Biomedical subjects

S M Saw

Publications and source records attributed to S M Saw.

At least 37 records · Page 2Linked to original sources

PubMed2001

Academic achievement, close up work parameters, and myopia in Singapore military conscripts.

AIM: To determine the relation of refractive error to environmental factors, including close up work, in Singapore military conscripts. METHODS: A cross sectional study was conducted on 429 Singapore military conscripts. Non-cycloplegic refraction and A-scan biometry were performed in both eyes. A detailed questionnaire was administered by in-person interview to obtain information about current and past near work activity, extra tuition lessons, educational experiences, and family demographics. RESULTS: Myopia associated with the conscript having been educated in the (gifted, special, or express) educational streams (adjusted odds ratio (OR) = 3.8, 95% confidence interval CI 2.0-7.3), and having completed pre-university education (OR=4.1, 95% CI 1.9-8.8). The reported close up work activity at age 7 years did correlate with age of onset of myopia (p<0.001). In parallel, supplemental tuition lessons in primary school has (OR=2.6, 95% CI 1.4-4.9) associated with conscript myopia. Parental myopia was positively associated with myopia (p<0.001), but this relation disappeared when adjusted for environmental factors. Current (p=0.83) and past close up work activity at age 7 years (p=0.13) did not correlate with myopia. CONCLUSION: Educational level and educational stream positively related to myopia. A relation was observed with reported close up work activity in early childhood and with tuition classes during elementary school, but not with current close up work activity. These results underscore the strong influence of environment in myopia pathogenesis but a role for close up work activity remains indeterminate.

Adult↗

PubMed2001

Risk factors for hip fracture in Asian men and women: the Asian osteoporosis study.

The objectives of the Asian Osteoporosis Study (AOS) were to determine risk factors for hip fracture in men and women in four Asian countries, that is, Singapore, Malaysia, Thailand, and the Philippines. A total of 451 men and 725 women (aged 50 years and over) with hip fractures were compared with an equal number of community controls. A standardized questionnaire was administered by interview. The following relative risks (RRs) were found in women and men by multiple logistic regression: dietary calcium intake < 498 mg/day, 2.0 for women (95% CI, 1.5-2.8) and 1.5 for men (95% CI, 1.0-2.2); no load bearing activity in the immediate past, 2.0 for women (95% CI, 1.4-2.7) and 3.4 for men (95% CI, 2.3-5.1); no vigorous sport activities in young adulthood, 7.2 for women (95% CI, 4.0-13.0) and 2.4 for men (95% CI, 1.6-3.6); cigarette smoking, 1.5 for men (95% CI, 1.0-2.1); alcohol consumption 7 days a week, 2.9 for women (95% CI, 1.0-8.6) and 1.9 for men (95% CI, 1.1-3.2); fell twice or more in the last 12 months, 3.0 for women (95% CI, 1.8-4.8) and 3.4 for men (95% CI, 1.8-6.6); a history of fractures after 50 years of age, 1.8 for women (95% CI, 1.1-2.9) and 3.0 for men (95% CI, 1.6-5.6); a history of stroke, 3.8 for women (95% CI, 2.0-7.1) and 3.6 for men (95% CI, 1.8-7.1); use of sedatives, 2.5 for women (95% CI, 1.0-6.3) and 3.0 for men (95% CI, 1.0-9.7); and use of thyroid drugs, 7.1 for women (95% CI, 2.0-25.9) and 11.8 for men (95% CI, 1.3-106.0). Women who were 1.56 m or taller had an RR of 2.0 (95% CI, 1.3-3.0) for hip fracture and men who were 1.69 m or taller had an RR of 1.9 (95% CI, 1.2-3.1) for hip fracture. Based on these findings, primary preventive programs for hip fracture could be planned in Asia.

Aged↗

PubMed2001

Myopia in Singapore kindergarten children.

PURPOSE: The purpose of this study was to examine whether close-up work was related to myopia in Singapore kindergarten children. METHODS: One hundred twenty-eight children, ages 3 to 7 years, from a kindergarten in Singapore were examined by cycloplegic autorefraction. The parents also completed a questionnaire on the different types of close-up work activities each child was engaged in, socioeconomic status, and parental history of myopia. RESULTS: Myopic children spent 3.0 hours per day (median) on close-up work activity, while nonmyopic children spent 2.0 hours per day (median) on close-up work activity. The prevalence of myopia in the sample was 8.6%. CONCLUSION: Close-up work activity was not related to myopia in pre-school children.

Child↗

PubMed2001

The design and assessment of questionnaires in clinical research.

Questionnaires are one of the most commonly used tools for data collection in clinical research. Despite its simplicity and convenience of use, the design of questionnaire instruments that accurately measure health status and their determinants is nevertheless a difficult and challenging task.We review the two most important issues which are reliability and validity. Reliability can be defined as the degree to which a measure gives 'consistent' or 'reproducible' values when applied in different situations. Validity refers to the extent in which the true value of a variable is correctly measured by the instrument. For different types of questionnaire measurement instruments, specific issues of content, construct and criterion validity should be appropriately addressed. Accuracy in questionnaire-based measurement in clinical studies is achieved by paying attention to the relevant specific issues of reliability and validity during development and testing of such questionnaires.

Reproducibility of Results↗

PubMed2000

Risk factors for the development of pterygium in Singapore: a hospital-based case-control study.

PURPOSE: A hospital-based case-control study, designed to evaluate the risk factors for the development of pterygium in Singapore. METHODS: Sixty-one cases and 125 controls were interviewed at the Singapore National Eye Centre. Information on present and past (5 and 10 years ago) exposure to sunlight on weekdays and weekends, sociodemographic data, behavior lifestyle and family history of eye disease was collected. RESULTS: Patients with pterygia were mostly males, smoked and drank alcohol more often, had lower combined family incomes and were more likely to have a family history of eye disease. The adjusted odds ratios for the development of pterygia were 1.27 (95 percent confidence interval 1.06 to 1.54) and 1.31 (95 percent confidence interval 1.09 to 1.57) for participants who had spent more time in the sun five and ten years ago respectively. CONCLUSIONS: Pterygium is an important public health problem in Singapore and its development is related to the amount of sunlight exposure.

Adult↗

PubMed2000

Ophthalmic involvement in cranio-facial trauma.

OBJECTIVES: This is a retrospective descriptive case study which will look into the spectrum of ophthalmic involvement in cases with orbital and eye injuries after cranio-facial trauma and to analyse the visual and motility outcome. MATERIAL: One hundred and four cases with ophthalmic involvement after cranio-facial trauma that were referred to and seen in the eye department of a tertiary teaching hospital in Singapore between 1991-97 were included in the study. METHODS: The case records of 104 such patients were traced. The demographic data, the mode of injury, the type of fracture sustained and presence of serious eye injury were noted. The details about visual acuity, significant diplopia and enophthalmos at the first and last visits were charted. Presence of traumatic optic neuropathy including the type of treatment given was recorded. RESULTS: There was a male preponderance (82%). The industrial accidents were 21%, only next to road traffic accidents, which constituted approximately 36.5%. The predominant types of fractures seen were blow-out orbital fractures, complex fractures comprising of Le-Fort II, III, panfacial and fronto-basilar skull fractures. Diplopia was the most common presenting feature (40%) with visual acuity disturbance (23% having <6/60) as the next most common finding. Traumatic optic neuropathy was seen in 20% of patients and serious eye injury was present in 9% of patients. The incidence of traumatic optic neuropathy was significantly higher (p<0.001) in patients with complex fractures and fronto-basilar fractures, as compared to the blow-out and zygomatico-maxillary fractures. Analysis of final results indicated 15% as having significant diplopia in one or more gazes and 12.5% as having a vision of <6/60. CONCLUSION: Diplopia and visual acuity disturbances seem to be the most common ophthalmic presentations in cranio-facial trauma. A significant number of patients suffer from poor vision and significant diplopia despite treatment.

Accidents, Occupational↗

PubMed2000

Refractive errors in Singapore and Xiamen, China--a comparative study in school children aged 6 to 7 years.

PURPOSE: To compare and contrast the prevalence of myopia and other refractive errors in Xiamen city, Xiamen countryside (Southern China), and Singapore. METHODS: One hundred thirty-two schoolchildren aged 6 to 7 years from Xiamen city, 104 from Xiamen countryside, and 146 from Singapore city were recruited to join the study. Cycloplegic autorefraction, keratometry, and biometry measurements were performed on all children. RESULTS: The prevalence of myopia was 12.3% in Singapore city, 9.1% in Xiamen city, and 3.9% in Xiamen countryside. The prevalence of astigmatism was higher in Singapore compared with Xiamen. The rates of hyperopia and anisometropia were similar in all three locations. CONCLUSIONS: The myopia rate in Singapore city was higher than in Xiamen city; the lowest rates were found in Xiamen countryside. As the Chinese population from all three sites is of similar genetic stock (predominantly from Southern China), it is postulated that the differences in myopia rates in these three localities may be related to environmental factors.

Anisometropia↗

PubMed2000

Temporal variations in myopia progression in Singaporean children within an academic year.

PURPOSE: Excessive nearwork is believed to be associated with myopia development and progression. To investigate this further, we studied refractive error changes and their correlation with nearwork in a cohort of grade school children in Singapore. METHODS: Cycloplegic autorefraction was performed 5 times over 10 months on 168 children aged 7, 9, and 12 years who were further divided into myopic and nonmyopic subgroups based in their initial refractive errors. Information about nearwork was obtained through diaries filled out over 24 h at the commencement of the study. RESULTS: Myopia progression was high (overall mean: -0.87 D per year) and largely linear throughout the year, but significantly higher rates were seen after the final school examinations in 7-year-old myopes and nonmyopes. Overall, myopic groups exhibited higher progression rates than nonmyopic groups, although 33.6% of subjects from the latter groups had become myopic by the end of the study. Nearwork scores derived from the diaries were generally not well correlated with overall myopia progression. CONCLUSIONS: The tendency for myopia progression rates to increase after the final school examinations in 7-year-olds is interpreted as a delayed effect of the intense nearwork associated with preparing for them. The timing of nearwork-diary data collection at the beginning of the study could be responsible for the poor correlation between these data and overall myopia progression rates.

Child↗

PubMed2000

Factors related to the progression of myopia in Singaporean children.

PURPOSE: To examine the possible factors related to the progression of myopia in Singapore children. METHODS: One hundred fifty-three Singapore children aged 6 to 12 years were recruited to participate in a concurrent cohort study of the risk factors for the progression of myopia. Socioeconomic status, outdoor activity, and near-work activity were documented in a face-to-face clinic interview. The changes in cycloplegic subjective refraction and autorefraction were ascertained with the use of a Nidek ARK 900 over a 2-year period. RESULTS: The average rate of progression of myopia as measured by subjective refraction was -0.59 D per year (95% confidence interval -0.52, -0.66). Younger children and children who were more myopic at the beginning (refractive error worse than -2.0 D) of the study had higher myopia progression rates. CONCLUSIONS: Myopia progression was faster for younger children and for children who had more severe myopia at baseline. Socioeconomic status and near-work activity were not related to myopia progression.

Child↗

PubMed2000

Eye cancer incidence in Singapore.

AIM: To describe the epidemiological characteristics of patients with primary intraocular, conjunctival, and orbital cancers seen in Singapore from 1968 to 1995. METHODS: Epidemiological data of all cancers diagnosed in Singapore are collected by the Singapore Cancer Registry. The data of all cases of Singapore residents with eye cancers (ICD-9, site 190) were retrieved for analysis. This includes intraocular, conjunctival, and orbital cancers but excludes cancer of the eyelids. RESULTS: There were 125 patients of which 67 (53.6%) were male and 58 (46.4%) were female. The average annual age standardised incidences for male and female Singapore residents were 1.89 and 1.81 per million respectively. The most common cancer was retinoblastoma (53.6%), followed by malignant melanoma (19.2%) and squamous cell carcinoma (11.2%). The most common cancer among patients younger than 15 years was retinoblastoma (95.7%) and that for those 15 years and older was malignant melanoma (42.6%). The most common subsite was the retina (53.6%), followed by conjunctiva (12.8%), orbit (8.8%), and lacrimal gland (6.4%). CONCLUSION: The annual age standardised incidence have been stable for the 28 years studied. Retinoblastoma is much more common than melanoma in Singapore. These expanded epidemiological characteristics serve to provide ophthalmologists and epidemiologists with a foundation to monitor future disease patterns in Singapore and provide a basis for comparison with other selected populations elsewhere.

Adolescent↗

PubMed2000

The prevalence and pattern of contact lens use in a Singapore community.

PURPOSE: We conducted a cross-sectional survey to determine the prevalence, socio-demographic patterns, and characteristics of contact lens use in an electoral community in Singapore. METHODS: One thousand eight hundred fifteen persons aged between 12-55 years from 768 households were surveyed using a standardized pre-tested questionnaire. RESULTS: The percentage of contact lens wearers in the survey populations was 9.0%. Forty-two percent of surveyed individuals were myopes, 21.8% of whom wore contact lenses. Contact lens wearers tended to be young Chinese females with higher level education and incomes. Most wore monthly disposable or daily wear soft contact lenses. Convenience and cosmesis were the main reasons cited for contact lens wear. Optometrists, who prescribed the bulk of contact lenses, were also the most influential in determining consumers' choice of lenses. CONCLUSION: Information gathered in this population-based survey may be used to facilitate national eye-care planning and provide a baseline for comparison with rates of lens wear found in other countries and in future surveys.

Adolescent↗

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↗

PubMed2000

Clinical drug trials: practical problems of phase III.

INTRODUCTION: Phase III randomised clinical trials provide the highest level of evidence to support the superior effectiveness of a new drug or therapy. The main practical problems encountered in the initiation, design, conduct and completion of both investigator-initiated and sponsor-initiated phase III clinical drug trials will be reviewed. METHODS: A Medline search of clinical drug trials conducted in Singapore as well as journal articles highlighting important methodological considerations and practical problems encountered in phase III clinical trials was performed. RESULTS: Several phase III randomised clinical trials have been conducted in Singapore which include the investigation of interventions that include tramadol, estradiol patch and colloidal bismuth subcitrate. The main problems encountered in phase III clinical drug trials include difficulties with recruitment of subjects for the study, proper filing of case report forms, special problems in children and the elderly, adequate compensation for adverse events and the adequate archival of documents of the completion of trials. In investigator-initiated trials, careful attention should be given to identifying a suitable study question, choice of study design, sample size calculations and data analysis. In sponsor-initiated trials, a good working relationship with the sponsor is essential and publication terms should be spelt from the onset of the trial. CONCLUSIONS: Well-planned clinical trials led by a team of competent investigators are essential for the conduct of rigorous sponsor-initiated and investigator-initiated clinical trials.

Clinical Trials, Phase III as Topic↗

PubMed2000

Cross-sectional study of near-work and myopia in kindergarten children in Singapore.

INTRODUCTION: In view of the high and increasing myopia rates amongst young Singaporean children, we aimed to assess the relationship between near-work and myopia in 414 pre-school children aged 4 to 6 years. MATERIALS AND METHODS: We measured near-work indices such as tuition classes outside school and other possible risk factors via a questionnaire. We then measured myopia with a hand-held autorefractor. RESULTS: Children who had 3 or more hours per week of near-work classes outside school had a higher rate [odds ratio 1.39 (95% confidence interval 1.02, 2.53)] of myopia. CONCLUSIONS: This suggests that there may be an association between near-work and myopia, even at such a young age. Given the increasing emphasis on near-work in Singapore, it may be important to call for increased visual health awareness, although further studies will be needed to establish if near-work causes myopia.

Age Distribution↗

PubMed1999

Pterygium: prevalence, demography and risk factors.

Pterygium is not just a degenerative disease, but may be a proliferative disorder of the ocular surface. The etiology of pterygia has intrigued researchers for centuries. Several surveys have consistently shown that countries nearer the equator have higher rates of pterygia. A possible reason for this geographic variation is that (ultraviolet) UV B light may be a risk factor for the development of pterygia. UV B radiation may induce cellular changes in the medial limbus of the cornea. Several case-control and cross-sectional studies have attempted to accurately quantify UV light exposure and document its relationship with pterygia. Genetic attributes and other lifestyle behaviors may also contribute to the development of pterygia. However, further research efforts are needed to enable us to better understand the relative contribution of the different risk factors and how each risk factor may be linked to pterygium formation. In addition, the underlying mechanism of the effects of UV radiation needs to be further evaluated. By readdressing these unresolved issues in a newly proposed epidemiological study, new measures might be taken to reduce incidences and improve clinical managements of diseases, in addition to preventing UV exposure by eliminating other contributory factors. Meanwhile, preventive measures such as protection of the eyes by the wearing of sunglasses with UV B protective lenses and brimmed hats outdoors are recommended.

Demography↗

PubMed1999

Estimating the magnitude of close-up work in school-age children: a comparison of questionnaire and diary instruments.

BACKGROUND: Numerous scientists have noted a relationship between close-up work and myopia. METHODS: A questionnaire and four 24-hour diaries were developed to estimate close-up work activity in a cohort study of close-up work and myopia progression in Singapore children. The number of hours per day that children engaged in each type of close-up work activity over a weekday and weekend during the school term, during the examination period, and in the vacation were estimated. RESULTS: The children spent an average of 6.6 hours per day on total weighted average close-up work, of which 4.3 hours were spent on reading and writing. The intra-class correlation coefficient for the reproducibility of the questionnaire was 0.87 (95% CI 0.85-0.91). The intra-class correlation coefficient for total weighted close-up work was 0.50 (95% CI 0.34-0.66) when the questionnaire was compared with the four 24-hour diaries. The amount of close-up work activity increased with age. CONCLUSIONS: A questionnaire for close-up work was developed and proven to be reproducible and comparable to four 24-hour diaries.

Activities of Daily Living↗

PubMed1999

Distance, lighting, and parental beliefs: understanding near work in epidemiologic studies of myopia.

PURPOSE: To develop measures and indices of factors (distance of eye from object, posture, and lighting) that may modify a possible effect of near work activity on myopia. METHODS: The duration of near work, the distance of an object from eye, lighting conditions, and other sociodemographic characteristics were asked in an interview. Both distance and lighting information from the questionnaire were compared with more precise measurements. RESULTS: Diopter hours were quantified as the duration of near work multiplied by the reciprocal of the distance which the activity was performed. The intraclass correlation coefficient of the reliability of distance information for each type of near work activity ranged from 0.43 to 0.91. Home light meter readings were significantly higher for children who were reading under both room and reading light, and the distances from the questionnaire were comparable to the measured distances. CONCLUSIONS: Measures of posture, distance, and lighting factors have been developed to study the possible effect modifiers of the effects of near work on myopia.

Accommodation, Ocular↗

PubMed1999

Relation between work and myopia in Singapore women.

BACKGROUND: Work and related activities may be connected to myopia development and progression. We investigated the relationship between working activities and the onset as well as worsening of myopia. METHODS: Information on the working status of the mothers of 374 children, the number of hours of close-up work activity, and whether the mother was short-sighted, was obtained by a face-to-face interview. In addition, a subsample of 84 mothers was interviewed over the telephone and asked whether the myopia occurred in adulthood and, if so, the age of cessation of myopia. RESULTS: The adjusted odds ratio for myopia in working women was 1.9 [95% confidence interval (CI) 1.2 to 3.2] and the adjusted odds ratio for high myopia (> -6.0 D) was 1.6 (95% CI 0.8 to 3.0). Women who were working also had higher rates of adult-onset myopia, odds ratio 4.4 (95% CI 0.9 to 21.2), and a later age of cessation of myopia than nonworking women. CONCLUSIONS: In our study, work was related to myopia in Singapore women. Work may be a surrogate for another risk factor, close-up work activities such as reading, writing, and computer use.

Adolescent↗