Astigmatism and its components in 12-year-old Chinese children: the Anyang Childhood Eye Study

Internal astigmatism and risk factors in Tibetan schoolchildren: The Lhasa Childhood Eye Study

SIGNIFICANCE

The study first investigated the prevalence and internal relationship of astigmatism components under cycloplegia in Tibetan children on plateau areas of China. We found a higher prevalence of refractive (RA) and corneal astigmatism (CA) in Lhasa children and certified the compensation of internal astigmatism (IA), which might be associated with myopic progression.

PURPOSE

This study aimed to investigate the prevalence and related risk factors of RA, CA, and IA and evaluate compensation and associated influence factors of IA in Lhasa Tibetan children.

METHODS

This was a school-based cross-sectional study. Stratified random clustering was used to recruit 1751 Tibetan children with a mean age of 7.90 ± 0.48 years from schools in Lhasa, China. Cycloplegic autorefraction was conducted, and ocular biometrics were examined.

RESULTS

The prevalence rates of RA, CA, and IA were 18.73, 72.53, and 40.72%, respectively, with the diagnosis criteria ≥1.00 D. With-the-rule was the main type of RA (70.05%) and CA (91.93%), whereas the against-the-rule was predominant in IA (79.67%). Compared with the reference group (spherical equivalent range, 0.51 to 1.00 D), mean RA and CA increased with more hyperopic and myopic refractions, and mean IA was significantly lower only in myopia and emmetropia groups. Girls had a higher incidence of CA and IA than boys. Internal astigmatism was negatively correlated with CA in the vertical/horizontal vector (J0) and oblique vector (J45). The majority of IA compensated for RA in different degrees (95.25% in J0 and 66.43% in J45) and no compensation accounted for a higher proportion in myopic children (10.47% in J0 and 5.76% in J45).

CONCLUSIONS

The prevalence of RA and CA in Tibetan children from Lhasa was higher than reported in most previous studies. The compensation of IA in reducing CA was prominent, and the function could decrease with the myopic progression.

Association between insufficient sleep and astigmatism in preschool children

The aim of this study is to examine the association between insufficient sleep and astigmatism, as well as its related refractive components, in preschool children. Preschool children aged 3 to 6 from two kindergartens in Shanghai participated in this study. Non-cycloplegic refraction was assessed using an auto-refractor (Topcon KR-800, Tokyo, Japan), and biometric parameters were measured with the IOL Master 700 (Carl Zeiss, Jena, Germany). Sleep duration and lifestyle information were collected via questionnaires. Total Astigmatism (TA), Anterior Corneal Astigmatism (ACA), Internal Astigmatism (IA), and Compensation Factor (CF) were calculated from vector components J0 and J45. A total of 451 preschool children (55% males, mean age 5.20 ± 0.84 years) were included, with 5.8% experiencing astigmatism. Insufficient sleep was associated with higher astigmatism prevalence (OR = 2.932, 95% CI: 1.121 to 7.669) and increased cylinder power (β = 0.155, 95% CI: 0.024 to 0.286). Total sleep duration showed an inverse association with cylinder power (β = -0.049, 95% CI: -0.092 to -0.007). Insufficient sleep correlated significantly with J0t (β = 0.123, 95% CI: 0.032-0.215) and J0i (β = 0.170, 95% CI: 0.072-0.269), and CF0 (Adjusted OR = 1.731, 95% CI: 1.005 - 2.981). Sleep duration was also significantly associated with J0t, J0i and CF0. Insufficient sleep is significantly associated with astigmatism in preschool children, primarily through internal astigmatism. These findings emphasize the need for vision screening in children with insufficient sleep to identify and address refractive issues early. What is Known: • Refractive errors, including astigmatism, are common in preschool children and influenced by both environmental and genetic factors. • Insufficient sleep is significantly associated with refractive errors, particularly myopia, and is known to affect visual health and ocular conditions. What is New: • Insufficient sleep is significantly associated with astigmatism in preschool children. • This association may primarily stem from internal compensation mechanisms.

Prevalence and risk factors for astigmatism in 7 to 19-year-old students in Xinjiang, China: a cross-sectional study

BACKGROUND

To investigate the prevalence and risk factors for astigmatism in 7-19-year-old students in Xinjiang, China.

METHODS

A school-based, cross-sectional study was conducted on students who underwent refraction examination in Xinjiang, China, between May and December 2019. The prevalence of astigmatism was determined. Astigmatism was defined as cylinder power (C) ≤-0.75 D, undefined astigmatism as ≤-1.50 D, and high astigmatism as C ≤-3.00 D. Astigmatism types were: against-the-rule astigmatism (maximum refraction of the main meridian in 180° ± 30°), with-the-rule astigmatism (maximum refraction of the main meridian at 90°±30°), and oblique astigmatism (all other cases).

RESULTS

Of the 71,838 students examined (51.0% boys, 7 - 19 years old), 25,945 (36.1%, 95%CI: 35.52-36.68%) had astigmatism and 1267 (1.8%, 95%CI: 1.07-2.53%) had high astigmatism. The prevalence of astigmatism was greater in Han individuals (39.6%) compared with the Hui (34.0%), Kazakh (34.0%), Kyrgyz (32.1%), and Uyghur (26.4%) populations. Among the 25,945 students with astigmatism, 19,947 had with-the-rule astigmatism (76.9%), 3405 had against-the-rule astigmatism (13.1%), and 2593 had oblique astigmatism (10.0%). Multivariable logistic regression analysis showed that ethnicity (Han individuals more susceptible), male gender, age, and refractive errors (myopia and hyperopia) were independently associated with astigmatism, high astigmatism, and with-the-rule astigmatism (all P < 0.05).

CONCLUSIONS

The prevalence of astigmatism among children and adolescents in Xinjiang was 36.1%, including 1.8% of high astigmatism. In this population, astigmatism was mainly of the with-the-rule astigmatism type (76.9%). Han ethnicity, male gender, and myopia or hyperopia were independently associated with a high risk of astigmatism.

Refractive and corneal astigmatism in Chinese 4-15 years old children: prevalence and risk factors

BACKGROUND

To investigate the prevalence and risk factors of refractive astigmatism (RA) and corneal astigmatism (CA) in preschool children and school-aged children in Shanghai, China.

METHODS

In this school-based, cross-sectional study, 4-15 years old children across three learning stages of kindergarten, primary school, and junior high school underwent noncycloplegic autorefraction and completed comprehensive questionnaires involving time spent on daily homework and outdoor activities. Data from the right eyes were analysed.

RESULTS

Overall, 7084 children (mean ± standard deviation (SD) of age: 8.08 ± 3.11 years) were included, and the prevalence rates of RA/CA ( ≤ - 1.0 D) in children were 15.8%/64% in kindergartens, 16.5%/65% in primary schools, and 32.8%/76.9% in junior high schools. The magnitude and prevalence of RA and CA all increased with age or with learning stage (all P < 0.001). The presence of RA was associated with more myopic spherical power (odds ratio (OR) 0.956, P = 0.021), junior high school (OR 1.973, P < 0.001), longer homework time on weekdays (OR 1.074, P = 0.029), and shorter outdoor activity time on weekends (odds ratio 0.929, P = 0.013).

CONCLUSION

In the wide age range of 4 to 15 years, the magnitude and prevalence of RA and CA increased with the learning stage, and these increases mainly began at the primary school stage. Factors, including longer homework time and shorter outdoor time were correlated with the presence of RA.

Effects of atropine 0.01% on refractive errors in children with myopia

Background

Little is known about changes in astigmatism during atropine treatment. We aimed to explore the effects of atropine 0.01% eye drops on both spherical and cylindrical refractive errors in myopic children.

Methods

Children aged 6-14 years with myopia ≥ -6.00 D and < -0.50 D, and total astigmatism > -2.00 D in at least one eye were enrolled. Subjects were randomised either to receive atropine 0.01% once nightly with single-vision lenses or simply to wear single-vision lenses and were followed up at 3-month intervals. Cycloplegic refraction and axial length were measured. The magnitude and direction of total astigmatism (TA), corneal astigmatism (CA), and residual astigmatism (RA) were evaluated.

Results

Overall, 119 eyes (69 eyes in the atropine group and 50 eyes in the control group) were included in the final analyses after 9 months. Atropine-treated eyes showed significantly less progression of myopia than did control eyes (spherical equivalent: -0.35 ± 0.33 vs. -0.56 ± 0.49 D, p = 0.001; axial length: 0.20 ± 0.19 vs. 0.33 ± 0.19 mm, p < 0.001). Compared with control eyes (-0.04 ± 0.23 D), a significant increase in TA was observed in the atropine-treated eyes (-0.14 ± 0.29 D); this was mainly attributed to the increase in CA (-0.17 ± 0.26 D) rather than the minor decrease in RA (0.02 ± 0.32 D).

Conclusions

Atropine 0.01% was effective in preventing myopia progression, whereas 9 months of atropine treatment resulted in a clinically small, but statistically significant increase in TA in myopic Chinese children.

Correlation between ocular residual astigmatism and anterior corneal astigmatism in children with low and moderate myopia

BACKGROUND

To assess the correlation between ocular residual astigmatism and anterior corneal astigmatism in children with low and moderate myopia.

METHODS

Refractive astigmatism was determined by subjective manifest refraction. Anterior corneal astigmatism was determined by IOL Master. Thibos vector analysis was used to calculate ocular residual astigmatism. Correlation analysis was used to assess the relationship between the amounts of ocular residual astigmatism and anterior corneal astigmatism. The relationship between the vectors of ocular residual astigmatism and anterior corneal astigmatism was evaluated by a physical method.

RESULTS

The study analysed 241 right eyes of 241 children aged 8 to 18 years old. In this study, the median magnitude of ocular residual astigmatism was 1.02 D, with an interquartile range was of 0.58 D. Against-the-rule ocular residual astigmatism was seen in 232 eyes (96.3%). There was a significant and moderate correlation between ocular residual astigmatism and anterior corneal astigmatism (r = 0.50, P < 0.001). Ocular residual astigmatism compensated for anterior corneal astigmatism in 240 eyes (99.6%). The mean compensation value was 1.00 ± 0.41 D (range 0.02 D to 2.34 D). Based on this effect, 37 eyes had a different axial classification of anterior corneal astigmatism and refractive astigmatism. In contrast, one eye (0.4%) had oblique ocular residual astigmatism and the ocular residual astigmatism superimposed with-the-rule anterior corneal astigmatism.

CONCLUSIONS

The magnitude of ocular residual astigmatism was relatively large in myopic children and predominantly compensated for anterior corneal astigmatism. Ocular residual astigmatism should be assessed in patients before fitting them with orthokeratology lenses.

Peripheral Refraction With Toric Orthokeratology and Soft Toric Multifocal Contact Lenses in Myopic Astigmatic Eyes

Purpose

There has been little research on myopia management options for patients with astigmatism. This study quantified changes in peripheral refraction induced by toric orthokeratology (TOK) and soft toric multifocal (STM) contact lenses.

Methods

Thirty adults with refractive error of plano to -5.00 D (sphere) and -1.25 to -3.50 D (cylinder) were enrolled. Cycloplegic autorefraction was measured centrally, ±20 degrees, and ±30 degrees from the line of sight nasally (N) and temporally (T) on the retina. Measurements were made at baseline, after 10 ± 2 days of TOK wear (without lenses on eye), and after 10 ± 2 days of STM wear (with lenses on the eyes) and compared with repeated-measures analysis of variance.

Results

Compared to baseline, TOK induced a myopic shift in defocus (M) at all locations (all P < 0.01), but STM only induced a myopic shift at 20 T in both eyes and 30 N/T in the left eye (all P < 0.01). TOK resulted in more myopic defocus than STM at all locations (all P < 0.05) except 20 T in the left eye. TOK induced more J0 astigmatism at all locations (all P < 0.02), except 20 N in the right eye; J0 with STM was different than baseline at 20 N in both eyes and 30 N in the right eye (all P < 0.02). TOK induced more J0 astigmatism than STM at all locations (all P < 0.01), except 20 T in the left eye. Differences in J45 astigmatism, when significant, were clinically small.

Conclusions

Greater amounts of peripheral myopic defocus and J0 astigmatism were induced by TOK compared to STM, which may influence efficacy for myopia management.

Preliminary Evaluation of a Smartphone App for Refractive Error Measurement

Purpose

The purpose of this study was to evaluate the potential feasibility of using a smartphone app in myopia screening.

Methods

The app estimates myopic refractive error by measuring the far point distance for reading three 20/20 Tumbling E letters. In total, 113 myopic subjects with astigmatism no greater than -1.75 diopters (D) were enrolled from 5 sites. The mean age was 22 ± 8.5 years. The app measurement was compared with noncycloplegic subjective refraction measurement or autorefractor if subjective refraction was not available. In addition, 22 subjects were tested with the app for repeatability.

Results

For 201 eyes included, the range of spherical equivalent refraction error was 0 to -10.2 D. The app measurement and clinical measurement was highly correlated (Pearson R = 0.91, P < 0.001). There was a small bias (0.17 D) in the app measurement overall, and it was significantly different across the 5 sites due to different age of subjects enrolled at those sites (P = 0.001) - young adults in their 20s were underestimated the most by 0.49 D, whereas children were overestimated by 0.29 D. The mean absolute deviation of the app measurement was 0.65 D. The repeatability of multiple testing in terms of 95% limit of agreement was ±0.61 D.

Conclusions

Overall, the app measurement is consistent with clinical measurement performed by vision care professionals. The repeatability is comparable with that of some autorefractors. Age-associated human factors may influence the app measurement.

Translational Relevance

The app could be potentially used as a mass screening tool for myopia.

Higher-order aberrations and their association with axial elongation in highly myopic children and adolescents

BACKGROUND

Vision-dependent mechanisms play a role in myopia progression in childhood. Thus, we investigated the distribution of ocular and corneal higher-order aberrations (HOAs) in highly myopic Chinese children and adolescents and the relationship between HOA components and 1-year axial eye growth.

METHODS

Baseline cycloplegic ocular and corneal HOAs, axial length (AL), spherical equivalent (SE), astigmatism and interpupillary distance (IPD) were determined for the right eyes of 458 highly myopic (SE ≤-5.0D) subjects. HOAs were compared among baseline age groups (≤12 years, 13-15 years and 16-18 years). Ninety-nine subjects completed the 1-year follow-up. Linear mixed model analyses were applied to determine the association between HOA components, other known confounding variables (age, gender, SE, astigmatism and IPD) and axial growth. A comparison with data from an early study of moderate myopia were conducted.

RESULTS

Almost all ocular HOAs and few corneal HOAs exhibited significant differences between different age groups (all p<0.05). After 1 year, only ocular HOA components was significantly negative associated with a longer AL, including secondary horizontal comatic aberration (p=0.019), primary spherical aberration (p<0.001) and spherical HOA (p=0.026). Comparing with the moderate myopia data, the association of comatic aberration with AL growth was only found in high myopia.

CONCLUSION

In highly myopic children and adolescents, lower levels of annual ocular secondary horizontal comatic aberration changes, besides spherical aberrations, were associated with axial elongation. This suggests that ocular HOA plays a potential role in refractive development in high myopia.

The profile of astigmatism in 6-12-year-old children in Iran

PURPOSE

To determine the prevalence of astigmatism and its determinants in schoolchildren aged 6-12 years.

METHODS

The students selected by stratified cluster random sampling in Shahroud, north of Iran. Optometric examination included uncorrected visual acuity, refraction with autorefractometer, manifest refraction with retinoscopy followed by subjective and cycloplegic refraction (after two drops of cyclopentolate 1% with 5min interval were instilled in each eye). A cylinder power ≥0.75diopter (D) in at least one eye was considered as astigmatism. The prevalence of astigmatism was reported based on a cylinder power higher than 0.50, 1.00, and 2.00D in cycloplegic refraction, followed by power vector analysis.

RESULTS

After applying the inclusion criteria, the data of 5528 children were analyzed. The prevalence of astigmatism was 16.7% (95% CI: 15.6-17.7) in total, 16.6% (95% CI: 15.2-18.0) in boys and 16.8% (95% CI: 15.2-18.3) in girls (p=0.920) and decreased from 21.5% in 6-year-old children to 13.7% in 10-year-olds, and then again increased to 18.3% in children aged 12 years. Moreover, 17.2% (95% CI: 16.0-18.3) of urban and 12.1% (95% CI: 10.0-14.1) of rural children had astigmatism (p<0.001). The prevalence of with-the-rule, against-the-rule, and oblique astigmatism was 14.2%, 2.1%, and 0.33%, respectively. The mean cylinder power was -1.31, -0.46, and -0.44D in children with spherical myopia, emmetropia, and hyperopia, respectively (p<0.001). Urban students had a higher J0 and boys had a higher J45.

CONCLUSION

The prevalence of astigmatism in this study was lower than previous studies. Astigmatism prevalence was markedly higher in urban children.

Serum levels of cytokines in infants treated with conbercept for retinopathy of prematurity

Intravitreal anti-vascular endothelial growth factor (VEGF) agents have revolutionized the treatment of retinopathy of prematurity (ROP); however, there are concerns regarding the potential systemic complications caused by those treatments. This study aimed to determine the serum concentrations of cytokines in infants with ROP and to evaluate the changes in serum VEGF concentrations after intravitreal conbercept (IVC). Sixty infants with ROP treated with IVC 0.25 mg were included. Blood samples were collected before treatment as well as 1 week and 4 weeks after treatment. Serum levels of 45 types of cytokines were measured by a multiplex bead assay. We observed that IVC 0.25 mg in ROP patients suppressed the circulating levels of VEGF-A and VEGF-D as of 1 week after injection, and these growth factor levels returned to baseline at 4 weeks. No significant differences were observed in the serum levels of the other cytokines between baseline and 1 or 4 weeks after IVC.

Astigmatism in school students of eastern China: prevalence, type, severity and associated risk factors

BACKGROUND

China has been undergoing dramatic economic development, accompanied by increased education load on the young children. This study is to investigate the prevalence, type, severity, and associated risk factors of astigmatism in school students in eastern China.

METHOD

In this cross-sectional school-based study, students underwent refraction using NIDEK non-cycloplegic autorefractor. Astigmatism was defined as cylinder 1.5 diopter (D) or greater, and high astigmatism was defined as cylinder 3.0 D or greaterMultivariate regression models were used to determine factors associated with astigmatism.

RESULTS

Among 4801 children (55% male) with mean age (±standard deviation) 12.3 (±3.8) years, 680 (14.2, 95% confidence interval (95% CI): 13.2-15.2%) had astigmatism (85% were with-the-rule) and 103 (2.2, 95% CI: 1.8-2.6%) had high astigmatism. The prevalence rate of astigmatism was 7-8% in grades 4 or below, 15-16% in grades 6-8, 20% in grade 9, and 20-25% in grade 10 or above. In multivariate analyses, higher grade and male gender were associated with higher prevalence of astigmatism (all p < 0.0001) and high astigmatism (p = 0.04 for grade, p = 0.001 for gender). When multivariate models were further adjusted by spherical equivalent, only gender remained statistically associated with astigmatism (odds ratio (OR) = 1.65, p < 0.0001) and high astigmatism (OR = 2.21, p = 0.0004), myopic and hyperopic refractive error were significantly associated with higher risk of astigmatism and high astigmatism (all p < 0.0001).

CONCLUSION

Astigmatism is common in Chinese school-age children and increases with grade. Majority of astigmatism is with-the-rule. Male gender and myopic or hyperopic refractive error are significantly associated with higher prevalence and severity of astigmatism.

Corneal topography, anterior segment and high-order aberration assessments in children with ≥ 2 diopter astigmatism

PURPOSE

To assess topographic findings, anterior segment parameters and high-order aberrations (HOAs) by using corneal tomography in children with 2 diopters (dp) or more astigmatism.

METHODS

Children with 2 dp or more astigmatism (study group) and children with astigmatism less than 1 dp (control group) were recruited. Corneal astigmatism, mean, steep, flat keratometry (K) findings, anterior and posterior K results and anterior segment parameters including anterior chamber depth, kappa distance, horizontal corneal diameter, mean, central, middle, peripheral corneal thicknesses (CT), white-to-white (WTW) distance and pupil diameter were measured by Galilei G4 Dual Scheimpflug corneal tomography. HOAs were also assessed and compared between groups.

RESULTS

Fifty-eight eyes of 37 children in the study group and 37 eyes of 37 children in the control group were enrolled. The mean ages of groups were 9.7 ± 2.4 years and 9.3 ± 1.6 years in study and control groups, respectively. The mean astigmatism was 3.3 ± 1.1 dp and 0.5 ± 0.3 dp in study and control groups, respectively (p < 0.05). Total corneal astigmatism was 3.3 ± 0.84 dp and 1.14 ± 0.47 dp in study and control groups, respectively (p < 0.05). There was a significant difference between groups in terms of posterior steep K and posterior astigmatism values. Among anterior segment parameters, mean CT and WTW values were statistically different between groups. HOAs were found to be statistically different between groups.

CONCLUSION

Higher posterior corneal astigmatism, thinner mean CT and lower WTW distance were found in children with 2 dp or more astigmatism. Besides, HOAs were much more in these astigmatic children.