Positive correlation between Tono-Pen intraocular pressure and central corneal thickness

OBJECTIVE: To examine the relationship between intraocular pressure (IOP) readings taken by the Tono-Pen tonometer (Mentor O&O, Norwell, MA) and central corneal thickness (CCT). DESIGN: Prospective cross-sectional population study. PARTICIPANTS: There were 651 eyes of 332 healthy subjects. MAIN OUTCOME MEASURES: A questionnaire was given to each subject requesting information on gender, age, race, and other factors that can influence IOP. The IOP then was measured using the Tono-Pen followed by measurements of CCT using an ultrasonic pachymeter. RESULTS: The IOP was found to increase by 2.9 mmHg/100 microns CCT in males and 1.2 mmHg/100 microns in females. For males, CCT was found to be statistically significant in predicting IOP (P < 0.001 in the right and left eyes) and diabetes was of borderline significance (P = 0.012 in the right eye, P = 0.089 in the left eye). For females, CCT was of borderline significance (P = 0.064 in the right eye, P = 0.019 in the left eye). In females, a family history of glaucoma (P = 0.021 in the right eye, P = 0.022 in the left eye) and hypertension (P = 0.010 in the right eye, P = < 0.001 in the left eye) were also significant in the prediction of IOP. Race was found to be a significant predictor of CCT (P < 0.001 in both right and left eyes) for both males and females. CONCLUSION: Clinicians should be aware that, as with the Goldmann applanation tonometer, the Tono-Pen has a systematic error in IOP readings caused by its dependence on CCT. Tono-Pen IOP readings are positively correlated to CCT in males and, to a lesser extent, in females as well. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in the diagnosis and management of disorders in which the CCT or IOP readings are outside normal limits.     

Further data on the characters of Listeria strains

The composition of a minimal medium suitable for the demands of modern genetical work is described. The nutritional requirements of some 15 strains of L. monocytogenes were studied on this medium. DL-6,8-thioctic acid was not essential. The organisms also grew without thiamine but for a convenient colony size this vitamin had to be used. The presence of Fe++, Mg++, and Ca++ ions as well as a low redox potential supplied by thioglycollate was necessary. There was some difference in the amino acid requirements of the strains. The most common demand was for leucine, iso-leucine, valine, and cysteine. The serotype, agglutinability, hemolytic effect, virulence, and nutritional requirements of the Listeria were compared. It seems that these properties are not consistently linked. Two 'EMS' mutants were also studied. The arginine, glutamine, and methionine metabolism of the auxotrophic mutant 025/4/4 was damaged and its virulence was lost. Data connected with the virulence markers of Listeria are discussed.     

Further evidence for feature correlations in semantic memory.

The role of feature correlations in semantic memory is a central issue in conceptual representation. In 2 versions of the feature verification task, participants were faster to verify that a feature () is part of a concept (grapefruit) if it is strongly rather than weakly intercorrelated with the other features of that concept. Contrasting interactions between feature correlations and stimulus onset asynchrony were found when the concept versus the feature was presented first. An attractor network model of word meaning that naturally learns and uses feature correlations predicted those interactions. This research provides further evidence that semantic memory includes implicitly learned statistical knowledge of feature relationships, in contrast to theories such as spreading activation networks, in which feature correlations play no role. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparing correlations based on individual-level and aggregated data.

Researchers are often interested in comparing correlations between variables at different levels of analysis (e.g., individual and organizational) to determine if the same relationship holds across the levels. A special situation emerges when correlations at higher levels are based on aggregated data. This article contains an analysis of the nature of the relationship between correlations based on individual-level data and correlations based on aggregated data from individuals. In particular, the conditions under which differences between individual correlations and correlations based on aggregates represent statistical artifacts or meaningful differences are explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Central corneal thickness and intraocular pressure in a Mongolian population

OBJECTIVE: The purpose of the study was to quantify the variation of central corneal thickness (CCT) in an east Asian population and to examine its relationship to estimates of intraocular pressure (IOP) made with an applanation tonometer. DESIGN: The study design was a cross-sectional, population-based survey. PARTICIPANTS: One thousand two-hundred forty-two residents of H?vsg?l Province, Mongolia, 10 to 87 years of age participated. MAIN OUTCOME MEASURES: The CCT was measured using an optical pachymeter in all subjects. The IOP was measured using a, Goldmann-type applanation tonometer in subjects 40 years of age and older. RESULTS: There was a highly significant decrease in CCT with age: 5 microns/decade in men and 6 microns/decade in women (both, P < 0.0001). A highly significant positive correlation was identified between IOP and CCT. Linear regression analysis suggests that between the ages of 40 and 80 years, an increase in CCT of 10 microns is associated with an increase in IOP measurements of 0.18 mmHg in right eyes (95% confidence interval, 0.12-0.25) and 0.24 mmHg in left eyes (95% confidence interval, 0.17-0.31). The authors calculate that interindividual differences in CCT may produce a difference in measured IOP of between 2.3 and 3.1 mmHg. CONCLUSIONS: Variation in CCT is a significant source of variation in IOP measurements between individuals. The authors suggest that measurement of corneal thickness should be considered when assessing IOP as a risk factor for glaucoma in east Asians.     

Posterior corneal surface topographic changes after laser in situ keratomileusis are related to residual corneal bed thickness

OBJECTIVE: To determine whether ectasia after laser in situ keratomileusis (LASIK) is related to residual corneal bed thickness. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Thirty-two eyes of 16 patients with refractive errors of -4.00 to -18.00 diopters were examined. INTERVENTION: LASIK was performed. The topography of the posterior corneal surface was examined with the Orbscan slit scanning corneal topography/pachymetry system. MAIN OUTCOME MEASURES: The difference in the elevation of posterior corneal surface regarding the best-fit sphere was measured. RESULTS: After surgery, mean bulge of 17.2 +/- 7.2 microns was found in eyes with residual corneal bed of 250 microns or greater, whereas 41.0 +/- 22.1 microns was seen in eyes with bed thickness less than 250 microns (t = 4.29; P = 0.000). CONCLUSION: Posterior corneal bulge is correlated with the residual corneal bed thickness. The risk of ectasia may be increased if the residual corneal bed is thinner than 250 microns.     

Comparison of central corneal endothelial cell numbers with peripheral areas

Using a specific fixation device on a group of patients, we compared corneal endothelial cell count areas above, below, and temporally with the central corneal cell counts. Although younger patients, the central cornea mirrored the peripheral cell counts; peripheral counts were similar in each group. Patients with intraocular lenses had fewer cells than patients with uneventful cataract extraction, and the central cornea was representative in the cataract group. Only in the intraocular lens group was there a small difference between central endothelial cell counts and the temporal and inferior cell counts; but even this difference was significantly less than that seen in patients with intracapsular cataract extraction.     

中等厚度连铸板坯中心宏观偏析特性研究

精确了解连铸板坯偏析分布的特征,对连铸的工艺控制以及提高连铸坯检测效率有很好的指导价值。本文采用金属原位分析仪对中等厚度连铸板坯的宏观偏析特征进行了系统地研究。结果表明:铸坯中心偏析成岛状出现在中心线附近,且彼此孤立,中心成分起伏波动大;最大偏析的出现位置有一定的偶然性,有时偏离中心线;正偏析元素在整个中心等轴状晶区域内平均含量比较高,波动剧烈,但偏析程度变化在该区域没有明显的趋势;柱状晶组织向等轴状晶的过渡区为严重偏析的高发区域,不同枝晶的生长方式使该区域出现重偏析带。     

The formation of stereotypic beliefs: Further evidence for distinctiveness-based illusory correlations.

Investigated the processes underlying illusory correlations based on the co-occurrence of infrequent stimulus events in 2 experiments with 104 undergraduates. In Exp I, 4 groups of 20 Ss were assigned to 1 of 4 conditions. Group 1 read a series of stimulus sentences describing desirable and undesirable behaviors performed by members of Groups A and B. Group 2 read the same sentences but had a different order of presentation. Group 3 read the sentences and were shown a frequency table summarizing the information they had just read. Group 4 was given only the summary table showing the frequency distribution of desirable and undesirable behaviors for Groups A and B and asked to imagine that they had read sentences. Analysis of Ss' ratings showed that the bias producing the illusory correlation occurred during the encoding of serially presented stimulus items and was not due to biased integration of information at the time of judgment. In Exp II, 24 Ss were used to assess recall of stimulus information. Results show that Ss recalled a higher proportion of items representing the co-occurrence of distinctive stimuli than of the other categories of items. The central role of these items in establishing the illusory correlations was further substantiated by correlational evidence. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further analysis of dendritic growth data for succinonitrile

Data reported by Glicksman, Schaefer and Ayers¹ on dendritic growth kinetics in undercooled succinotrile have been reanalyzed using the Trivedi model of dendritic growth, after relaxation of the arbitrary requirement that the dendrite grows with a tip radius, ρ max, that gives the maximum velocity, V_max The experimental results, for both tip radius and growth velocity, fit the Trivedi model with a tip radius some 2 to 4 times greater than ρ_max. The tip radius adopted by a dendrite growing in liquid at a given undercooling, appears to correspond to the radius which gives relative instability of a sphere growing in liquid with the same undercooling. The experimental results also give qualitative support to the model recently proposed by Cantor and Vogel for the influence of fluid flow on dendritic growth.     

Central corneal thickness in normal, glaucomatous, and ocular hypertensive eyes

We should recognize that we have a responsibility to people who live outside our own borders, and view ourselves as part of the global community. Looking at China we are faced with ethical dilemmas which require consideration. First, there is the ethical dilemma of business versus health. The opening and development of the tobacco business in China, which includes vigorous marketing, is considered against the health consequences of tobacco use which is estimated to cost 600,000 lives annually in China, rising to 2 million by 2,025 without effective tobacco control programmes. A second ethical dilemma is employment versus impoverishment, in which the opportunities for work in the tobacco industry are considered against a background of malnutrition caused in part by a proportion of household budgets used to buy tobacco, and the erosion of the land, as trees are used to produce tobacco. Gains have already been made in tobacco control in China, with the way open for much development in the future.     

Further data on key influencers of occupational expectation among minority youth.

Reports the relative frequency with which each of 9 specific "key figures" was reported by 73 Puerto Rican, 211 black, and 200 white high school females from "working-class" families to have exercised the principal influence over their selection of occupations they expected to hold as adults. Rank-order coefficients reveal the least similarity in citation of key figures between white and Puerto Rican Ss and virtually no difference between black and Puerto Rican Ss or between black and white Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved algorithm for statistical batch-by-batch analysis of corneal topographic data

Congenital parvovirus infection was diagnosed in two liveborn premature infants born at 24 and 35 weeks of gestational age. The illnesses were associated with placentomegaly, petechial rash, edema, hepatomegaly, anemia and thrombocytopenia, respiratory insufficiency, and death at 5 and 6 days of age. The syndromes exhibited by these cases shared common but nonspecific features with other life-threatening congenital infections. Serological studies in one case supported the diagnosis of parvoviral infection. Postmortem examination of both revealed nuclear inclusions in erythroid precursor cells characteristic of parvovirus infection. Use of the polymerase chain reaction confirmed the presence of parvovirus DNA in one of the cases. Intrauterine parvovirus B19 infection is most commonly associated with hydrops fetalis, "transient" hydrops, or a favorable outcome in infants found to be viremic after birth. These and previously reported examples of congenital B19 disease exemplify an exceptional form of human parvovirus infection.     

Estimating correlations from epidemiological data in the presence of measurement error

Analysis of a major multi-site epidemiologic study of heart disease has required estimation of the pairwise correlation of several measurements across subpopulations. Because the measurements from each subpopulation were subject to sampling variability, the Pearson product moment estimator of these correlations produces biased estimates. This paper proposes a model that takes into account within and between sub-population variation, provides algorithms for obtaining maximum likelihood estimates of these correlations and discusses several approaches for obtaining interval estimates.     

Hypnotizability and phobic behavior: Further supporting data.

20 21–59 yr old women who were phobic to snakes, spiders, or rats were individually evaluated for hypnotic susceptibility, using the standard audiotaped version of the Harvard Group Scale of Hypnotic Susceptibility, Form A. Consistent with the findings of earlier studies using similar methods for measuring hypnotizability but not with a recent study using the Hypnotic Induction Profile (HIP), 55% of the present sample was found to be highly responsive to hypnosis. An item analysis comparing item pass percentages for the phobic Ss with item difficulties obtained from a normative sample of 357 female college students indicated that the 2 samples were significantly correlated. The discrepancy between the findings using standard measures of hypnotizability and studies using HIP is discussed. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Further observational data on the behavioral and social world of institutions for the aged.

This study is an extension of previous observational work on the social ecology of dependence and independence in the institutionalized elderly. Observations of everyday, naturally occurring interactions between elderly residents of two different long-term institutions and their social partners were extended such that, aside from the identification of type of behavior, the dyadic form and continuity of each behavior was specified. The following were among the major results: (a) Previously found interaction patterns between elderly residents and their social partners, replicated in both a nursing home and a home for the chronically ill, supported the notion of discrepant social ecologies for dependent versus independent behaviors of residents; (b) specification of each behavioral act as to its dyadic form underscored the fact that the interactions were controlled largely by social partners and not by the elderly residents; (c) coding continuity or discontinuity of behavior suggested that independent behaviors were maintained by chaining; and (d) elderly residents in the home for the chronically ill evinced, as expected, more dependence-related behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)