METHODS: Cycloplegic (1% cyclopentolate) autorefraction was performed on 38, 811 children aged 5 and 15 in population-based samples at eight sites in the Refractive Error Study in Children (RESC). Refractions (right eye) were categorized as myopic (≤-0.5 D), emmetropic (>-0.5 to ≤+0.5 D), mildly hyperopic (>+0.5 to ≤+2.0 D and hyperopic (>+2.0 D).
RESULTS: At five sites (Jhapa - rural Nepal, New Delhi - urban India, Mahabubnagar - rural India, Durban - semi-urban South Africa and La Florida - urban Chile), there was <20% myopia by age 15. Mild hyperopia was the most prevalent category at all ages, except for Mahabubnagar where emmetropia became the marginally most prevalent category at ages 14 and 15. At the other sites (Gombak - semi-urban Malaysia, Shunyi - semi-rural China and Guangzhou - urban China), there was substantial (>35%) myopia by age 15. At these sites, mild hyperopia was the most prevalent category during early childhood, and myopia became the predominant category later. In Gombak district and Guangzhou, emmetropia was a minor category at all ages, with myopia increasing as mild hyperopia decreased. In Shunyi district, emmetropia was the most prevalent category over the ages 11-14.
CONCLUSION: Emmetropia was not the predominant outcome for refractive development in children. Instead, populations were predominantly mildly hyperopic or substantial amounts of myopia appeared in them. This suggests that mild hyperopia is the natural state of refractive development in children and that emmetropia during childhood carries the risk of subsequent progression to myopia.
MATERIALS AND METHODS: Pure tone audiometry test was conducted on 263 residents of a rural village who were not exposed to noise. The pack-years of smoking were computed from the subjects' smoking history. The association between pack-years and hearing impairment was assessed. The combined effect of smoking and age on hearing impairment was determined based on prevalence rate ratio.
RESULTS: There was a statistically significant trend in the number of pack-years of smoking and age as risk factors for hearing impairment. The prevalence rates of hearing impairment for nonsmokers aged 40 years and younger, smokers aged 40 years and younger, nonsmokers older than 40 years of age, and smokers older than 40 years of age were 6.9%, 11.9%, 29.7%, and 51.3%, respectively. The prevalence rate ratio for nonsmokers aged 40 years and younger, smokers aged 40 years and younger, nonsmokers older than 40 years of age, and smokers older than 40 years of age (nonsmokers aged 40 years and younger as a reference group) was 1, 1.7, 4.3, and 7.5, respectively. The prevalence rate ratios showed a multiplicative effect of smoking and age on hearing impairment.
CONCLUSION: Age and smoking are risk factors for hearing impairment. It is clear that smoking and age have multiplicative adverse effects on hearing impairment.
METHODS: Muscle fibre angles of lumbar extensor muscles, thoracolumbar curvature and lumbar extensor muscle strength were examined in 26 young (mean age 27.9, SD 5.2) and 26 older (mean age 72.1, SD 5.9) participants. Pearson's correlation was employed to determine the association among lumbar extensor muscle fibre angle, thoracolumbar curvature, age, gender and lumbar extensor muscle strength. Multiple stepwise linear regression analysis was used to identify significant determinants of lumbar extensor muscle strength.
RESULTS: The results demonstrated a significant correlation between lumbar extensor muscle strength, muscle fibre angle, age and gender. In the step wise regression analysis, both gender and age were identified as the most robust determinant for lumbar extensor muscle strength in older adults. However, gender was the only determinant of muscle strength in the young.
CONCLUSION: These results suggest that the decline in the lumbar extensor muscle strength in older adults was more dependent on age when compared to younger adults.