Analysis on visual screening result of children aged 0-6 years old by using the SureSight automatic screening refractor in Binhu District, Wuxi City

Abstract

KEYWORDS:preschool children; vision screening; ametropia; astigmatism; anisometropia

INTRODUCTION

The development of the human eyeball is accompanied by the evolution of the refractive system. With the increase in age, the refractive state of children’s eyes tends to gradually shift from hyperopia to myopia.The World Health Organization estimates that 80% of visual impairment can be prevented or cured by treatment. Globally, uncorrected refractive errors are the main cause of moderate and severe visual impairment[1]. Friedmanetal[2]suggested that even if there is no obvious main complaint, no eye findings from a pediatrician, no significant family eye history, and no systemic risk factors, all 4-year-old children should receive a comprehensive eye examination by a pediatric ophthalmologist. If preschool children do not have a systematic and comprehensive eye examination, some diseases are easily overlooked, such as partial cataracts, small-angle strabismus, or unilateral vision loss. Some previous research results have proved that when pre-school vision screening is combined with corresponding treatment, the prevalence of amblyopia will be greatly reduced[3-6]. When examining children with ophthalmological or neurological problems, it is vital to know the normative data for a specific age and race. Refractive errors are the most common cause of children’s vision loss. Several papers in different regions have documented the increasing rate of myopia[7-9], and reports from Asia have also documented the development of early childhood myopia[10]. In recent studies, it has been found that the prevalence of amblyopia and hyperopia in preschool children is relatively high, but myopia is not found, which leads to the conclusion that myopia does not seem to be formed before the age of 10[11]. To understand the visual development of preschool children aged 0-6 years in Binhu District of Wuxi city. In this study, a total of 3 695 children were surveyed by census method from October 2019 to January 2020.

SUBJECTSANDMETHODS

EthicalApprovalThis research was reviewed by an independent ethical review board and conforms with the principles and applicable guidelines for the protection of human subjects in biomedical research. The survey followed the Helsinki Declaration and the Medical Ethics Committee of the Wuxi 9thAffiliated Hospital of Soochow University (No.LW2021028). All participants signed an informed written consent. And all participants did not receive a stipend.

ParticipantsA total of 3695 preschool children from Binhu District, Wuxi, China，were invited to participate in the vision screening project (n=3695). Finally, 3673 children completed the kindergarten screening and eye examination (n=3 673). These children are invited to participate in the study, regardless of whether they have eye diseases or not. The children were screened by an experienced optometrist in the kindergarten, and then a more detailed examination by another optometrist from the Wuxi 9thAffiliated Hospital of Soochow University. Preschool children aged 0-6 are invited to participate in the vision screening program. The study was conducted from October 2019 to January 2020.

ScreeningMethodProfessionally trained ophthalmologists have finished the complete eye examinations for preschool child including red-reflex, external, the visual behavior, the uncorrected visual acuity, and use the U.S. Weilun SureSight handheld vision screener to perform diopter examinations. It is required that in the semi-dark room, the child mode is selected without the cycloplegia of the child, the working distance measured is 35 cm, and the child’s eyeball is tested for diopter. Screener detection range: spherical lens is +6.00 D to -5.00 D, cylinder lens is +3.00 C to -3.00 C, when the detection range is exceeded, the screener displays ±9.99, no detection result. The number of scans of the screener ≥6 indicates good reliability. Binocular distance visual acuity was measured, uncorrected and recorded as decimal values for this study. Visual acuity is tested with the Standard Logarithmic Distance Visual Acuity E Chart (SLD-11-5m, Shang Hai), which is the most commonly used visual acuity charts in China, and the distance testing was performed at 5 m. Kay Pictures VA Chart (Kay Pictures Ltd, Tring, UK) was used, designed for children who cannot recognize the E chart. Children with abnormal screening results are notified to their parents to go to the ophthalmology department for further examination to confirm the diagnosis. Children whose screening results are in the suspicious range go to the ophthalmology clinic for follow-up review regularly.

CriteriaforScreeningResultsThe results are determined according to the latest norms of normal, suspicious, and abnormal eye refractive status screening for all age groups provided by Weilun Company. The specific standards are: S stands for spherical equivalent, C stands for cylindrical power[12]. The normal range of children aged 3-6 +0.75 D ≤S≤ +2.00 D, C≤ 1.00 D; Suspicious range +2.00 D

RESULTS

Among the 3695 preschool children, 3673 (99.40%) preschool children have completed the kindergarten screening and eye examination. After checking the data, 22 children were excluded as 17 with incomplete information and 5 beyond the age range of 0-6 years at the time of ocular examinations. The mean age of included participants was 4.85±0.93 years old and 53.25% were male (n=1 956), 46.75% were female (n=1 717). There is no statistical difference between men and women in each age group (χ2=7.200,P=0.066) (Table 1).

Table 1 Age and gender frequency distributions of the preschool children in the study n (%)

According the results of our screening, the mean visual acuity of the right eye of 0-3 years old children is 0.68±0.20, the left eye is 0.68±0.22, and the mean visual acuity of the right eye of 3-4 years old children is 0.73±0.23, the left eye is 0.73±0.23, and the mean visual acuity of the right eye of 4-5 years old children is 0.83±0.21, the left eye is 0.82±0.21, and the mean visual acuity of the right eye of 5-6 years old children is 0.91±0.21, the left eye is 0.90±0.21.

The prevalence of each refractive error in different age groups was shown in Table 2. According the result of visual acuity screening, 3116 preschool children were normal, 355 preschool children were diagnosed abnormal, 202 preschool children were diagnosed suspicious in different age groups by cyclopledic autorefraction. The screening results showed that the detection rate of abnormal and suspicious were on the rise with the increase of age, and the difference in the composition of the visual acuity screening results of children in all age groups was statistically significant (χ2=15.913,P=0.014). Among different age groups, there is a statistical difference between the abnormal group and the normal group (χ2=10.545,P=0.014), and there is no statistical difference between the other two groups (χ2=1.542,P=0.677;χ2=6.020,P=0.111).

The prevalence of each refractive error in different age groups was shown in Table 3. Although there were no differences in the prevalence of myopia and any refractive among different age groups (χ2=4.050,P=0.243;χ2=2.569,P=0.466), the prevalence of hyperopia, astigmatism, and anisometropia significantly increased with increasing age (χ2=79.055, 33.496, 9.029;P<0.01, <0.01, 0.028), and increased fastest in children from 4-6 years old.

The Table 4 shows the result that the prevalence of astigmatism about 3 673 preschool children (7 346 eyes) in different age groups. The preschool children in 0-3 years old were 6.94% (95%CI: 4.90%-9.00%) and the 3-4 years old were 8.98% (95%CI: 7.80%-10.20%), the 4-5 years old were 8.81% (95%CI: 7.70%-9.90%), the 5-6 years old were 5.75% (95%CI: 4.80%-6.70%). The prevalence of astigmatism in all preschool children was 7.83% (95%CI： 7.20%-8.40%). The prevalence of astigmatism in different age groups had no statistical difference (χ2=0.872,P=0.929).

DISCUSSION

Many medical institutions recommend that preschool children undergo vision screening to detect children’s vision problems and treat them at the same time[13-16]. Uncorrected severe refractive error is a common and serious problem[17-18], especially in preschool children. Although refractive error screening programs are carried out all over China, the results of refractive errors have not received enough attention. Often some parents think that low-grade refractive error is normal and harmless in preschool children, so the doctor’s advice is ignored. If it cannot be treated in time, it will have a serious impact on children’s daily life. This not only causes eyestrain, headaches and poor academic performance, but also leads to amblyopia[17-19]. Strabismus and severe refractive error are the main risk factors for amblyopia[20-22]. In many countries, the purpose of children’s vision screening programs is to detect and prevent serious vision problems that may affect education and daily life[23], and to detect and treat amblyopia before it becomes incurable[1]. This project is effective for detecting serious vision threats, such as strabismus or other rare factors affecting vision.

The present study investigates the prevalence of vision screening in Binhu District of Wuxi city. Meanwhile, from the results of our comprehensive vision screening, it was found that 8 children had strabismus, 8 children had ptosis, 2 children had trichiasis, and 1 child had abnormaled-reflex. A comprehensive vision screening can not only find preschool children’s vision problems, but also other eye diseases. The screening results of Table 3 showed that the detection rate of abnormal and suspicious were on the rise with the increase in age, and the preschool children have more and more vision abnormalities. According the results of Table 4, we found the prevalence of astigmatism has the highest proportion, followed by hyperopia and anisometropia. The results of this study indicate that the prevalence of astigmatism and hyperopia and anisometropia significantly increases in preschool children. However, the Table 5 showed the results that the prevalence of astigmatism about 3 673 preschool children (7 346 eyes) in different age groups. This result indicates that the prevalence of astigmatism is very high in preschool children, and it has seriously threatened the development of young children’s visual system. Furthermore, the visual impairment is becoming more and more serious in preschool children, thus warning parents, kindergarten teacher and ophthalmologists. In general, it was found from the results of vision screening that vision problems increased with age, similar to the results of previous reports[24-25].

Table 2 The result of visual acuity screening in different age groups n (%)

Table 3 The prevalence of significant refractive error in different age groups n (%)

Table 4 The prevalence of astigmatism in different age groups

Hyperopia: Spherical equivalent degree ≥3.5 D; Myopia: Spherical equivalent degree ≥1.0 D; Astigmatism: Cylinder degree ≥1.50 D with no significant spherical degree; Anisometropia was defined as ≥ 1.5 D interocular difference.

With the promotion of children’s vision prevention work, astigmatism, as an important disease in the process of vision development, that uncorrected astigmatism can cause bilateral vision loss due to bilateral meridian amblyopia, which has attracted the attention of parents and medical staff[26]. Astigmatism is caused by uneven surface curvature of the refractive body, deviation of the optical center from the line of sight, or abnormal refractive power of the refractive body. Preschool children are prone to have a large range of astigmatism. Astigmatism not only manifests as low vision, but also some patients have visual fatigue and visual distortion. Preschool children are in a sensitive period of visual development. Intensify the initial screening and establish a database of preschool children’s visual development. It is of great significance for the detection and prevention of astigmatism. Medical workers and parents should pay close attention to the visual development of children. Preschool children are in a sensitive period of visual development. The present result is aim to intensify the initial screening and establish a database of preschool children’s visual development. It is of great significance for the detection and prevention of visual impairment. Medical workers and parents should pay close attention to the visual development of children.

The research purpose of our project is to evaluate the importance of current vision screening and the possibility of combining it with other tests to be applied to the daily vision screening practice in our area. Once we find an abnormal or suspicious child, we need to recommend it to a special eye clinic for a further review. Early screening and early correction.

The revised WHO screening standards emphasize that a disease should be universal, treatment should be feasible and effective, screening should be cost-effective, and the overall benefit should outweigh the harm[27]. According to my country’s national conditions, paying attention to the vision problems of children and adolescents have become the main task of our country. Therefore, all our screening funds come from government funding.

In general, the strength of the current research lies in its large population size and detailed and accurate vision screening of all children. However, one limitation of this study is that it currently only includes kindergarten and preschool children, and they often have a good foundation of vision acuity[28]. At present, the research on vision screening for preschool children is mainly how to find the visual impairment or other children’s visual system diseases that need to be treated during the critical or sensitive period of children’s visual development. Our government has recently been involved in this project, attaching great importance to preschool children’s vision screening to find relevant eye diseases that are essential for treatment, and to ensure that children are fully prepared for learning when they enter kindergarten or first grade. Ophthalmologists have in the past and should continue to lead the way in developing, testing, and advocating the implementation of effective, evidence based, cost-effective screening programs.