The prevalence of refractive error in schoolchildren.

CLINICAL RELEVANCE: Information on the refractive error prevalence in school-aged children will result in delivering the optimal eye health service to this group. BACKGROUND: Understanding the prevalence of refractive error in school-aged children is crucial to reduce the consequences of uncorrected refractive error. This study aims to investigate the prevalence of refractive error among school-aged children in Shiraz, Iran. METHODS: In this cross-sectional population-based study, 2001 schoolchildren aged 6-12 years participated. All participants underwent cycloplegic refraction. Spherical equivalent (SE) of -0.50 dioptre or more was considered as myopia, SE of +2.00 dioptre or more as hyperopia, and astigmatism as cylinder power of 0.75 dioptre or more. The difference of 1.00 dioptre or more between two eyes defined as anisometropia. RESULTS: The prevalence of myopia was 11.6% (95% confidence interval [CI]: 10.2-13.1%), hyperopia 6.7% (95%CI: 5.6-7.9%), and astigmatism 28.9% (95%CI: 26.9-31.0%), out of which 82.1% had with the rule astigmatism. Anisometropia was detected in 4.0% (95%CI: 3.2-5.0%) of children. Astigmatism and anisometropia were significantly higher in boys (p < 0.001, p = 0.03 respectively). The SE decreased significantly with increasing age (p < 0.001) indicating an increase in myopia with age. In addition, the rate of myopic astigmatism increased with age (p < 0.001). Among studied schoolchildren 97.0% could achieve the best-corrected visual acuity of 6/6 and 3.0% could not in the better eye. CONCLUSION: Astigmatism was the most common refractive error among primary school children. The prevalence of myopia was relatively higher than other studies conducted in Iran, and it increased with age. These results may highlight the role of lifestyle changes and increased near work activities on the myopic shift in school-aged children. The findings provide information for screening programmes in school-aged children.

The Prevalence and Causes of Low Vision and Visual Impairment in School-Aged Children: The Shiraz Pediatric Eye Study.

Purpose: To determine the prevalence and causes of visual impairment (VI) in Shiraz schoolchildren aged between 6 and 12 years. Methods: In the present population-based study, stratified random sampling was used to select 2400 schoolchildren aged 6-12 years from all four educational districts of Shiraz, Iran. Using the definitions of the World Health Organization, VI was defined as best-corrected visual acuity (BCVA) ≤0.5 logMAR (20/60) in the better eye, and blindness as BCVA worse than 1.3 logMAR (20/400) in the better eye. The low vision was defined as BCVA equal to or worse than 0.5 logMAR (20/60) in either eye. Data were recorded from a detailed interview and ocular examination of each eligible student. Results: The mean age of the students was 9.1 ± 1.6 years. The prevalence of VI was 3/2001 (0.14%). The cause of VI in all these three patients (100%) was amblyopia due to high refractive errors (high ametropia and astigmatism). Regarding the main refractive errors leading to VI among these three patients, one patient had bilateral high hyperopia (compound hyperopic astigmatism), one of them had bilateral high astigmatism, and the other one had compound myopic astigmatism. According to a visual acuity of less than or equal to 20/60 in at least one eye, 9/2001 (0.4%) of children had low vision. Conclusions: This study revealed a low prevalence of VI in a sample of 6- to 12-year-old school-aged children. Amblyopia in the setting of high ametropia and astigmatism were the most common causes of VI.

Distribution of intraocular pressure in healthy Iranian children: the Shiraz Pediatric Eye Study.

PURPOSE: To describe the mean and normal range of intraocular pressure (IOP) and its associations in healthy Iranian school children using the noncontact tonometer. METHODS: In this cross-sectional study as part of the Shiraz Pediatric Eye Study, a stratified random sampling was performed among elementary school children of Shiraz, Iran. Basic demographics and socioeconomic status of households, past medical history, drug history, and eye health history were collected for each eligible student. Children underwent complete ophthalmic examination. Axial length, corneal curvature, and anterior chamber depth were measured using the IOL-Master 500. RESULTS: Of 2,001 eligible children, 1,901 (95.0%; 3,802 eyes) with a mean age of 9.1 ± 1.6 years (standard deviation; range, 6-12 years) had reliable IOP. The mean spherical equivalent refraction was 0.5 ± 1.3 D for the right eye and 0.6 ± 1.2 D for the left eye. Mean IOP in the right eye was 15.1 ± 2.5 mm Hg (median, 15.0; range, 8.0-27.0 mm Hg); in the left eye, 15.2 ± 2.5 mm Hg (median, 15.0; range, 9.0-28.0 mm Hg). In multiple regression analyses, the mean IOP was significantly lower among asthmatic children compared to normal participants (P = 0.007). The measured IOP was significantly higher in myopic participants than hyperopic patients (P = 0.003). CONCLUSIONS: This study provides a useful normative IOP database using the noncontact tonometer for healthy Iranian school children.

The Shiraz Pediatric Eye Study; a Population Based Survey of School Age Children: Rationale, Design and Baseline Characteristics.

PURPOSE: To describe the rationale, study design, methodology, and baseline characteristics of the Shiraz Pediatric Eye Study, a population-based survey of schoolchildren in Shiraz, Iran. METHODS: This population-based study included schoolchildren aged 6-12 years from all four educational districts of Shiraz who were recruited in years 2015-2016. Stratified random sampling was used to select 2400 participants from all districts. Data were recorded from a detailed interview and ocular evaluation of each eligible student. The eye examination comprised uncorrected and best corrected visual acuity measurement, refraction, external eye examination (including specific strabismus and lid evaluation tests), slit lamp biomicroscopy, intraocular pressure measurement, the Ishihara color vision test, and stereoacuity. Exophthalmometry, optical biometry, and optical coherence tomography were performed for a randomly selected subset of children. General characteristics and socioeconomic variables were also recorded to assess risk factors. RESULTS: From a total of 2400 selected students, 2001 (83.3%) participated in the study. The mean age of the students was 9.1 ± 1.6 years, and 59.7% were girls. Most children had at least one parent with a diploma or less than diploma (63.5%), and 2.2% had illiterate parents. CONCLUSION: This study is expected to provide accurate estimates of the prevalence of visual impairments and their related determinants in Shiraz. In addition, it will identify children who should be targeted by blindness prevention programs.

Correlation Between Intraocular Pressure and Central Corneal Thickness in Persian Children.

INTRODUCTION: This study aimed to determine intraocular pressure (IOP) and central corneal thickness (CCT) measurements in healthy Persian children to find clinical reference values in this ethnicity. Additionally, we examined the possible relationship between these measurements. METHODS: This cross-sectional study included 262 eyes of 131 Persian primary school children between 6 and 13 years of age. All eyes were healthy and had no anterior or posterior segment abnormalities, corneal disease, or evidence of glaucoma. Specular microscopy was used to measure CCT and both noncontact tonometry (NCT) and Goldmann applanation tonometer (GAT) were used to measure IOP. Correlations between IOP measurements were also examined. RESULTS: Mean CCT was 513.47 ± 34.51 µm in the right eye (OD) and 513.93 ± 33.88 µm in the left eye (OS). The CCT was not significantly different between older (10-13 years) and younger (6-9 years) patients. Mean IOP measured with GAT was 13.86 ± 2.13 mmHg OD and 13.72 ± 2.04 mmHg OS and mean IOP measured with NCT was 15.26 ± 2.38 mmHg OD and 15.11 ± 2.18 mmHg OS. The IOP and CCT measured with GAT were weakly correlated (OD: r = 0.141, P = 0.114; OS: r = 0.236, P = 0.007). However, IOP and CCT measured with NCT (OD: r = 0.487, P = 0.000; OS: r = 0.456, P = 0.000) were moderately correlated. Our outcomes demonstrated that for 100 µm increase in CCT, IOP measured with GAT and NCT increased by 0.8 and 3.3 mmHg, respectively, in OD and by 1.4 and 2.9 mmHg in OS. Based on intraclass correlation coefficients, IOP measurements made with GAT and NCT were in fair agreement in OD and in good agreement in OS. CONCLUSION: The IOP and CCT in healthy Persian school children (6-13 years old) were positively correlated. Our findings revealed that corneal thickness is thinner in Persian children than in most other racial groups. FUNDING: This study has been funded by deputy dean in research of School of Medicine and deputy vice chancellor of Shiraz University of Medical Sciences, Shiraz, Iran.