Childhood ethnic differences in ametropia and ocular biometry:the Aston Eye Study

Purpose: To describe the methodology, sampling strategy and preliminary results for the Aston Eye Study (AES), a cross-sectional study to determine the prevalence of refractive error and its associated ocular biometry in a large multi-racial sample of school children from the metropolitan area of Birmingham, England. Methods: A target sample of 1700 children aged 6–7 years and 1200 aged 12–13 years is being selected from Birmingham schools selected randomly with stratification by area deprivation index (a measure of socio-economic status). Schools with pupils predominantly (>70%) from a single race are excluded. Sample size calculations account for the likely participation rate and the clustering of individuals within schools. Procedures involve standardised protocols to allow for comparison with international population-based data. Visual acuity, non-contact ocular biometry (axial length, corneal radius of curvature and anterior chamber depth) and cycloplegic autorefraction are measured in both eyes. Distance and near oculomotor balance, height and weight are also assessed. Questionnaires for parents and older children will allow the influence of environmental factors on refractive error to be examined. Results: Recruitment and data collection are ongoing (currently N = 655). Preliminary cross-sectional data on 213 South Asian, 44 black African Caribbean and 70 white European children aged 6–7 years and 114 South Asian, 40 black African Caribbean and 115 white European children aged 12–13 years found myopia prevalence of 9.4% and 29.4% for the two age groups respectively. A more negative mean spherical equivalent refraction (SER) was observed in older children (-0.21 D vs +0.87 D). Ethnic differences in myopia prevalence are emerging with South Asian children having higher levels than white European children 36.8% vs 18.6% (for the older children). Axial length, corneal radius of curvature and anterior chamber depth were normally distributed, while SER was leptokurtic (p < 0.001) with a slight negative skew. Conclusions: The AES will allow ethnic differences in the ocular characteristics of children from a large metropolitan area of the UK to be examined. The findings to date indicate the emergence of higher levels of myopia by early adolescence in second and third generation British South Asians, compared to white European children. The continuation of the AES will allow the early determinants of these ethnic differences to be studied.

Is subclinical thyroid dysfunction in the elderly associated with depression or cognitive dysfunction?

Background: Widespread use of automated sensitive assays for thyroid hormones and thyroid-stimulating hormone (TSH) has increased identification of mild thyroid dysfunction, especially in elderly patients. The clinical significance of this dysfunction, however, remains uncertain, and associations with cognitive impairment, depression, and anxiety are unconfirmed. Objective: To determine the association between mild thyroid dysfunction and cognition, depression, and anxiety in elderly persons. Design: Cross-sectional study. Associations were explored through mixed-model analyses. Setting: Primary care practices in central England. Patients: 5865 patients 65 years of age or older with no known thyroid disease who were recruited from primary care registers. Measurements: Serum TSH and free thyroxine (T4) were measured. Depression and anxiety were assessed by using the Hospital Anxiety and Depression Scale (HADS), and cognitive functioning was established by using the Middlesex Elderly Assessment of Mental State and the Folstein Mini-Mental State Examination. Comorbid conditions, medication use, and sociodemographic profiles were recorded. Results: 295 patients met the criteria for subclinical thyroid dysfunction (127 were hyperthyroid, and 168 were hypothyroid). After confounding variables were controlled for, statistically significant associations were seen between anxiety (HADS score) and TSH level (P = 0.013) and between cognition and both TSH and free T4 levels. The magnitude of these associations lacked clinical relevance: A 50-mIU/L increase in the TSH level was associated with a 1-point reduction in the HADS anxiety score, and a 1-point increase in the Mini-Mental State Examination score was associated with an increase of 50 mIU/L in the TSH level or 25 pmol/L in the free T4 level. Limitations: Because of the low participation rate, low prevalence of subclinical thyroid dysfunction, and other unidentified recruitment biases, participants may not be representative of the elderly population. Conclusions: After the confounding effects of comorbid conditions and use of medication were controlled for, subclinical thyroid dysfunction was not associated with depression, anxiety, or cognition. © 2006 American College of Physicians.