40 research outputs found

    Treatment of astigmatism-related amblyopia in 3- to 5-year-old children

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    AbstractBest-corrected acuity was measured for vertical and horizontal gratings and for Lea Symbols® recognition acuity in 3- to 5-year-old children with high astigmatism and in non-astigmatic children. There was significant amblyopia among astigmatic children at baseline. There was no evidence that eyeglass correction of astigmatism resulted in a reduction in amblyopia over a 4-month average treatment duration (although vision in astigmatic children was significantly improved immediately upon eyeglass correction, indicating that eyeglass correction did provide a visual benefit). Treatment outcome results are discussed in terms of both methodological issues and theoretical implications

    Visual Psychophysics and Physiological Optics Longitudinal Change and Stability of Refractive, Keratometric, and Internal Astigmatism in Childhood

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    PURPOSE. To assess longitudinal change in refractive, keratometric, and internal astigmatism in a sample of students from a population with a high prevalence of with-the-rule (WTR) astigmatism and to determine the optical origins of changes in refractive astigmatism. METHODS. A retrospective analysis of longitudinal measurements of right eye refractive and keratometric astigmatism in Tohono O'odham Native American children was conducted. Changes in refractive and keratometric astigmatism per year were compared in a younger cohort (n ¼ 1594, 3 to <11 years old) and an older cohort (n ¼ 648, 11 to <19 years old). Data were analyzed in clinical notation (Cyl) and vector notation (J0, J45). RESULTS. On average, refractive astigmatism (means: 1.19 diopters [D] Cyl, þ0.54 J0, þ0.03 J45) resulted primarily from WTR corneal astigmatism (means: þ0.85 J0, À0.02 J45) and against-the-rule (ATR) internal astigmatism (means: À0.31 J0, þ0.05 J45). Mean longitudinal changes in astigmatism were statistically significant (younger cohort À0.02 D/y Cyl; older cohort þ0.06 D/y Cyl). In the younger cohort, astigmatism decreased with age in low and moderate astigmats (<3.00 D) and increased with age in high astigmats ( ‡3.00 D). In the older cohort, astigmatism increased with age across all levels of astigmatism. Longitudinal changes in keratometric and internal astigmatism were negatively correlated in both cohorts. CONCLUSIONS. Cross-sectional data suggest the presence of a constant ATR contribution from internal astigmatism (0.60 D Cyl) that is close to the 0.50 D ATR constant reported by Javal and others. Highly astigmatic 3-to <11-year-old children and children older than age 11 years show a small (not clinically significant) increase in astigmatism with age. A negative correlation between changes in keratometric astigmatism and internal astigmatism suggests an active compensation that may contribute to the stability of astigmatism in Tohono O'odham children. Keywords: astigmatism, refractive error development, children, Native American R esearch conducted over the past 15 years has yielded a large longitudinal database on refractive development in Tohono O'odham children. There is a high prevalence of astigmatism among elementary school children who are members of this Native American tribe. 1-4 The high prevalence of refractive astigmatism in Tohono O'odham children is present in infancy and persists at least through elementary school. 1,2,4-7 A longitudinal study of corneal astigmatism in 960 Tohono O'odham children aged 6 months through 7 years showed that in early development (6 months to <3 years), astigmatism decreased in children with high astigmatism (À0.37 diopters [D]/y) and remained stable in children with little or no astigmatism (þ0.05 D/y). 7 From age 3 through 7 years, astigmatism decreased in children with both high astigmatism (À0.11 D/y) and low/no astigmatism (À0.03 D/y). 7 A detailed account of changes in astigmatism beyond age 7 years in this population has not yet been reported. However, a recent report on change in spherical equivalent (M) in a longitudinal sample of Tohono O'odham students ages 3 to 18 years showed that rate of change in M with age was significantly greater for children who were hyperopic (M ‡ þ2.00) prior to age 5.5 years, consistent with continued emmetropization into the school years. In addition, higher levels of refractive astigmatism were associated with predicted myopia onset (M À0.75 D) by age 18 years. 9 This relation, specifically the relation between keratometric and refractive (total) astigmatism, was originally described by Javal in 1890 10,11 : Refractive Astigmatism ¼ 1.25(Keratometric Astigmatism) À 0.50 D 3 90. A more recent empirically based modification of Javal's rule suggests that WTR and ATR refractive astigmatism can be predicted by subtracting an ATR constant (0.50 D) from the magnitude of keratometric astigmatism, with little or no adjustment based on magnitude of keratometric astigmatism. 10 Little is known about how the relation between keratometric and internal astigmatism changes with development in childhood. For example, it is not known if magnitude of AT

    Longitudinal assessment of daily activity patterns on weight change after involuntary job loss: the ADAPT study protocol

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    Background: The World Health Organization has identified obesity as one of the most visible and neglected public health problems worldwide. Meta-analytic studies suggest that insufficient sleep increases the risk of developing obesity and related serious medical conditions. Unfortunately, the nationwide average sleep duration has steadily declined over the last two decades with 25% of U.S. adults reporting insufficient sleep. Stress is also an important indirect factor in obesity, and chronic stress and laboratory-induced stress negatively impact sleep. Despite what we know from basic sciences about (a) stress and sleep and (b) sleep and obesity, we know very little about how these factors actually manifest in a natural environment. The Assessing Daily Activity Patterns Through Occupational Transitions (ADAPT) study tests whether sleep disruption plays a key role in the development of obesity for individuals exposed to involuntary job loss, a life event that is often stressful and disrupting to an individual’s daily routine. Methods: This is an 18-month closed, cohort research design examining social rhythms, sleep, dietary intake, energy expenditure, waist circumference, and weight gain over 18 months in individuals who have sustained involuntary job loss. Approximately 332 participants who lost their job within the last 3 months are recruited from flyers within the Arizona Department of Economic Security (AZDES) Unemployment Insurance Administration application packets and other related postings. Multivariate growth curve modeling will be used to investigate the temporal precedence of changes in social rhythms, sleep, and weight gain. Discussion It is hypothesized that: (1) unemployed individuals with less consistent social rhythms and worse sleep will have steeper weight gain trajectories over 18 months than unemployed individuals with stable social rhythms and better sleep; (2) disrupted sleep will mediate the relationship between social rhythm disruption and weight gain; and (3) reemployment will be associated with a reversal in the negative trajectories outlined above. Positive findings will provide support for the development of obesity prevention campaigns targeting sleep and social rhythms in an accessible subgroup of vulnerable individuals

    Minimum Phase Considerations in the Analysis of Sinusoidal Work

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    Computer-Controlled Cycle Ergometer

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    Outcome of asthma and wheezing in the first 6 years of life follow-up through adolescence

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    Rationale: The effect of early life wheezing on respiratory function and continued symptoms through adolescence has not been fully described. Using data from a population-based birth cohort in Tucson, Arizona, we previously described four phenotypes based on the occurrence of wheezing lower respiratory illnesses before age 3 yr and active wheeze at age 6 yr: never wheezers (n = 425), transient early wheezers (n = 164), persistent wheezers (n = 113), and late-onset wheezers (n = 124). Objective: We sought to determine the prognosis for these phenotypes, with reference to lung function and symptoms, through adolescence. Methods: Current wheeze was assessed by questionnaire, lung function was measured by conventional spirometry, and atopy was determined by skin prick tests. Results: The prevalence of atopy and wheeze by age 16 yr was similar for never and transient wheezers and for persistent and late-onset wheezers. Both transient early, and persistent wheezers had significantly lower FEF(25–75) (–259 ml/s, p < 0.001, and –260 ml/s, p = 0.001, respectively), FEV(1) (–75 ml, p = 0.02, and –87 ml, p = 0.03, respectively), and FEV(1):FVC ratio (–1.9%, p = 0.002, and –2.5%, p = 0.001, respectively) through age 16 yr compared with never wheezers. Late-onset wheezers had levels of lung function similar to those of never wheezers through age 16 yr. There was no significant change in lung function among subjects with any of the four phenotypes, relative to their peers, from age 6 to 16 yr. Conclusion: Patterns of wheezing prevalence and levels of lung function are established by age 6 yr and do not appear to change significantly by age 16 yr in children who start having asthmalike symptoms during the preschool years
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