Prevalence of and factors associated with astigmatism in preschool children in Wuxi City, China

Characteristics of astigmatism in school-age children aged 5 to 13 years in northeast Sichuan: a cross-sectional school-based study

Background

Astigmatism is closely associated with myopia progression, vision loss, eye fatigue and amblyopia, which seriously endangers children's eye health. This study aims to investigate the prevalence and characteristic distribution of astigmatism in children in Langzhong City, providing valuable insights for allocating resources and develop prevention and control strategies.

Methods

A cross-sectional study and random sampling survey were conducted. Between January and November 2021, 21,415 students aged 5 to 13 years from 14 primary schools in Langzhong City underwent non-cycloplegic refractive testing using autorefraction. The data on myopia were analyzed using SPSS (Statistical Package for the Social Sciences) version 23.0.

Results

The inclusion criterion was set at an absolute astigmatism value of ≥0.50D. Among the 21,415 children studied, 61.70% were found to have astigmatism. The prevalence of astigmatism varied significantly across different grades (χ2=501.414, P<0.001). The predominant types of astigmatism were mild astigmatism (0.50-1.00D) and with-the-rule astigmatism. Mixed astigmatism was primarily observed in children in grades 1 and 2, while compound myopic astigmatism was more common in children in grades 3 to 6. These differences were statistically significant. As the degree of astigmatism increased, the proportions of against-the-rule astigmatism, oblique astigmatism, compound myopic astigmatism, and simple hyperopic astigmatism decreased, whereas the proportions of with-the-rule astigmatism, mixed astigmatism, and compound hyperopic astigmatism increased.

Conclusions

The prevalence of astigmatism among school-age children aged 5 to 13 years in northeast Sichuan is notably high, with compound myopic astigmatism and with-the-rule astigmatism being the most common types. Regular refractive examinations are crucial for the early detection and management of astigmatism.

Retinopathy of prematurity screening: prevalence and risk factors of ophthalmic complications in non-treated preterm infants

INTRODUCTION

Retinopathy of prematurity (ROP) is a vision-threatening disease of premature infants. Practice guidelines recommend that all infants screened for ROP receive follow-up eye examinations to screen for ophthalmic complications.1 The purpose of this study was to identify risk factors for the development of strabismus, amblyopia, high refractive error, and cataracts among ROP-screened, non-treated infants.

METHODS

Retrospective single-centre study of ROP-screened, non-treated premature infants with ophthalmic follow-up. Clinical variables were screened for association with ocular findings at follow-up. Multivariable logistic regression was used to determine the risk factors associated with ocular findings.

RESULTS

309 patients were seen for follow-up at 0.97 (0.69) [mean (SD)] years after neonatal intensive care unit (NICU) discharge. Strabismus was predicted by occipitofrontal circumference (OFC) z-score at NICU discharge (OR 0.61; 95% CI [0.42, 0.88]; p = 0.008), intraventricular haemorrhage (IVH) grade III or IV (OR 3.18; 95% CI [1.18, 8.54]; p = 0.02), and exclusive formula feeding at NICU discharge (OR 2.20; 95% CI [1.07, 4.53]; p = 0.03). Significant predictors of amblyopia were OFC z-score at discharge (OR 0.55; 95% CI [0.31, 0.96]; p = 0.03) and necrotising enterocolitis (NEC) (OR 6.94; 95% CI [1.38, 35.00]; p = 0.02). NEC was a significant risk factor for high refractive error (OR 7.27; 95% CI [1.39, 37.94]; p = 0.02).

CONCLUSIONS

Among premature infants screened but not treated for ROP, severe IVH, NEC, low OFC z-score, and exclusive formula feeding at NICU discharge were risk factors for ocular morbidity. These findings affirm the value of ophthalmic follow-up for all ROP-screened infants, particularly those with the identified risk factors.

The response of retinal ganglion cells to optical defocused visual stimuli in mouse retinas

Myopia and astigmatism are two primary types of refractive errors characterized by inaccurate focusing images on the retina. This study aimed to investigate the response characteristics of Retinal Ganglion Cells (RGCs), represented by alpha (α) RGCs, when exposed to focused, simulated spherically defocused images and astigmatically defocused images projected onto mouse retinas. Negative pressure was applied to stretch the soma of RGC in vitro to simulate myopia using a 7-8 μm diameter glass microelectrode, resulting in a 5% increase in the cell's diameter. A custom-made device was utilized to project spherically (equal to ±10 and ± 20 D) and astigmatically (+6.00 D) defocused images onto the retinas. As a control for a deficient intact retinal circuit, αRGCs of connexin 36 knockout (Cx36 KO) mice were used. The response of αRGCs varied significantly in terms of spikes, excitatory postsynaptic currents (EPSCs) and capacitances under stretching conditions to mimic myopia. Significant differences in the amplitudes of EPSCs were observed in the majority of αRGCs when exposed to focused and spherically defocused images in normal and mechanically simulated myopic retinas. However, this difference was not observed in αRGCs of Cx36 KO mice. αRGCs demonstrated significant differences in response between focused and astigmatically defocused images. Once again, αRGCs of Cx36 KO mice did not display differences. αRGCs have the ability to detect focused, spherically, and astigmatically defocused images and exhibit differential responses ex vivo. Gap junction subunit Cx36 may play a crucial role in transmitting visual signals associated with developing and perceiving refractive errors.

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.