Shi-Ming Li

Design, methodology and baseline data of a school-based cohort study in Central China: the Anyang Childhood Eye Study.

Abstract Purpose: To report the design, methods and baseline data of the Anyang Childhood Eye Study (ACES), aiming to determine the prevalence, incidence and risk factors of myopia and other ocular diseases in children in central China. Methods: The ACES was a school-based cohort study conducted in Anyang city. Students have been examined and will be followed-up annually for 3–5 years. Ocular examinations included visual acuity, identification of amblyopia and strabismus, ocular biometry, optical coherence tomography, retinal photography, cycloplegic autorefraction, accommodative response, peripheral refraction, visual perception and so on. A questionnaire survey was performed to collect risk factors for myopia including near work, outdoor activity, parental myopia, birth history, habits of wearing spectacles and reading, living habits, food habits and so on. Results: Of 3112 grade 1 and 2363 grade 7 students eligible for the ACES, 2893 (93.0%) and 2267 (95.9%) participated in the study, with a mean age of 7.1 years (range 5.7–9.3 years) and 12.7 years (range 10.0–15.9 years), and proportions of male to be 57.8% and 50.0%, respectively. The prevalence rates of myopia, high myopia, emmetropia and hyperopia were 3.9%, 0.1%, 72.9% and 23.3% in grade 1, and 67.3%, 2.7%, 31.4% and 1.2% in grade 7, respectively. Similar data were found in the children confined in 6-year-old and 12-year-old ages. Conclusions: The ACES is the first large-scale cohort study in China with baseline response rates over 90%. Continuous documentation of changes and risk factors of refractive errors in these cohorts would provide new insights into myopia control in school-aged children.

Time Outdoors and Myopia Progression Over 2 Years in Chinese Children: The Anyang Childhood Eye Study.

PURPOSE To investigate whether time outdoors and a range of other activities are associated with change in spherical equivalent (SE) and axial length in Chinese children over a period of 2 years. METHODS A total of 1997 children aged 12.7 ± 0.5 (10.9-15.6) years in the Anyang Childhood Eye Study (ACES) were examined annually (baseline and two follow-up visits). Myopia was defined as cycloplegic SE < -0.50 diopters (D). Questionnaires were administered to the students and parents at baseline to gauge time spent outdoors and on other tasks. We ran mixed linear models including age, sex, and years of follow-up. RESULTS In the full cohort of children there was a suggestive association between time spent outdoors and change in axial length; however, the effect size was very small (high versus low tertile: -0.016 mm/y, P = 0.053). The association was observed in children not myopic at baseline (high versus low tertile, -0.036 mm/y; P = 0.009) but not in those already myopic at baseline (high versus low tertile: -0.005 mm/y; P = 0.595). Time outdoors and change in SE showed similar, but nonsignificant, relationships (P > 0.05), perhaps due to insufficient statistical power. The other activities examined and parental myopia were not associated with changes in SE and axial length (P > 0.11). CONCLUSIONS Within the normal range of variation encountered in these Chinese children, a wide range of activities were largely unrelated to myopia progression at this age. However, there was suggestive evidence that greater time outdoors was associated with slower axial elongation in nonmyopic teenagers, but not in existing myopes.

Atropine slows myopia progression more in Asian than white children by meta-analysis

Purpose To conduct a meta-analysis on the effects of atropine in slowing myopia progression and to compare Asian and white children and randomized controlled trials (RCTs) and observational studies. Methods Randomized controlled trials and observational studies that assessed the effects of all concentrations of atropine in slowing myopia progression in children were searched from MEDLINE, EMBASE, and the Cochrane Library up to April 2013. Jadad scoring was used to evaluate the quality of RCTs, and the Newcastle-Ottawa Scale was used for observational studies. Results Four RCTs and seven cohort studies (a kind of observational study) with 1815 children aged 5 to 15 years were included. The children had a baseline refraction of −0.50 to −9.75 diopters (D) and were followed up for 22.0 months (range, 12.0 to 36.5 months). The weighted mean differences in myopia progression in RCTs and cohort studies of Asian children were 0.55 D per year (p < 0.01) and 0.54 D per year (p < 0.001), respectively, and 0.35 D per year (p = 0.01) in cohort studies of white children. Compared with placebo, the risk of fast myopia progression (>1.0 D per year) using atropine was significantly decreased in both RCTs (odds ratio [OR], 0.14; p < 0.01) and cohort studies (OR, 0.08; p < 0.01), and the benefit of slow myopia progression (<0.50 D per year) using atropine was significantly increased in both RCTs (OR, 6.73; p < 0.01) and cohort studies (OR, 22.10; p < 0.01). Conclusions Atropine could significantly slow myopia progression in children, with greater effects in Asian than in white children. Randomized controlled trials and cohort studies provided comparable effects.

Near Work Related Parameters and Myopia in Chinese Children: the Anyang Childhood Eye Study.

Purpose To examine the associations of near work related parameters with spherical equivalent refraction and axial length in Chinese children. Methods A total of 1770 grade 7 students with mean age of 12.7 years were examined with cycloplegic autorefraction and axial length. Questions were asked regarding time spent in near work and outdoors per day, and near work related parameters. Results Multivariate models revealed the following associations with greater odds of myopia: continuous reading (> 45min), odds ratio [OR], 1.4; 95% confidence interval [CI], 1.1-1.8; close television viewing distance (≤ 3m), OR, 1.7; 95% CI, 1.2-2.3; head tilt when writing, OR, 1.3; 95% CI, 1.1-1.7, and desk lighting using fluorescent vs. incandescent lamp, OR, 1.5; 95% CI, 1.2-2.0. These factors, together with close reading distance and close nib-to-fingertip distance were significantly associated with greater myopia (P<0.01). Among near work activities, only reading more books for pleasure was significantly associated with greater myopia (P=0.03). Television viewing distance (≤ 3 m), fluorescent desk light, close reading distance (≤20 cm) and close nib-to-fingertip distance (≤ 2 cm) were significantly associated with longer axial length (P<0.01). Reading distance, desk light, and reading books for pleasure had significant interaction effects with parental myopia. Conclusions Continuous reading, close distances of reading, television viewing and nib-to-fingertip, head tilt when writing, reading more books for pleasure and use of fluorescent desk light were significantly associated with myopia in 12-year-old Chinese children, which indicates that visual behaviors and environments may be important factors mediating the effects of near work on myopia.

Retinal Nerve Fiber Layer Thickness in a Population of 12- Year-Old Children in Central China Measured by iVue-100 Spectral-Domain Optical Coherence Tomography: The Anyang Childhood Eye Study

PURPOSE To study the distribution of peripapillary retinal nerve fiber layer (RNFL) thickness in a population of 12-year-old children in central China using iVue-100 spectral-domain optical coherence tomography (SD-OCT). METHODS Twelve-year-old students (n = 2105) from four randomly selected middle schools in Anyang, China, participated in the study. Each child underwent ocular examinations, including optical biometry, cycloplegic autorefraction, and SD-OCT (iVue-100). Glaucoma optic nerve head scan was performed to measure RNFL thickness. Only the children with a signal strength index higher than 45 were included in the analyses. Multivariate analyses were performed to examine the association of RNFL with demographic variables (e.g., sex, age, and body mass index [BMI]) and ocular variables (e.g., axial length and refractive error). RESULTS Optical coherence tomography scans of adequate quality were available for 1955 children (92.9%). The mean (SD) RNFL thickness was 103.08 (9.01) μm, with the mean (SD) thickest RNFL in the inferior quadrant (129.34 [14.90] μm), followed by the superior (126.19 [15.24] μm), temporal (82.98 [10.57] μm), and nasal (73.82 [13.89] μm) quadrants. The RNFL was thicker with shorter axial length (β = -1.53, P < 0.0001) and with higher hyperopia (β = 0.90, P < 0.0001). Girls had slightly thicker average RNFL thickness than boys (P < 0.0001). The RNFL thickness had no significant correlation with age or BMI. CONCLUSIONS This study establishes normative peripapillary RNFL values of 12-year-old Chinese children as measured by iVue-100 SD-OCT. The RNFL thickness decreased significantly with increasing axial length and higher myopia.

Efficacy, Safety and Acceptability of Orthokeratology on Slowing Axial Elongation in Myopic Children by Meta-Analysis

Abstract Purpose: To compare the efficacy, safety and acceptability of a treatment group (Orthokeratology) to a control group (single vision Spectacles) on slowing axial elongation in children. Methods: We searched studies in MEDLINE, EMBASE and the Cochrane Library up to January 2015 for randomized controlled trials (RCTs) and observational studies. We pooled the mean differences between the Orthokeratology and Control groups for axial elongation and the OR for rates of adverse events and dropout. Results: Three RCTs and six cohort studies with 667 children aged 6–16 years old were included. Two years’ mean differences in axial elongation were −0.27 mm (95% confidence intervals [CI], −0.32 to −0.23) in all studies, −0.28 mm (95% CI, −0.35 to −0.20) in RCTs and −0.27 mm (95% CI, −0.32 to −0.22) in cohort studies (p < 0.01). At 6 months, 1 year, 1.5 years and 2 years, mean differences in axial elongation were −0.13 mm, −0.19 mm, −0.23 mm, and −0.27 mm (p < 0.01), respectively. The effect was greater in Asian children than Caucasian (−0.28 mm versus −0.22 mm) and in children with moderate to high myopia when compared to children with low myopia (−0.35 mm versus −0.25 mm). Orthokeratology had more non-significant adverse events (odd ratio [OR], 8.87; 95% CI, 3.79–20.74; p < 0.01) but comparable dropout rates (OR = 0.84, 95% CI, 0.40–1.74, p = 0.64) than control. Conclusion: Orthokeratology has significantly greater efficacy in controlling axial elongation in children compared to Spectacle correction. The safety and acceptability results are good, and there appears to be a greater myopia control effect in Chinese children compared to Caucasians, and in those with higher initial myopia.

Distribution of ocular biometry in 7- and 14-year-old Chinese children.

Purpose To describe distributions of ocular biometry and their associations with refraction in 7- and 14-year-old children in urban areas of Anyang, central China. Methods A total of 2271 grade 1 students aged 7.1 ± 0.4 years and 1786 grade 8 students aged 13.7 ± 0.5 years were measured with ocular biometry and cycloplegic refraction. A parental myopia questionnaire was administered to parents. Results Mean axial length, anterior chamber depth, lens thickness, central corneal thickness, corneal diameter, corneal radius of curvature, axial length/corneal radius of curvature ratio, and spherical equivalent refraction were 22.72 ± 0.76 mm, 2.89 ± 0.24 mm, 3.61 ± 0.19 mm, 540.5 ± 31 &mgr;m, 12.06 ± 0.44 mm, 7.80 ± 0.25 mm, 2.91 ± 0.08, and +0.95 ± 1.05 diopters (D), respectively, in 7-year-old children. They were 24.39 ± 1.13 mm, 3.42 ± 0.41 mm, 3.18 ± 0.24 mm, 548.9 ± 33 &mgr;m, 12.03 ± 0.43 mm, 7.80 ± 0.26 mm, 3.13 ± 0.14, and −2.06 ± 2.20 D, respectively, in 14-year-old children. Compared with 7-year-old children, the older group had significantly more myopia (−3.0 D), longer axial length (1.7 mm), deeper anterior chamber depth (0.3 mm), thinner lens thickness (−0.2 mm), thicker central corneal thickness (10 &mgr;m), and greater axial length/corneal radius of curvature ratio (0.22) (all p < 0.001), as well as smaller corneal diameter (−0.03 mm, p = 0.02) and similar corneal radius of curvature. Sex differences were similar in both age groups, with boys having longer axial length (0.5 mm), deeper anterior chamber depth (0.1 mm), shorter lens thickness (0.03 mm), greater central corneal thickness (5 &mgr;m), greater corneal diameter (0.15 mm), and greater corneal radius of curvature (0.14 mm) than girls (all p < 0.01). The most important variables related to spherical equivalent refraction were vitreous length, corneal radius of curvature, and lens thickness. Conclusions The 14-year-old group had larger parameter dimensions than the 7-year-old group except for corneal radius of curvature (unchanged) and lens thickness and corneal diameter (both smaller). Boys had large parameter dimensions than girls except for lens thickness (smaller). Axial length, corneal radius of curvature, and lens thickness were the most important determinants of refraction.

Peripheral refraction in 7- and 14-year-old children in central China: the Anyang Childhood Eye Study

Purpose To determine the distribution of peripheral refraction, including astigmatism, in 7- and 14-year-old Chinese children. Methods 2134 7-year-old and 1780 14-year-old children were measured with cycloplegic central and horizontal peripheral refraction (15° and 30° at temporal and nasal visual fields). Results 7- and 14-year-old children included 9 and 594, respectively, with moderate and high myopia (≤−3.0 D), 259 and 831 with low myopia (−2.99 to −0.5 D), 1207 and 305 with emmetropia (−0.49 to +1.0 D), and 659 and 50 with hyperopia (>1.0 D), respectively. Myopic children had relative peripheral hyperopia while hyperopic and emmetropic children had relative peripheral myopia, with greater changes in relative peripheral refraction occurring in the nasal than the temporal visual field. The older group had the greater relative peripheral hyperopia and higher peripheral J180. Both age groups showed positive slopes of J45 across the visual field, with greater slopes in the older group. Conclusions Myopic children in mainland China have relative peripheral hyperopia while hyperopic and emmetropic children have relative peripheral myopia. Significant differences exist between 7- and 14-year-old children, with the latter showing more relative peripheral hyperopia, greater rate of change in J45 across the visual field, and higher peripheral J180.

Full correction and Undercorrection of Myopia Evaluation Trial: design and baseline data of a randomized, controlled, double-blind trial

To determine the difference in the rate of myopic progression between children wearing single vision lenses with undercorrection of +0.50 D and children whose myopia is fully corrected, and to explore the factors that may influence the process.

Corneal Power, Anterior Segment Length and Lens Power in 14-year-old Chinese Children: the Anyang Childhood Eye Study

To analyze the components of young Chinese eyes with special attention to differences in corneal power, anterior segment length and lens power. Cycloplegic refractions and ocular biometry with LENSTAR were used to calculate lens power with Bennett’s method. Mean refraction and mean values for the ocular components of five different refractive groups were studied with ANOVA and post-hoc Scheffé tests. There were 1889 subjects included with full data of refraction and ocular components. As expected, mean axial length was significantly longer in myopic eyes compared to emmetropes. Girls had steeper corneas, more powerful lenses and shorter eyes than boys. Lens power was lower in boys and also lower in myopic eyes. Lens thickness was the same for both genders but was lower in myopic eyes. Although cornea was steeper in myopic eyes in the whole sample, this was a gender effect (more girls in the myopic group) as this difference disappeared when the analysis was split by gender. Anterior segment length was longer in myopic eyes. In conclusion, myopic eyes have lower lens power and longer anterior segment length, that partially compensate their longer axial length. When analyzed by gender, the corneal power is not greater in low and moderate myopic eyes.