Normative visual acuity in Chinese preschoolers aged 36 to <48 months as measured with the linear HOTV chart: the Yuhuatai Pediatric Eye Disease Study

Longitudinal change in components of astigmatism and its association with axial length-corneal radius ratio in Chinese young children: the Nanjing Eye Study

PURPOSE

To assess the longitudinal change in components of astigmatism from age 4 to 7 years and its association with axial length-corneal radius ratio (AL/CR).

METHODS

Children born between September 2011 and August 2012 in Yuhuatai District of Nanjing were invited to participate in the Nanjing Eye Study for a comprehensive eye examination annually since 2015. The data presented in this paper were obtained in 2016, 2017, and 2019. At each study encounter, noncycloplegic autorefraction and ocular biometric parameters were measured. Changes of total astigmatism (TA), corneal astigmatism (CA), anterior corneal astigmatism (ACA), residual astigmatism (RA), and internal astigmatism (IA) were analyzed in clinical notation (Cyl) and vector notation (J₀, J₄₅).

RESULTS

Nine hundred fifty-four children (mean ± standard deviation of baseline age: 4.63 ± 0.29 years, 53.7% boys) had complete data and were included in this study. Mean slopes of longitudinal changes in Cyl notation were significantly negative for TA, CA, and ACA, but positive for IA. TA, CA, ACA, and RA of J₀ notation had a shift toward increasing with-the-rule (WTR) astigmatism and/or decreasing against-the-rule (ATR) astigmatism. TA of J₄₅ notation showed an increase in astigmatism at axis 135° and/or a decrease in astigmatism at axis 45°, while CA and ACA of J₄₅ notation showed an opposite change. Longitudinal changes in ACA and IA were negatively correlated in J₀ notation, but not in J₄₅ notation. Based on compensation factor (CF, defined as the minus ratio of IA and ACA), the compensation proportions for J₀ in varying degrees (CF: 0.1-2) in 2016, 2017, and 2019 were 91.3%, 93.5%, and 90.0%, respectively, while these for J₄₅ were 74.9%, 76.5%, and 34.6%, respectively. Higher AL/CR increase was associated with less decrease or more increase in CA and ACA of Cyl notation, and a shift toward increasing WTR and/or decreasing ATR in these of J₀ notation.

CONCLUSIONS

The compensatory role of IA was persistent and prominent from 4 to 7 years old for J₀ notation in Chinese young children. The progression of AL/CR was correlated with astigmatism originated from the cornea.

Effect of birth order on stereoacuity in Chinese preschool children: a cross-sectional study

OBJECTIVE

This study aimed to investigate the relationship between birth order and stereoacuity among Chinese children aged 60-72 months.

DESIGN

Cross-sectional.

PARTICIPANTS

1342 children with complete data on the questionnaire, stereoacuity and refraction were included.

RESULTS

The mean stereoacuity was 53.2±1.7, 56.9±1.9 and 60.9±1.5 s of arc in the first-born group, second-born group and third-born group, respectively. Lower birth order was significantly correlated with better stereoacuity (p=0.036). Third-borns (OR=3.02, p=0.027) were at higher risk of having subnormal stereoacuity compared with first-borns in the multivariate analysis.

CONCLUSION

Later-borns had poorer stereoacuity than first-borns.

Prevalence, causes and risk factors of reduced VA and persistent reduced VA among preschool children in Eastern China

AIMS

To determine prevalence, causes, and risk factors of reduced uncorrected visual acuity (UCVA), reduced presenting visual acuity (PVA), and persistent reduced visual acuity (VA) among Chinese preschool children.

METHODS

The longitudinal, population-based Nanjing Eye Study (NES) was carried out. Children underwent baseline comprehensive ocular examinations in 2016 (at 48-60 months old) and the follow-up ocular examinations in 2017. A comprehensive questionnaire about children and their families was completed by their legal guardians. For children having reduced PVA at baseline, a follow-up questionnaire about potential factors concerning VA correction was completed. Reduced VA was defined as VA worse than 0.30 logMAR (Snellen equivalent 6/12, 20/40), and persistent reduced VA was defined as reduced PVA in both 2016 and 2017.

RESULTS

Among 1448 participants with both eye examinations and questionnaires completed, prevalence of reduced UCVA, reduced PVA, and persistent reduced VA at age of 60-72 months were 5.94%, 3.04%, and 1.59% respectively. Causes for reduced PVA were refractive error (79.5%), amblyopia (18.2%), and amblyopia combined nystagmus (2.3%). Among 23 children having persistent reduced VA, causes of reduced PVA remained unchanged in 13 children and 4 children developed amblyopia from refractive error. Younger age (OR = 1.09 for each month decrease, p = 0.01) and non-breastfeeding (OR = 2.08, p = 0.03) were risk factors for reduced UCVA. Younger children with reduced UCVA were at higher risk of having reduced PVA (OR = 1.18 for each month decrease, p = 0.04). Children with siblings (OR = 5.95, p = 0.02) were more likely to have persistent reduced VA.

CONCLUSIONS

Future vision health promotion strategies among preschool children should focus on early vision-screening and timely refractive correction. Apart from children of non-breastfeeding mothers, attention should also be paid to children with siblings.

Risk factors for astigmatic components and internal compensation: the Nanjing Eye Study

Purpose

To determine the risk factors for total astigmatism (TA), anterior corneal astigmatism (ACA), and internal compensation in Chinese preschool children.

Methods

In the population-based Nanjing Eye Study, children were measured for noncycloplegic refractive error and for biometric parameters. Data from questionnaires and measures from right eyes were analyzed for determining risk factors for TA, ACA, and internal compensation from multivariate logistic regression models.

Results

Of 1327 children (66.8 ± 3.4 months, 53.2% male), older age of the child (OR = 0.95 for per month increase; P = 0.03), older paternal age at child birth (OR = 1.04 for per year increase; P = 0.03), paternal astigmatism (OR = 1.89; P = 0.003), maternal astigmatism (OR = 1.73, P = 0.008), and second-hand smoke exposure during pregnancy (OR = 1.64; P = 0.03) were associated with higher risk of TA, while partial breastfeeding (OR = 0.49, P = 0.006) or formula feeding (OR = 0.46, P = 0.003) were associated with lower risk of TA. Larger ratio of axial length to corneal radius (OR = 16.16 for per unit increase; P = 0.001), maternal working during pregnancy (OR = 1.27; P = 0.04), and cesarean delivery (OR = 1.68, P = 0.04) were associated with higher risk of ACA, while formula feeding was associated with lower risk of ACA (OR = 0.57, P = 0.01). Paternal astigmatism (OR = 0.50, P = 0.01) and assisted reproduction (OR = 0.56, P = 0.03) were associated with lower risk of horizontal or vertical internal compensation. More outdoor activity time (OR = 1.15 for per hour increase, P = 0.01) was associated with higher risk of oblique internal compensation while more nighttime sleep on weekends (OR = 0.83 for per hour increase, P = 0.01) was associated with lower risk of oblique internal compensation.

Conclusions

Our study confirmed some previously reported risk factors and identified some novel risk factors for astigmatism including formula feeding for lower risk of both ACA and TA, and older paternal age at child birth for higher risk of TA.

Preschool Children Exhibit Evident Compensatory Role of Internal Astigmatism in Distribution of Astigmatism: The Nanjing Eye Study

Purpose

To determine the prevalence and associated risk factors for total, corneal, and residual astigmatism and to evaluate the relations between components of astigmatism in Chinese preschool children.

Methods

In the population-based, cross-sectional Nanjing Eye Study, children were measured for noncycloplegic refractive error using an autorefractor and for biometric parameters using an optical low-coherent reflectometry. Data from right eyes were analyzed to calculate the prevalence of astigmatism using various cutpoints (0.5, 1.0, and 1.5 diopters [D]) and for determining risk factors using logistic regression models. Relations between astigmatism components were assessed using Spearman correlation coefficients (ρ).

Results

Of 1817 children (mean ± SD of age: 54.8 ± 3.5 months, 54.2% male), the median (1st and 3rd quartile) of total, corneal, and residual astigmatism (vectorial difference between total and corneal astigmatism) was -0.25 (-0.50, 0), -1.06 (-1.49, -0.72), and -0.92 (-1.23, -0.62) D and their prevalence rate 1.0 D or more was 14.2%, 56.1%, and 44.2%, respectively. With-the-rule was the most common type in total astigmatism (75.2%) and in corneal astigmatism (88.2%) while against-the-rule was predominant in residual astigmatism (75.6%). A negative correlation was found between corneal J0 and internal J0 (ρ = -0.74, P < 0.001) and between corneal J45 and internal J45 (ρ = -0.87, P < 0.001). Based on compensation factor (CF), defined as the minus ratio of internal astigmatism (vectorial difference between total and anterior corneal astigmatism) and anterior corneal astigmatism, internal J0 compensated for total J0 in varying degrees (CF: 0.1-2) in 91.5% cases, while that percentage for J45 component was 77.2%. In univariate logistic regression model, older age was significantly associated with total astigmatism (odds ratio [OR] = 0.96 for per-month increase, P = 0.03), and larger axial length-corneal radius ratio was significantly associated with higher risk of residual astigmatism (OR = 2.28 for per unit increase, P = 0.03).

Conclusions

The compensatory role of internal astigmatism on reducing corneal astigmatism was prominent in preschool children. Larger axial length-corneal radius ratio was significantly associated with higher risk of residual astigmatism.

Stereoacuity and Related Factors in Healthy Preschool Children: The Nanjing Eye Study

Purpose: To assess the distribution of stereoacuity and related factors in healthy preschool children aged 48-60 months in eastern China. Methods: This cross-sectional study was part of the Nanjing Eye Study, a longitudinal population-based cohort study. In 2016, preschool children without any neurological problems or ophthalmological abnormalities completed comprehensive eye examinations, including visual acuity, ocular alignment and movements, cycloplegic refraction, axial length, interpupillary distance, Titmus stereotest, anterior segment, and fundus examination. Multivariate linear regression model was used to determine the factors associated with stereoacuity score, and logistic regression model was used to determine the factors associated with subnormal stereoacuity (worse than 40 arc-seconds). Results: Among 942 healthy preschool children (mean age = 55 months), the mean (SD) stereoacuity was 81 (2.3) arc-seconds with majority (76.5%) worse than 40 arc-seconds. In the multivariate analysis, older age (p = 0.001) and better presenting visual acuity (PVA) (p = 0.01) were independently associated with better stereoacuity score. Older age was also associated with low risk of subnormal stereoacuity (odds ratio = 0.37,p < 0.001 for age 57-60 months compared to age 48-51 months). Conclusions: The maturation of stereopsis has not completed by the age of 48-60 months. Age and PVA should be taken into account when evaluating stereopsis in healthy preschoolers. The significant associations of age and PVA with stereoacuity provide valuable insights into possible intervention for healthy preschool children with poor stereoacuity.

Prevalence of reduced visual acuity among preschool children in eastern China and comparison at a 5-year interval

IMPORTANCE

Assessing the prevalence of reduced visual acuity and its change over time has significant public health importance. This study evaluated prevalence of reduce visual acuity in children aged 48-60 months, and compared it with previous data.

BACKGROUND

Previous studies reported prevalence of reduced visual acuity in preschool children, but none has evaluated prevalence change in the same area.

DESIGN

Nanjing Eye Study, a longitudinal population-based study.

PARTICIPANTS

Two thousand three hundred eligible children.

METHODS

Comprehensive eye examinations.

MAIN OUTCOME MEASURES

Uncorrected visual acuity, presenting visual acuity, best-corrected visual acuity, anterior segment and fundus examination, cycloplegic refraction.

RESULTS

Based on the worse and better eye, respectively, 6.8% and 3.5% had reduced uncorrected visual acuity and 4.0% and 1.4% had reduced presenting visual acuity. Compared to rates in the Nanjing Paediatric Vision Project carried out 5 years ago in the same area, the prevalence rates of reduced uncorrected visual acuity were significantly higher (6.8% vs. 5.3%, P = 0.04 for worse eye; 3.5% vs. 2.1%, P = 0.0049 for better eye), but there was no significant increase in rates of reduced presenting visual acuity (4.0% vs. 3.7%, P = 0.63 for better eye; 1.4% vs. 1.7%, P = 0.43 for worse eye). The prevalence rate of glasses prescription is higher in this study (4.5% vs. 3.1%, P = 0.02).

CONCLUSIONS AND RELEVANCE

Prevalence of reduced uncorrected visual acuity increased significantly, indicating that Chinese children are faced with more vision-threatening factors. However, more children with refractive errors got appropriate correction.