Influence of blood pressure on retinal vascular caliber in young children.

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.

Heidelberg retinal tomography of optic disc and nerve fiber layer in singapore children: variations with disc tilt and refractive error.

PURPOSE: To evaluate the relationships in Singapore school children between optic nerve head parameters and retinal nerve fiber layer thickness images by using the Heidelberg Retinal Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) and determining optic disc tilt and refractive error. METHODS: This was a cross-sectional study involving 316 children 11 and 12 years of age (163 girls and 153 boys) selected randomly from one of the three schools in the Singapore Cohort study of Myopia. A total of 13 optic disc parameters were obtained from HRT images acquired before cycloplegia. Refractive errors were measured by cycloplegic autorefraction. The presence of optic disc tilt or otherwise was determined by two independent assessors using stereoscopic viewing of retinal photographs. RESULTS: Of the 316 children, 142 had tilted discs. The tilting of optic discs was associated with a smaller disc, rim or cup area measurements, cup-to-disc area ratios, cup volumes or cup depths, but with a larger measured rim volume, rim-to-disc area ratios, height variation of the contour, retinal nerve fiber layer thicknesses or volumes, and a more negative cup shape measure (all P < 0.001). Decreased maximum cup depths were significantly associated with longer axial lengths (P < 0.001), but were not associated with spherical equivalent (P = 0.693). These associations remained only in children without tilted discs, but were no longer significant in those with tilted discs. Other HRT parameters were not associated with axial lengths or myopic status. CONCLUSIONS: Optic nerve head parameters and retinal nerve fiber layer thickness measured by the current HRT algorithms are strongly influenced by the tilting of the optic nerve head, but not by refractive errors or axial length.

Peripheral refraction and refractive error in singapore chinese 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 (≤-3 D; 14.8%), 81 with low myopia (-2.99 to -0.5 D; 32.4%), 84 with emmetropia (-0.49 to 1.0 D; 33.6%), and 47 with hyperopia (>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° (P < 0.001), but not at the nasal and temporal 15°. 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° 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.

Change in peripheral refraction over time in Singapore Chinese children.

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.

The relationship of body fatness indices and retinal vascular caliber in children.

OBJECTIVE: To examine the association between body fatness indices and retinal vascular calibre in Singapore Chinese children. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Prevalence of amblyopia and strabismus in young singaporean chinese children.

PURPOSE. To determine the prevalence of amblyopia and strabismus in young Singaporean Chinese children. METHODS. Enrolled in the study were 3009 Singaporean children, aged 6 to 72 months. All underwent complete eye examinations and cycloplegic refraction. Visual acuity (VA) was measured with a logMAR chart when possible and the Sheridan-Gardner test when not. Strabismus was defined as any manifest tropia. Unilateral amblyopia was defined as a 2-line difference between eyes with VA < 20/30 in the worse eye and with coexisting anisometropia (> or =1.00 D for hyperopia, > or =3.00 D for myopia, and > or =1.50 D for astigmatism), strabismus, or past or present visual axis obstruction. Bilateral amblyopia was defined as VA in both eyes <20/40 (in children 48-72 months) and <20/50 (<48 months), with coexisting hyperopia > or =4.00 D, myopia < or = -6.00 D, and astigmatism > or =2.50 D, or past or present visual axis obstruction. RESULTS. The amblyopia prevalence in children aged 30 to 72 months was 1.19% (95% confidence interval [CI], 0.73-1.83) with no age (P = 0.37) or sex (P = 0.22) differences. Unilateral amblyopia (0.83%) was twice as frequent as bilateral amblyopia (0.36%). The most frequent causes of amblyopia were refractive error (85%) and strabismus (15%); anisometropic astigmatism >1.50 D (42%) and isometropic astigmatism >2.50 D (29%) were frequent refractive errors. The prevalence of strabismus in children aged 6 to 72 months was 0.80% (95% CI, 0.51-1.19), with no sex (P = 0.52) or age (P = 0.08) effects. The exotropia-esotropia ratio was 7:1, with most exotropia being intermittent (63%). Of children with amblyopia, 15.0% had strabismus, whereas 12.5% of children with strabismus had amblyopia. CONCLUSIONS. The prevalence of amblyopia was similar, whereas the prevalence of strabismus was lower than in other populations.

Family history, near work, outdoor activity, and myopia in Singapore Chinese preschool children.

AIMS: To investigate the risk factors for myopia, including near work and outdoor activity, in Singapore Chinese preschool children. METHODS: A cross-sectional study, with disproportionate random sampling by 6-month age groups, of 3009 Singapore Chinese children aged 6-72 months was performed. Information on family history, near work and outdoor activity was obtained. Spherical equivalent refraction (SER) was assessed. RESULTS: Children with two myopic parents were more likely to be myopic (adjusted OR=1.91; 95% CI 1.38 to 2.63) and to have a more myopic SER (regression coefficient=-0.35; 95% CI -0.47 to -0.22) than children without myopic parents. For each 1 cm taller height, the SER was more myopic by 0.01 dioptres. Neither near work nor outdoor activity was associated with preschool myopia. CONCLUSIONS: A family history of myopia was the strongest factor associated with preschool myopia. In contrast, neither near work nor outdoor activity was found to be associated with early myopia. These data suggest that genetic factors may play a more substantial role in the development of early-onset myopia than key environmental factors.

Prevalence of refractive error in Singaporean Chinese children: the strabismus, amblyopia, and refractive error in young Singaporean Children (STARS) study.

PURPOSE: To determine the prevalence of refractive error types in Singaporean Chinese children aged 6 to 72 months. METHODS: The Strabismus, Amblyopia and Refractive Error in Singaporean Children (STARS) is a population-based study in southwest Singapore. Door-to-door recruitment of participants was used, with disproportionate random sampling in 6-month increments. Parental questionnaires were administered. Participant eye examinations included logMAR visual acuity, cycloplegic autorefraction, and ocular biometry. Overall and age-specific prevalences of myopia (spherical equivalence [SE] or= +3.00 D), astigmatism (cylinder >or= +1.50 D), and anisometropia (SE difference between each eye >or=2.00 D) were calculated. RESULTS: A total of 3009 children were examined (participation rate, 72.3%). Right eye (OD) cycloplegia data were available for 1375 boys and 1264 girls (mean age, 41 months). Mean OD SE was +0.69 D (SD 1.15). Overall myopia prevalence was 11.0% with no variance between the sexes (P = 0.91). The prevalence of high myopia (at least -6.00 D) was 0.2%. The prevalences of hyperopia, astigmatism, and anisometropia were 1.4%, 8.6%, and 0.6%, respectively. Most astigmatism (>95%) was with-the-rule (cylinder axes between 1 degrees and 15 degrees or 165 degrees and 180 degrees ). Myopia was present in 15.8%, 14.9%, 20.2%, 8.6%, 7.6%, and 6.4% of children aged 6 to 11, 12 to 23, 24 to 35, 36 to 47, 48 to 59, and 60 to 72 months, respectively. Prevalence increased with age for astigmatism (P < 0.001), but not for hyperopia or anisometropia (P = 0.55 and P = 0.37), respectively. CONCLUSIONS: The prevalences of myopia and astigmatism in young Singaporean Chinese children are high, but that of hyperopia is low. Age effects were observed for each refractive error category, but differences between the sexes were not significant. Age-related variation in myopia prevalence may be influenced by ocular development, environment, and/or testability.

Testability of vision and refraction in preschoolers: the strabismus, amblyopia, and refractive error study in singaporean children.

PURPOSE: To determine the testability of several vision and refraction tests in preschool-aged children. DESIGN: Population-based study of Chinese preschool-aged children in Singapore. METHODS: One thousand five hundred and forty-two Singaporean Chinese children aged 6 to 72 months were recruited through door-to-door screening of government-subsidized apartments in Singapore. Trained eye professionals administered all tests, including monocular logarithm of the minimum angle of resolution visual acuity with the Sheridan Gardiner chart, monocular Ishihara color testing (Richmond Products Inc, Albuquerque, New Mexico, USA), biometric measurements using IOLMaster (Carl Zeiss, Jena, Germany), and Randot stereoacuity (Stereo Optical Co, Chicago, Illinois, USA) for children 30 to younger than 72 months. Cycloplegic refraction and keratometry measurements also were determined using a table-mounted autorefractor (Canon Autorefractor RK-F1; Canon, Tokyo, Japan) in children 24 to younger than 72 months. RESULTS: Testabilities were 84.8% for visual acuity (40.7% for age 30 to < 36 months, 70.8% for age 36 to < 42 months, 86.7% for age 42 to < 48 months, 94.8 for age 48 to < 54 months, 98.6 for age 54 to < 66 months, and 98.7% for age 66 to < 72 months), 81.1% for the Ishihara color test, 82.2% for Randot stereoacuity, 62.2% for table mounted autorefraction, and 91.7% for IOLMaster. All testabilities significantly increased with age (P < .0001). Girls had higher testability rates than boys for the autorefraction and Randot stereoacuity tests (P = .036 and .008, respectively). CONCLUSIONS: The vision and refraction tests were testable in a high proportion of preschool-aged Chinese Singaporeans. Preschool children in older age groups are likely to complete these tests successfully, with important implications for determining age limits for screening in the community and clinic.