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Objective Prior studies have reported that blood pressure (BP) has a significant influence on retinal vascular caliber both in adults and children aged 6 years and older. This study aimed to examine the association between BP and retinal vascular caliber in Singapore Chinese preschoolers 4 to 5 years of age. Design Population-based, cross-sectional study. Participants A total of 385 eligible and healthy Singapore Chinese children 4 to 5 years of age who were recruited in The Strabismus, Amblyopia and Refractive Error Study in Singaporean Chinese Preschoolers from May 2006 through October 2008 underwent BP measurements and retinal photography. Methods According to standard protocols, BP was measured with an automatic Omron sphygmomanometer (Omron HEM 705 LP, Omron Healthcare, Inc., Bannockburn, IL) and a retinal photograph was obtained with a Canon 45° digital retinal camera (Model CR6-NM45, Canon, Inc., Tokyo, Japan) after pupil dilation. Anthropometric and optical biometric measurements such as height, weight, and axial length were obtained also. Information regarding sociodemographic status and child birth information was supplied by parents in either English or Chinese questionnaires. Main Outcome Measures The computer imaging program was used to measure the caliber of all retinal arterioles and venules located in zone B. The central retinal arteriolar equivalent and central retinal venular equivalent were estimated by using a revised Knudtson-Parr-Hubbard formula. Results The mean retinal arteriolar and venular calibers were 156.19 μm and 220.01 μm in boys and 161.97 μm and 224.22 μm in girls. Higher systolic BP was associated with narrower retinal arterioles. After adjusting for age, gender, father's education, body mass index, birth weight, axial length, and caliber of the fellow retinal vessel, each 10-mmHg increase in systolic BP was associated with 2.00 μm (95% confidence interval, 0.39–3.61; P = 0.02) of retinal arteriolar narrowing and 2.51 μm (95% confidence interval, 0.35–4.68; P = 0.02) of retinal venular widening. However, neither diastolic BP nor mean arterial BP was associated with retinal arteriolar or venular caliber. Conclusions In very young children 4 to 5 years of age, higher systolic BP was associated with narrower retinal arterioles and wider retinal venules. This suggests that elevated BP may affect the retinal microvasculature from early childhood. Financial Disclosure(s) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Purpose: An association between birth order and reduced unaided vision (a surrogate for myopia) has been observed previously. We examined the association between birth order and myopia directly in four subject groups. Methods: Subject groups were participants in (1) the Avon Longitudinal Study of Parents and Children (ALSPAC; UK; age 15 years; N = 4401), (2) the Singapore Cohort Study of Risk Factors for Myopia (SCORM; Singapore; age 13 years; N = 1959), (3) the Raine Eye Health Study (REHS; Australia; age 20 years; N = 1344), and (4) Israeli Defense Force Pre-recruitment Candidates (IDFC; Israel; age 16–22 years; N = 888,277). The main outcome was odds ratios (OR) for myopia in first-born versus non-first-born individuals after adjusting for potential risk factors. Results: The prevalence of myopia was numerically higher in first-born versus non-first-born individuals in all study groups, but the strength of evidence varied widely. Adjusted ORs (95% confidence intervals, CIs) were: ALSPAC, 1.31 (1.05–1.64); SCORM, 1.25 (0.89–1.77); REHS, 1.18 (0.90–1.55); and IDFC, 1.04 (1.03–1.06). In the large IDFC sample, the effect size was greater (a) for the first-born versus fourth- or higher-born comparison than for the first-born versus second/third-born comparison (p

To determine the risk factors for strabismus and amblyopia in young Singapore Chinese children.A total of 3009 children were recruited for the population-based cross-sectional Strabismus, Amblyopia and Refractive Error in Singaporean Preschoolers Study (STARS). Strabismus was defined as any tropia identified on cover test. Visual acuity was measured in children aged 30-72 months with a logMAR chart where possible and the Sheridan-Gardiner test if not. Amblyopia was defined based on visual acuity and refractive error or presence of strabismus or past/present visual axis obstruction. Parents completed questionnaires on family, prenatal and birth histories.Our study showed that 24 children aged 6-72 months (1.2%) had strabismus (20 with exotropia), and 20 children aged 30-72 months (0.8%) were amblyopic. After multivariate analysis, strabismus was associated with astigmatism ≥1.00 diopter (D; p = 0.03), amblyopia (p = 0.003), a sibling with strabismus (p 0.001), and families with lower parental education (p = 0.04). In addition to strabismus, amblyopia was associated with anisometropia ≥1.00 D (p 0.001) and astigmatism ≥1.00 D (p 0.001). No association was noted between either strabismus or amblyopia and prematurity, maternal age or smoking.This study highlights the importance of family history in strabismus, and the close associations between refractive error and strabismus with amblyopia. These factors play a more important role in young Singapore Chinese children.

To examine the pattern of myopia-related macular and optic disc changes in Singapore adults with high myopia (spherical equivalent ≤-6.00 diopters).Asian adults with high myopia from 3 population-based surveys.Adults 40 years and older (n = 359) with high myopia were pooled from 3 population-based surveys in Singapore Asians: (1) the Singapore Prospective Study Program (SP2, n = 184); (2) the Singapore Malay Eye Study (SiMES, n = 98); and (3) the Singapore Indian Eye Study (SINDI, n = 77). All study participants underwent standardized refraction and fundus photography, and SiMES and SINDI subjects also completed ocular biometry measurements. Myopia-related macular (posterior staphyloma, lacquer cracks, Fuchs spot, myopic chorioretinal atrophy, and myopic choroidal neovascularization) and optic disc (optic nerve head tilt, optic disc dimensions, and peripapillary atrophy) changes were evaluated.The most common myopia-related macular finding in adults with high myopia was staphyloma (23%), followed by chorioretinal atrophy (19.3%). There were few cases of lacquer crack (n = 6, 1.8%), T-sign (n = 6, 1.8%), retinal hemorrhage (n = 3, 0.9%), active myopic choroidal neovascularization (n = 3, 0.9%), and no case of Fuchs spot. The most common disc finding associated with high myopia was peripapillary atrophy (81.2%), followed by disc tilt (57.4%). Staphyloma and chorioretinal atrophy increased in prevalence with increasing age, increasing myopic refractive error, and increasing axial length (all P.001). Ethnicity comparisons demonstrated the highest proportion of staphyloma (P = .04) among Malays, the highest proportion of peripapillary atrophy (P = .01) and disc tilt (P.001) among Chinese, and the largest cup-to-disc ratio (P .001) among Indians.Staphyloma and chorioretinal atrophy lesions were the most common fundus findings among Asian adults with high myopia. In this population, tilted discs and peripapillary atrophy were also common, while choroidal neovascularization and Fuchs spot were rare. In contrast with Singapore teenagers, in whom tilted disc and peripapillary atrophy were common while staphyloma and chorioretinal atrophy were rare, pathologic myopia appears to be dependent on the duration of disease and, thus, age of the individual.

To examine the association between body fatness indices and retinal vascular calibre in Singapore Chinese children.We recruited 136 Singapore Chinese children aged 6-16 years from the STARS (The Strabismus, Amblyopia and Refractive Error Study in Singaporean Chinese Preschoolers) Family study in 2008-2010. Anthropometric measurements including weight, height and triceps skinfold (TSF) and right eye retinal photographs were performed. TSF was measured with Holtain-Tanner calliper on the back of the arm and midway between the point of the acromoion and olecranon process while the arm was hanging relaxed. TSF and BMI threshold (cut-off points for overweight and obesity) were defined as 85th and above of age- and gender-specific TSF and BMI standard charts which were based on American representative survey data.The mean retinal arteriolar and venular calibres were 155.78 ? 15.02 ?m and 219.66 ? 21.88 ?m, respectively in the STARS Family study. Each standard deviation (SD) increase in TSF (4.49 mm) and BMI (3.52 kg/m(2)) was associated with a 2.94 ?m (p = 0.012) and a 3.40 ?m (p = 0.005) widening in retinal venular calibre, respectively. Compared with children with TSF and BMI below threshold, children with TSF and BMI above threshold had a 10.21 ?m (p = 0.001) and a 9.33 ?m (p = 0.021) increase in retinal venular calibre, respectively.Greater TSF and BMI are associated with wider retinal venular calibre in healthy children aged 6 years and above. These findings suggest a possible effect of abnormal body fatness indices on early retinal vascular changes that reflect microvasculature in children.

PURPOSE. Peripheral hyperopia was hypothesized to stimulate axial elongation. This study describes peripheral refraction and its associations with central refractive error in young Singapore Chinese children.METHODS. Two hundred fifty children aged 40 months or older recruited from the Strabismus, Amblyopia, and Refractive Error in Young Singapore Children study were included in this analysis. Peripheral refraction was measured after pupil dilation using an infrared autorefractor. A total of five measurements were captured: central visual axis and 15 and 30 eccentricities in the nasal and temporal visual fields.RESULTS. The mean age of the participants recruited was 83 +/- 36 months. There were 37 children with high and moderate myopia ( 1.0 D; 18.8%). Compared with the central axis, children with high and moderate myopia had relative hyperopia at all peripheral eccentricities (P < 0.001), whereas children with low myopia had relative hyperopia only at the temporal and nasal 30 degrees (P < 0.001), but not at the nasal and temporal 15 degrees. Children with emmetropia and hyperopia had peripheral relative myopia at all eccentricities (P < 0.001). A significant correlation between the nasal and temporal refractive error at 30 degrees was noted (Spearson's correlation coefficient = 0.85, P < 0.001).CONCLUSIONS. Young myopic Singapore Chinese children had relative hyperopia in the periphery. This study substantiates previous studies in older children and in Caucasian subjects. (Invest Ophthalmol Vis Sci. 2011; 52:1181-1190) DOI:10.1167/iovs.10-5601

PURPOSE To evaluate the influence of refractive error and axial length (AL) on retinal vascular network geometry measurements in an adult Asian population. METHODS This was a population-based, cross-sectional study on 2882 persons with diabetes in the Singapore Malay Eye Study. Spherical equivalent refraction was assessed using an autokeratorefractometer and subjective refraction. AL retinal vascular caliber, tortuosity, and branching characteristics were quantified from retinal fundus photographs using a semiautomated computer-assisted program according to a standardized protocol. RESULTS In multivariate analyses adjusting for age, sex, education, smoking, blood pressure, diabetes status, and antihypertensive medication use, longer AL and more myopic refraction were associated with narrower retinal arterioles and venules (P ≤ 0.001 for all) and less tortuous (straighter) arterioles (P < 0.001 for both). Longer AL and more myopic refraction were also associated with increased branching coefficients in both arterioles (P < 0.001 for both) and venules (P = 0.02 and P < 0.001, respectively). Longer AL and more myopic refraction were associated with more acute branching angles in arterioles (P < 0.001 for both) but not venules. CONCLUSIONS Myopic refractive errors and longer AL are associated with narrower retinal arterioles and venules, less tortuous arterioles, and increased branching coefficients in both arterioles and venules. These findings provide insights into ocular blood flow in myopia and also suggest that future studies evaluating these retinal parameters should account for the influence of AL and refractive error.

PURPOSE To examine changes in lens power during refractive development in Singapore Chinese children. METHODS Children aged six to nine years from three Singapore schools were invited to participate in the Singapore Cohort study Of the Risk factors for Myopia (SCORM) study. Cycloplegic refractions and biometry were measured annually in the schools over a five year period from 1999. Children were classified into five refractive error groups: persistent hyperopia, emmetropizing hyperopia, persistent emmetropia, newly developed myopia, or persistent myopia. Crystalline lens power was calculated using Bennett's formula. The rate of change per year across the refractive groups was adjusted for age and sex using General Linear Models. RESULTS There were 1747 children with at least three sets of measurements for lens power calculations. The mean age at baseline was 7.94 ± 0.84 years and the mean spherical equivalent refraction was -0.41 ± 1.71 diopters (D). Lower lens power and lower lens thickness were associated with persistent myopia. As expected, the newly developed myopes and the persistent myopes showed the largest changes in axial length (AL). Changes in lens power and thickness at follow-up were similar in all refractive groups, except for the newly developed myopes, who showed significantly greater decreases in lens power (0.36 vs. 0.29 D/year; P < 0.001) and lens thickness (0.015 vs. 0.0003 mm/year; P < 0.001) than the persistently emmetropic group. CONCLUSIONS Newly developed myopes showed a significantly greater decrease in lens power than other refractive groups, which may be linked to rapid changes in AL and refraction that occur around the onset of myopia.

Purpose. To determine variations in eye volume, surface area, and shape with refractive error in young children using a three-dimensional magnetic resonance imaging (MRI) model. Methods. A subset of Singaporean Chinese boys enrolled in the population-based Strabismus, Amblyopia, and Refractive Error in Singapore (STARS) study underwent MRI using a 3-Tesla whole body scanner with a 32-channel head coil. Eye volume and surface area were measured. Eye shape was assessed qualitatively from the three-dimensional models and quantitatively by measurement of the longitudinal axial length (LAL), horizontal width, and vertical height along the cardinal axes. Results. One hundred thirty-four eyes of 67 subjects (mean age, 77.9 ± 3.9 months) were analyzed. The mean spherical equivalent (SE) refraction was 0.65 ± 0.92 D (range, -2.31 to 4.13 D). More myopic SE was associated with larger surface area (-20.59 [-37.09 to -4.10] mm 2 /D; P = 0.01) but not volume. In age-height adjusted models, more myopic SE was associated with longer LAL (-1.94 [-2.47 to -1.41] mm/D; P < 0.001) and greater width (-1.12 [-1.26 to -0.99] mm/D; P < 0.001) but not height (0.64 [-2.55 to 3.82] mm/D; P = 0.70). In nonmyopic subjects, less hyperopic SE was associated with longer AL (-0.40 [-0.71 to -0.10] mm/D; P = 0.01), width (-0.59 [-0.84 to -0.34] mm/D; P < 0.001), and height (-0.40 [-0.64 to -0.17] mm/D; P = 0.001). In three-dimensional models, myopic eyes conformed to an axial elongation model with a prolate profile in the axial plane, whereas nonmyopic eyes showed global expansion. Conclusions. Eye surface area increases with myopia in young children. Eye shape is different in myopia, even in its early stages. Axial globe enlargement occurs in myopic eyes leading to a prolate shape, whereas nonmyopic eyes enlarge globally in length, width, and height. © 2011 The Association for Research in Vision and Ophthalmology, Inc.

PURPOSE. Relative peripheral hyperopia has been associated with central myopia. This study was conducted to determine whether baseline relative peripheral hyperopia is associated with an increased risk of developing myopia or myopia progression in young Singapore Chinese children. METHODS. One hundred eighty-seven children who participated in the Peripheral Refraction in Preschool Children (PREP) Study at baseline underwent a follow-up examination. Autorefraction was performed at five eccentricities with an infrared autorefractor after cycloplegia: central axis and 15° and 30° eccentricities in the nasal and temporal visual fields. The primary outcomes were development of myopia among children who were nonmyopic at baseline, and myopia progression in those who were myopic at baseline. RESULTS. The mean age of the children at baseline was 7.2 ± 3.0 years, and the mean duration of follow-up was 1.26 years. At baseline, 96 children were myopic (mean central spherical equivalent [SE] -2.75 ± 1.72 D) and 91 were nonmyopic (mean central SE 0.76 ± 0.81 D). Baseline relative peripheral hyperopia was not associated with a greater likelihood of becoming myopic or myopia progression. At follow-up, children who remained nonmyopic (n = 24) retained relative peripheral myopia at all eccentricities, whereas those who became myopic (n = 67) developed relative peripheral hyperopia at the nasal (+0.44 ± 0.72 D) and temporal 30° (+0.13 ± 0.74 D). The mean change in central SE was -1.51 ± 0.63 D/y for children who developed myopia, -0.82 ± 0.76 D/y for children who were myopic at baseline, and -1.05 ± 0.80 D/y for all children. CONCLUSIONS. Baseline peripheral refraction did not predict the subsequent onset of myopia or influence the progression of myopia.

To determine the prevalence and risk factors for refractive errors in middle-aged to elderly Singaporeans of Indian ethnicity.A population-based, cross-sectional study of Indians aged over 40 years of age residing in Southwestern Singapore was conducted. An age-stratified (10-year age group) random sampling procedure was performed to select participants. Refraction was determined by autorefraction followed by subjective refraction. Myopia was defined as spherical equivalent (SE)-0.50 diopters (D), high myopia as SE-5.00 D, astigmatism as cylinder-0.50 D, hyperopia as SE0.50 D, and anisometropia as SE difference1.00 D. Prevalence was adjusted to the 2000 Singapore census.Of the 4497 persons eligible to participate, 3400 (75.6%) were examined. Complete data were available for 2805 adults with right eye refractive error and no prior cataract surgery. The age-adjusted prevalence was 28.0% (95% confidence interval [CI], 25.8-30.2) for myopia and 4.1% (95% CI, 3.3-5.0) for high myopia. There was a U-shaped relationship between myopia and increasing age. The age-adjusted prevalence was 54.9% (95% CI, 52.0-57.9) for astigmatism, 35.9% (95% CI, 33.7-38.3) for hyperopia, and 9.8% (95% CI, 8.6-11.1) for anisometropia. In a multiple logistic regression model, adults who were female, younger, taller, spent more time reading and writing per day, or had astigmatism were more likely to be myopic. Adults who were older or had myopia or diabetes mellitus had higher risk of astigmatism.In Singapore, the prevalence of myopia in Indian adults is similar to those in Malays, but lower than those in Chinese. Risk factors for myopia are similar across the three ethnic groups in Singapore.