S.-M. Saw

Prevalence and risk factors associated with dry eye symptoms: a population based study in Indonesia

Aim: To determine the prevalence and identify associated risk factors for dry eye syndrome in a population in Sumatra, Indonesia. Methods: A one stage cluster sampling procedure was conducted to randomly select 100 households in each of the five rural villages and one provincial town of the Riau province, Indonesia, from April to June 2001. Interviewers collected demographic, lifestyle, and medical data from 1058 participants aged 21 years or over. Symptoms of dry eye were assessed using a six item validated questionnaire. Presence of one or more of the six dry eye symptoms often or all the time was analysed. Presence of pterygium was documented. Results: Prevalence of one or more of the six dry eye symptoms often or all the time adjusted for age was 27.5% (95% confidence interval (CI) 24.8 to 30.2). After adjusting for all significant variables, independent risk factors for dry eye were pterygium (p<0.001, multivariate odds ratio (OR) 1.8; 95% CI 1.4 to 2.5) and a history of current cigarette smoking (p=0.05, multivariate OR 1.5; 95% CI 1.0 to 2.2). Conclusions: This population based study provides prevalence rates of dry eye symptoms in a tropical developing nation. From our findings, pterygium is a possible independent risk factor for dry eye symptoms.

The epidemiology of age related eye diseases in Asia

In the past decade, several large population based studies have provided new information on the prevalence of visual impairment and the major age related eye diseases in Asia. These include epidemiological studies from India, Taiwan, Mongolia, Singapore, and Japan. In particular, the epidemiology of refractive errors and glaucoma has been well characterised, providing insights not only into the public health implications of these conditions, but also into anatomical changes of the eye with ageing. In contrast, there are few well conducted population based studies on diabetic retinopathy and age related macular degeneration in Asia, two conditions that are likely to be important causes of blindness in the future.

Methodology of the Singapore Indian Chinese Cohort (SICC) eye study: Quantifying ethnic variations in the epidemiology of eye diseases in Asians

Purpose: Current knowledge of ethnic variability in the epidemiology of major eye diseases in Asia is limited. This report summarizes the rationale and study design of the Singapore Indian Chinese Cohort (SICC) Eye Study, a population-based study of ethnic South Asian (Indians) and East Asian (Chinese) older adults in Singapore. Methods: The SICC examined a population-based cross-sectional sample of 3,300 ethnic Indians and 3,300 ethnic Chinese aged 40–80+ years residing in the South-Western part of Singapore. Results: From two lists of 12,000 names of each ethnic group provided by the Ministry of Home Affairs, age-stratified random sampling was used to select 6,350 names in each group, with a target sample size of 3,300. Invitations were sent to attend a central clinic using letters, telephone calls and home visits. Examination procedures included interviews, measurement of blood pressure, anthropometry, presenting and best-corrected visual acuity, subjective refraction, ocular biometry, Goldmann applanation tonometry, slit-lamp biomicroscopy, optic disc imaging and digital photography of the lens and retina, using a standardized protocol. Selected participants underwent gonioscopic examination, visual field testing, and anterior and posterior segment optical coherence tomography. Blood, tear, and urine samples were collected for biochemical analyses, and stored for genetic and proteomic studies. Conclusions: In conjunction with the Singapore Malay Eye Study, the SICC study will permit an in-depth evaluation of the prevalence, risk factors, and impact of major eye diseases in Chinese, Indians and Malays, three distinct Asian ethnic groups, whose combined numbers represent half the world’s population.

Pterygium in Indonesia: prevalence, severity and risk factors.

Aim: To determine prevalence rates, severity, and risk factors for pterygium in adults in provincial Indonesia and to validate a clinical grading scheme in a population based setting. Methods: A population based prevalence survey of 1210 adults aged 21 years and above was conducted in five rural villages and one provincial town in Riau province, Sumatra, Indonesia, an area near to the equator. A one stage household cluster sampling procedure was employed: 100 households were randomly selected from each village or town. Pterygia were graded for severity (T1 to T3, by visibility of episcleral vessels) and the basal and apical extent measured by an ophthalmologist (GG) with a hand held slit lamp. Refraction was measured by hand held autorefractor (Retinomax). Face to face household interviews assessed outdoor activity, occupation, and smoking. The participation rate was 96.7%. Results: The mean age was 36.6 years (SD 13.1), 612 were male. The age adjusted prevalence rate of any pterygium was 10.0% (95% confidence intervals (CI) 8.2 to 11.7) and of bilateral pterygia was 4.1% (95% CI 2.9 to 5.3). There was a significant dose-response relation with age (2.9% (95% CI 0.4 to 5.8) for 21–29 years versus 17.3% (95% CI 10.4 to 24.2) 50 years and above; p for trend <0.001) and occupations with more time outdoors (p for trend = 0.02). This was true for both sexes, all grades of lesion (T1 to T3), and bilateral disease. A multivariate logistic regression model showed pterygium was independently related to increasing age and outdoor activity 10 years earlier. The mean basal diameter = 3.3 mm (SD 1.51, range 0.1–9.5) and extent from limbus = 1.4 mm (SD 1.18, range 0.1–8.0). Higher grade pterygia were larger for basal and apical extent (p for trend <0.001). The presence of pterygium was associated with astigmatism (defined as cylinder at least −0.5 dioptres (D); p <0.001). This association increased with increasing grade of lesion (p for trend <0.001). Median cylinder for those with pterygium (−0.50 D) was greater than for those without (−0.25D), (p <0.001), and increased with higher grade of lesion (p for trend <0.001). For eyes with pterygia, magnitude of astigmatism was associated with greatest extent from the limbus, (p = 0.03), but not basal width (p = 0.99). Conclusions: There is a high prevalence rate of pterygia in provincial Sumatra. The independent increase with age and past outdoor activity (a surrogate for sun exposure) is consistent with previous findings. Clinical grading of pterygium morphology by the opacity of the lesion was a useful additional marker of severity.

Myopia: attempts to arrest progression

Previous studies have evaluated the efficacy of several interventions to decrease the progression of myopia. These include devices that alter the perception of the visual environment and pharmacological treatments. There is no conclusive evidence thus far that alteration of the pattern of spectacle wear, bifocals, ocular hypotensives, or contact lenses retards the progression of myopia. Several randomised clinical trials have demonstrated that the rate of progression of myopia is lower in children given atropine eye drops than those given placebo. However, atropine is associated with short term side effects such as photophobia and possible long term adverse events including light induced retinal damage and cataract formation. Other more selective antimuscarinic agents such as pirenzipine are presently being evaluated. Further well conducted randomised clinical trials with large sample sizes and adequate follow up designed to evaluate treatments to retard the progression of myopia should be conducted, since the identification of an effective intervention may have a greater public health impact on the burden and morbidity from myopia than the few treatments currently available.

Prevalence and risk factors of retinal vein occlusion in an Asian population

Aim: To describe the prevalence and risk factors of retinal vein occlusion (RVO) in an Asian population. Methods: The Singapore Malay Eye Study is a population-based, cross-sectional study of 3280 (78.7%) Malay adults (aged 40–80 years) living in Singapore. All participants underwent retinal photography, standardised interview, clinical examinations and laboratory investigations. RVO (central or branch) was graded based on the Blue Mountains Eye Study (BMES) protocol from retinal photographs. Results: The overall prevalence of RVO was 0.7% (n = 22) (95% CI 0.4 to 1.0) (18 branch and five central RVO cases). There was no significant gender difference in RVO prevalence. RVO was associated with higher systolic blood pressure (age-adjusted odds ratio (OR) per SD increase 1.54, CI 1.02 to 2.31), ocular perfusion pressure (OR per SD increase 1.49, CI 1.03 to 2.16), a history of angina (OR 5.18, CI 1.49 to 18.0) and heart attack (OR 4.26, CI 1.47 to 12.3), and higher total cholesterol (OR per SD increase 1.55, CI 1.07 to 2.24) and LDL (OR per SD increase 1.47, CI 1.02 to 2.12) cholesterol levels. Conclusions: The prevalence of RVO in this Asian population was lower than Caucasians in the BMES, although the systemic associations of RVO were largely similar to BMES and other studies.

Intraocular pressure associations with refractive error and axial length in children

Aim: To assess whether intraocular pressure (IOP) is associated with refractive error or axial length in children. Methods: Of subjects from the Singapore Cohort Study of the Risk Factors for Myopia (SCORM), 636 Chinese children aged 9–11 years from two elementary schools underwent non-contact tonometry, cycloplegic autorefraction, and A-scan biometry during 2001. For analyses, refractive error was categorised into four groups; hypermetropia (spherical equivalent refraction (SE) ⩾+1.0D), emmetropia (−0.5D<SE<+1.0D), low myopia (−3.0D<SE⩽−0.5D) and high myopia (SE⩽−3.0D). Results: Of the 636 children examined, 50.6% were male. The mean IOP was 16.6 (SD 2.7) mm Hg. There were no significant IOP differences between low (mean IOP = 16.4 (2.8) mm Hg) or high myopes (16.7 (2.5) mm Hg) and emmetropes (16.7 (2.9) mm Hg), p = 0.57. IOP was not correlated with spherical equivalent refraction (Spearman correlation, r = 0.009) or axial length (r = 0.030). In regression analyses adjusting for diastolic blood pressure, neither spherical equivalent (regression coefficient = 0.014) nor axial length (regression coefficient = 0.027) were significantly associated with IOP. Conclusion: These findings do not support an association between IOP and refractive error or axial length in children. This questions postulated roles of IOP in the pathogenesis of myopia.

Replication of 13 obesity loci among Singaporean Chinese, Malay and Asian-Indian populations

Objective:Recent genome-wide association studies (GWAS) have identified 38 obesity-associated loci among European populations. However, their contribution to obesity in other ethnicities is largely unknown.Methods:We utilised five GWAS (N=10 482) from Chinese (three cohorts, including one with type 2 diabetes and another one of children), Malay and Indian ethnic groups from Singapore. Data sets were analysed individually and subsequently in combined meta-analysis for Z-score body-mass index (BMI) associations.Results:Variants at the FTO locus showed the strongest associations with BMI Z-score after meta-analysis (P-values 1.16 × 10−7–7.95 × 10−7). We further detected associations with nine other index obesity variants close to the MC4R, GNPDA2, TMEM18, QPCTL/GIPR, BDNF, ETV5, MAP2K5/SKOR1, SEC16B and TNKS/MSRA loci (meta-analysis P-values ranging from 3.58 × 10−4–1.44 × 10−2). Three other single-nucleotide polymorphisms (SNPs) from CADM2, PTBP2 and FAIM2 were associated with BMI (P-value ⩽0.0418) in at least one dataset. The neurotrophin/TRK pathway (P-value=0.029) was highlighted by pathway-based analysis of loci that had statistically significant associations among Singaporean populations.Conclusion:Our data confirm the role of FTO in obesity predisposition among Chinese, Malays and Indians, the three major Asian ethnic groups. We additionally detected associations for 12 obesity-associated SNPs among Singaporeans. Thus, it is likely that Europeans and Asians share some of the genetic predisposition to obesity. Furthermore, the neurotrophin/TRK signalling may have a central role for common obesity among Asians.

Impact of symptomatic dry eye on vision-related daily activities: the Singapore Malay Eye Study.

PurposeTo examine the impact of symptomatic dry eye on vision-related daily activities.MethodsA population-based survey of eye diseases was conducted on 3280 (78.7% response rate) Malay persons aged ⩾40 years, who were randomly selected from designated areas in southwestern Singapore. Participants were administered a standardized dry eye questionnaire consisting of six questions on symptoms, a questionnaire on vision-related daily activities, and underwent a comprehensive systemic and ocular examination. Symptomatic dry eye was defined as one or more self-reported symptoms that were frequently present (ranked as often or all the time). Logistic regression method was used to examine the relationship of symptomatic dry eye with difficulty in performing daily activities.ResultsIn adults without visual impairment, symptomatic dry eye after adjusting for age, gender, and presenting visual acuity was significantly associated with difficulty in vision-related activities such as navigating stairs (odds ratio (OR)=1.96, 95% confidence interval (CI): 1.28–3.00), recognizing friends (OR=1.99, 95% CI: 1.45–2.73), reading road signs (OR=1.87, 95% CI: 1.36–2.57), reading newspaper (OR=1.50, 95% CI: 1.11–2.04), watching television (OR=1.90, 95% CI: 1.26–2.87), cooking (OR=1.94, 95% CI: 1.02–3.71), and driving at night (OR=2.06, 95% CI: 1.32–3.21).ConclusionSymptomatic dry eye was associated with difficulty in performing vision-dependent tasks, independent of visual acuity and other factors. These findings have public health significance and suggest that the visual dysfunction in dry eye should be further characterized.

Prenatal maternal depression alters amygdala functional connectivity in 6-month-old infants.

Prenatal maternal depression is associated with alterations in the neonatal amygdala microstructure, shedding light on the timing for the influence of prenatal maternal depression on the brain structure of the offspring. This study aimed to examine the association between prenatal maternal depressive symptomatology and infant amygdala functional connectivity and to thus establish the neural functional basis for the transgenerational transmission of vulnerability for affective disorders during prenatal development. Twenty-four infants were included in this study with both structural magnetic resonance imaging (MRI) and resting-state functional MRI (fMRI) at 6 months of age. Maternal depression was assessed at 26 weeks of gestation and 3 months after delivery using the Edinburgh Postnatal Depression Scale. Linear regression was used to identify the amygdala functional networks and to examine the associations between prenatal maternal depressive symptoms and amygdala functional connectivity. Our results showed that at 6 months of age, the amygdala is functionally connected to widespread brain regions, forming the emotional regulation, sensory and perceptual, and emotional memory networks. After controlling for postnatal maternal depressive symptoms, infants born to mothers with higher prenatal maternal depressive symptoms showed greater functional connectivity of the amygdala with the left temporal cortex and insula, as well as the bilateral anterior cingulate, medial orbitofrontal and ventromedial prefrontal cortices, which are largely consistent with patterns of connectivity observed in adolescents and adults with major depressive disorder. Our study provides novel evidence that prenatal maternal depressive symptomatology alters the amygdalas functional connectivity in early postnatal life, which reveals that the neuroimaging correlates of the familial transmission of phenotypes associated with maternal mood are apparent in infants at 6 months of age.