was found with the image capture and graticule techniques, respectively, at the first study visit (Fig. 2). A lower coefficient of skewness was found with the image capture measures () pared to the graticule measures () at the first visit. The repeatability of three consecutive measures at the first visit was and mm for the graticule and image capture measures, respectively. TMH, as measured with the image capture technique, was significantly longer (by approximately 177。mm, p=) than that measured with the graticule technique (Fig. 3). The image capture technique could be expected to read approximately as much as above or below the subjective technique. There was no significant bias between the two methods of measurement for the whole range of TMH values evident in this study. Both measuring techniques were highly correlated (r=, p). Repeatability of the TMH measurements taken at the two study visits showed that graticule measures were significantly different (177。mm, p=) and highly correlated (r=, p), whereas image capture measures were similar (177。mm, p=), but also highly correlated (r=, p) (Fig. 4).Fig. 2.Histogram to show the distribution of the graticule and image capture measures of the lower tear meniscus height from the 59 right eyes evaluated. Fig. 2.Histogram to show the distribution of the graticule and image capture measures of the lower tear meniscus height from the 59 right eyes evaluated.View Within ArticleFig. 3.Differences between image capture and graticule measures of the lower tear meniscus height (TMH). Fig. 3.Differences between image capture and graticule measures of the lower tear meniscus height (TMH).Fig. 4.Repeatability of the graticule and image capture measures of the lower tear meniscus height (TMH) between the two study visits. Fig. 4.Repeatability of the graticule and image capture measures of the lower tear meniscus height (TMH) between the two study visits.View Within Article4. DiscussionConsistent with previous studies, the values of TMH found in this study were positively skewed for both the graticule and image capture techniques [4] and [12]. In addition, lower mean values of the TMH were found pared to previous studies (Table 1). However, there are a number of reports which, although slightly higher on average, have shown similar values to the TMH values reported here [8], [11], [12], [18] and [19]. Most subjects employed in this study were normal silicone hydrogel contact lens wearers (76%) and a previous study has shown lower values of TMH in silicone hydrogel lens wearers pared to normal noncontact lens wearers [6]. Special care was taken to ensure that subjects maintained primary eye gaze during the measurement of the TMH as it was noted prior to the study that when subjects were asked to look upwards the height of the tear meniscus approximately doubled, and when subjects were looking nasally, about twothirds of the subjects showed higher values of the TMH than when they were maintaining primary eye gaze. Although some studies have measured TMH while subjects were maintaining primary eye gaze [12], [13], [15] and [17], the extent to which others studies have contr