Peripapillary retinal nerve fibre layer thickness and its association with refractive error in Chinese children: the Anyang Childhood Eye Study.

BACKGROUND: To report the thickness of the peripapillary retinal nerve fibre layer (pRNFL) in Chinese children and examine its association with refractive error, axial length (AL) and optic disc parameters. DESIGN: Population-based cross-sectional study. PARTICIPANTS: A total of 2893 seven-year-old children from 11 randomly selected primary schools in Anyang, central China. METHODS: Participants underwent ophthalmic examinations including optical biometry, cycloplegic autorefraction and spectral-domain ocular coherence tomography. MAIN OUTCOME MEASURES: Retinal nerve fibre layer thickness in 16 radial sections, cycloplegic spherical equivalent, AL. RESULTS: The mean (SD) average RNFL thickness was 102.01(8.02) µm. The average RNFL thickness decreased with smaller disc area (r = 0.18, R2 = 0.03, P < 0.0001), bigger cup area (r = -0.11, R2 = 0.01, P < 0.0001), smaller rim area (r = 0.28, R2 = 0.08, P < 0.0001), smaller nerve head volume (r = 0.27, R2 = 0.07, P < 0.0001), longer AL (r = -0.15, R2 = 0.02, P < 0.0001) and a negative spherical equivalent (r = 0.11, R2 = 0.01, P < 0.0001). Hyperopic children had a thicker RNFL than emmetropic children [102.45(8.13) µm vs. 100.81 (7.18) µm, P < 0.001]. Myopic children had thinner RNFL than emmetropic children [99.17 (7.69) µm vs. 100.81 (7.18) µm, P < 0.05]. CONCLUSION: Retinal nerve fibre layer thickness decreased with increasing AL, higher myopia, bigger cup area, smaller disc and rim area, and a smaller nerve head volume, but the coefficient of determination for all these associations was small. The RNFL in myopes was significantly thinner than emmetropes or hyperopes, but with small absolute differences. The study provides RNFL values for healthy 7-year-old Chinese children. Follow up of this cohort to observe the change of RNFL thickness with myopia and possible change in detected associations with age is planned.

Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES).

PURPOSE: To determine the prevalence of amblyopia and strabismus in 7th-grade junior high school students in central China. METHODS: Using stratified cluster sampling, 2363 7th-grade students were recruited from four junior high schools in Anyang city into the cross-sectional Anyang Childhood Eye Study (ACES). All students underwent visual acuity (VA), cycloplegic autorefraction, cover test, and ocular movement examinations. Uncorrected VA and best-corrected VA (BCVA) were measured with a logarithm of the minimum angle of resolution (logMAR) chart. Cycloplegic autorefraction was performed after administration of 1.0% cyclopentolate and Mydrin-P. Strabismus was defined as heterotropia at near or distance fixation. Amblyopia was defined as BCVA ≤ 0.1 logMAR units in one or both eyes, without ocular pathology in either eye. RESULTS: Of the 2363 eligible students, 2260 (95.6%) completed all examinations. The mean age of the students was 12.4 ± 0.6 years. Amblyopia was present in 52 students (2.5%), of whom 33 (63.5%) had unilateral and 19 (36.6%) had bilateral amblyopia. Of those with unilateral amblyopia, 18 (54.5 %) had anisometropia and 7 (21.2%) had strabismus. Of those with bilateral amblyopia, 6 (31.6%) had significant refractive error. Strabismus was present in 108 students (5.0%), of whom 2 (1.9%) had esotropia, 102 (94.4%) had exotropia, 3 (2.8%) had vertical strabismus, and 1 (0.9%) had microstrabismus. Of the 108 students with strabismus, 9 (8.3%) had amblyopia. CONCLUSION: The cross-sectional ACES which examined the prevalence of amblyopia and strabismus in 7th-grade students in central China revealed the prevalence of strabismus, particularly the proportion of exotropia, to be higher than previously reported.

Prevalence, causes and associations of amblyopia in year 1 students in Central China : The Anyang childhood eye study (ACES).

BACKGROUND: Earlier diagnosis and treatment of amblyopia are associated with improved visual outcomes. This study reports the prevalence of amblyopia and associated factors in year 1 primary school students in central China. METHODS: The school-based, cross-sectional study involved 3,112 year 1 primary school students . All the participants underwent a comprehensive eye examinations including cycloplegic refraction, cover test and ocular movement examinations. The unaided and best corrected visual acuity (BCVA) was recorded. Unilateral amblyopia was defined as a 2-line interocular difference with BCVA ≤ 20/32 (≥ logMar 0.2) in the worse eye and with coexisting anisometropia (≥ 1.00 D SE for hyperopia, ≥ 3.00 D SE for myopia, or ≥ 1.50 D for astigmatism), strabismus or past or present visual axis obstruction. Bilateral amblyopia was defined as BCVA in both eyes<20/40 (> logMar 0.3), with coexisting hyperopia ≥ 4 D SE, myopia ≤ -6 D SE, or astigmatism ≥ 2.5 D, or past or present visual axis obstruction. RESULTS: Out of the 3,112 eligible students, 2,893 (93.0 %) students completed the examinations. The average age of the students was 7.1 ± 0.4 (mean ± standard deviation SD) years old. The prevalence of amblyopia was 1.0 % (95 % confidence interval [CI], 0.6 %-1.3 %) with no difference between the sexes (P = 0.88). Of the 27 amblyopic students, unilateral amblyopia was found in 18 (66.7 %) students, and bilateral amblyopia in 9 (33.3 %) students. Of 18 unilateral amblyopia, 13 were anisometropic amblyopia, 4 were strabismus amblyopia, 1 was mixed amblyopia. Of 9 bilateral amblyopia, 7 were isoametropic amblyopia, 2 were stimulus deprivation. The mean corrected VA of the amblyopic eyes was 30.50 logMAR letters (Snellen VA equivalent 4/12.6), and the range was 5 to 45 logMAR letters (Snellen VA equivalent 4/40-4/6.3). Most amblyopic eyes (38.9 %) were significantly hyperopic (spherical equivalent ≥ +3.00 D); 25.0 % were myopic. In addition, 58 (2.1 %) students had a previous amblyopia history of amblyopia that was not corroborated in this study. CONCLUSIONS: The study shows a relatively low prevalence of amblyopia (1.0 %) in year 1 students in central China. Amblyopia is usually caused by abnormal refractive error.

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 (ß = -1.53, P < 0.0001) and with higher hyperopia (ß = 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.

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

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.

Screening for amblyopia among grade-1 students in primary school with uncorrected vision and stereopsis test in central China.

BACKGROUND: Screening for amblyopia at earliest is important for early treatment and better prognosis. This study aimed to evaluate the validity of uncorrected distant and near visual acuity (VA) and stereoacuity for screening amblyopia in grade-1 students in primary school in central China. METHODS: By stratified cluster sampling, 3112 grade-1 students from 11 Anyang primary schools were selected for the study. All the participants underwent uncorrected distant and near VA, stereopsis test, cycloplegic refraction, best corrected VA (BCVA), cover test, and ocular movement examination. VA was measured with a logarithm of the minimum angle of resolution (logMAR) chart. Stereoacuity was measured with the Lang II stereo card and TNO test. Amblyopia was defined as the BCVA less than or equal to 0.1 logMAR units of any eye in the absence of significant pathological abnormalities. The sensitivity, specificity, and positive and negative predictive value of uncorrected VA and stereoacuity for amblyopia were analyzed. RESULTS: Out of the 3112 eligible students, 2893 (92.96%) completed the examinations. The average age of the students was (7.10 ± 0.41) years. Screened by distant VA with low cutoff (logMAR 0.1), high cutoff (logMAR 0.0), and near VA (logMAR 0.0), 31.64%, 73.18%, and 50.23% students were abnormal, respectively. Screened by stereopsis test, only 4.69% students were abnormal. Diagnosed by a senior pediatric ophthalmologist, 61 students had amblyopia. The sensitivities of distant VA with low/high cutoff and near VA were 92.31%, 100%, and 80.77%, respectively, whereas that of stereoacuity by TNO test was 15.38%. Simultaneous testing of either two of the three tests improved the sensitivity. CONCLUSIONS: Distant VA test of high cutoff alone displays a high sensitivity but a low specificity. Simultaneous testing of distant VA of low cutoff and stereoacuity is a better choice to balance between sensitivity and specificity.