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Biomedical subjects

W H Chua

Publications and source records attributed to W H Chua.

6 recordsLinked to original sources
PubMed2005

Eye growth changes in myopic children in Singapore.

AIMS: To assess the longitudinal changes in biometric parameters and associated factors in young myopic children aged 7--9 years followed prospectively in Singapore. METHODS: Children aged 7--9 years from three Singapore schools were invited to participate in the SCORM (Singapore Cohort study Of the Risk factors for Myopia) study. Yearly eye examinations involving biometry measures were performed in the schools. Only myopic children (n=543) with 3 year follow up data were included in this analysis. RESULTS: The 3 year increases in axial length, anterior chamber depth, lens thickness, vitreous chamber depth, and corneal curvature were 0.89 mm, -0.02 mm, -0.01 mm, 0.92 mm, and 0.01 mm, respectively. Children who were younger, female, and who had a parental history of myopia were more likely to have greater increases in axial length. After adjustment for school, age, sex, race, parental myopia and reading in books per week, the age (p<0.001), sex (p=0.012), and parental myopia (p=0.027) remained significantly associated with the 3 year change in axial length. Reading in books per week, however, was not associated with axial length change. Children with faster rates of progression of myopia had greater increases in axial length (Pearson correlation coefficient (r)=-0.69) and vitreous chamber depth (r=-0.83). CONCLUSIONS: The 3 year change in axial length of Singapore children aged 7--9 years at baseline was high and greater in younger children, females, and children with a parental history of myopia. Myopia progression was driven largely by vitreous chamber depth increase.

Anterior Chamber↗
PubMed2001

Myopia and night lighting in children in Singapore.

AIM: To examine the role of night time lighting and myopia in children in Singapore METHODS: A cross sectional study was conducted on 1001 children in two Singapore schools. Cycloplegic refraction and A-scan biometry measurements were made in both eyes. A detailed questionnaire was completed by the parents to obtain information on night time lighting, near work activity, educational and demographic factors. RESULTS: There was no difference in myopia prevalence rates in children exposed to night time light (33.1%) compared with children who slept in the dark (31.4%) before age 2. In addition, vitreous chamber depth was not related to night light (p = 0.58) before age 2. These results remained even after controlling for near work. CONCLUSION: Myopia is not associated with night light in Asian populations.

Anterior Chamber↗
PubMed2000

Myopia: gene-environment interaction.

INTRODUCTION: Myopia has reached epidemic proportions in Japan, Hong Kong, Taiwan and Singapore. This review summarises the evidence for environmental and genetic factors as well as gene-environment interaction for myopia for both epidemiologic studies as well as animal models. METHODS: A literature review was conducted after a Medline search on articles on the genetic or environmental aetiology of myopia in animal or epidemiologic studies. Articles on the methodology of gene-environment studies were also reviewed. All articles reviewed were articles published in peer-reviewed journals. RESULTS: Cross-sectional studies have found a positive association between myopia and near work activity such as reading and writing. Likewise, laboratory research has shown that environmental factors such as visual deprivation may lead to the development of myopia in animals. While linkage studies in humans are currently being conducted to identify possible markers for myopia in the human genome, several neurotransmitters, modulators and growth factors that influence refractive development have already been identified in animal models that may help identify candidate genes. Epidemiologic studies have also evaluated the combined effects of hereditary factors, environmental factors and gene-environment interaction on myopia development. CONCLUSIONS: Both genes and environmental factors may be related to myopia. There are no conclusive studies at present, however, that identify the nature and extent of possible gene-environment interaction. Further linkage analysis, affected sib-pair studies, and family-based association studies may better identify the nature of gene-environment interaction.

Animals↗
PubMed1995

The surgical anatomy of thoracic facet denervation.

Thoracic percutaneous facet denervation has been employed for the treatment of thoracic zygapophysial joint pain. But the surgical anatomy of this procedure has been assumed to be the same as for lumbar medial branch neurotomy. To establish the anatomical basis for thoracic medial branch neurotomy, an anatomical study was undertaken. Using an X40 dissecting microscope, a total of 84 medial branches from 7 sides of 4 embalmed human adult cadavers were studied. The medial branches of the thoracic dorsal rami were found to assume a reasonably constant course. Upon leaving the intertransverse space, they typically crossed the superolateral corners of the transverse processes and then passed medially and inferiorly across the posterior surfaces of the transverse processes before ramifying into the multifidus muscles. Exceptions to this pattern occurred at mid-thoracic levels (T5-T8). Although the curved course remained essentially the same, the inflection occurred at a point superior to the superolateral corner of the transverse process. At no time during the dissection were nerves encountered crossing the junctions between the superior articular processes and transverse processes which have been the target points advocated for thoracic facet denervation. Rather, the results of this study indicate that the superolateral corners of the transverse processes are more accurate target points.

Adult↗