Changes of hyperopia reserve and other eye parameters among Chinese children aged 3-6 years old

doi:10.21203/rs.3.rs-2201477/v1

Purpose

Track refractive changes in preschool children to explore the characteristics of refractive changes, further delineate refractive status and provide data for the prevention of refractive errors in preschool children.

Methods

The refractive data of 26,528 preschoolers in 2021 and 16383 ones lasting for 2 years(2020 and 2021) aged 3–6 years were collected from different kindergartens in Suzhou High-tech Zone for the study(Until 23 July 2021). The refractive data of every participant was measured with the Welch Allyn Spot on non-cycloplegic refraction. A follow-up for all the included participants was performed. The spherical equivalent change was calculated, subsequently, the characteristics related to the change were performed.

Results

The chi-square test of 26528 preschoolers in 2021 showed a higher prevalence of hyperopia in boys (χ2 = 4.299, P = 0.038), and a higher prevalence of hyperopia reserve deficiency in boys (χ2 = 11.987, P = 0.001). And there are the trends for myopia (χ2 = 26.398, P < 0.001), astigmatism (χ2 = 58.838, P < 0.001), hyperopia reserve deficiency (χ2 = 24.290, P < 0.001) to increase with age. Trackable data shows the incidence of refractive errors (= Number of new patients in 2021/number of non-patients in 2020). After Chi-square that the incidence of hyperopia, astigmatism and myopia was statistically different at different ages and the incidence of the three at 5 years-old are at the high level. The further analysis of the newly developed people with hyperopia reserve deficiency shows the decline rate of hyperopia reserve has slowed down with age, the rate of decline of 2–3 and 3–4 are faster than 4-5and 5–6 significantly.

Conclusion

In preschool, boys possess higher hyperopia than girls; and, as age increases, but the increase rate of hyperopia reserve deficiency for girls is faster with the growth of age. There were the special incidence of hyperopia and astigmatism at 5 years old. And we should watch out for sharp changes in early hyperopia reserve. At the same time, the serious lack of hyperopia reserve(19%) of children in Suzhou also sounded an alarm for myopia prevention.

preschoolers

hyperopia reserve dificiency

myopia

refractive error

incidence

Unlike youngers or adults, the refractive state of the newborn is hyperopia. Emmetropization the transition from hyperopia to emmetropia appears with age[1].It is a gradual process so we need a criteria to evaluate it. Most literature improves the standard of children’s myopia to balance the situation. Therefore, there is a phenomenon that a few false-positive results make parents nervous in excess. So in this paper, we use “Hyperopia reserve deficiency” to replace it. The concept of “hyperopia reserve” is still being promoted. Although the literature on it is sparse, it has begun to be officially used in Chinese policy. 2022 Expert Consensus of Chinese Society of Preventive Medicine consider that China has been lacking a summary of the changes in the developmental parameters of the child's eye during the process of emmetropization, including changes in the hyperopia reserve[2] .Myopia, hyperopia, astigmatism and refractive aberrations without treatment in early childhood can develop into amblyopia. The prevalence of amblyopia is between 1–4%[3].And myopia increases the risk of retinal detachment, cataract, glaucoma, staphyloma, myopic macular degeneration, and myopic choroidal neovascularization[4].Asian children have higher rates of myopia than white children[5].Therefore, this paper investigates the refractive status of children aged 3–6 years in Suzhou, China, to support public health prevention.

Study Population

Suzhou Province is located in the South Jiangsu Province as a representative city in southern China. A saying goes, Heaven above, Suzhou and Hangzhou below. A total of 26,528 preschoolers aged 3–6 years(Until 23 July 2021) from different kindergartens in Suzhou High-tech Zone were selected. There were 12,957 boys and 12,571 girls, including 890 3-year-olds, 9,749 4-year-olds, 8,313 5-year-olds and 7,576 6-year-olds. The study was conducted once in July 2020 and once in July 2021, undergoing refractive testing with the Welch Allyn Spot with non-cycloplegia. The inclusion criteria were as follows: (1) No serious systemic organic diseases (e.g congenital circulatory and respiratory diseases) and informed parental consent of the subject. (2) Exclude subjects with serious eye disease or a history of past eye surgery, refusal of parents or the child being tested to cooperate or incomplete basic information or test results on the subject. The study was approved by the Ethics Committee of Soochow University Medical Department and informed consent was obtained from the guardians of all investigated subjects.

Examination and Definition

The refractive status of the children in this study was measured using the Welch Allyn Spot. All tests were performed in semi-dark room conditions without cycloplegia, and information on binocular spherical, columnar and axial lenses. We use the concept of hyperopia reserve for classification based on the “Notice of the General Office of the National Health and Wellness Commission on the issuance of the Standard for Eye Care and Vision Screening Services for Children Aged 0 to 6 (for trial implementation)”.(http://www.gov.cn/zhengce/zhengceku/2021-06/24/content_5620637.htm). (1)3、4 years old, astigmatism was defined as cylinder > 2.00 D, hyperopia was defined as sphere > 4.00 D, myopia was defined as sphere < − 3.00 D, anisometropia was defined as spherical aberration > 1.50D or cylindrical aberration > 1.00D.(2)5、6 years old, astigmatism was defined as cylinder > 1.50 D, hyperopia was defined as sphere > 3.50 D, myopia was defined as sphere < − 1.50 D. anisometropia was defined as spherical or cylindrical aberration > 1.00D.(3)Hyperopia reserve deficiency was defined as SE < + 0.00D.Either eye below this standard will be diagnosed.

Statistical Method

Statistical analysis was performed using the IBM SPSS 23. 0. Refractive data for preschoolers 2021 were determined by Pearson chi-square test. About rackable data from 2020 to 2021, the one-way ANOVA test was used for data satisfying the Gaussian distribution with homogeneity of variance, while the Welch test for data not satisfying the Gaussian distribution and Games-Howell correction for comparison each of two groups. All P values were two-sided with test level α = 0.05 and P < 0.05 considered statistically significant.

Distribution of refractive types by age and sex

The 26,528 children were classified according to gender, including 13,957 boys and 12,571 girls. And the chi-square test showed a higher prevalence of hyperopia in boys (1.3%) than in girls (1.0%) (χ2 = 4.299, P = 0.038). The higher prevalence of hyperopia reserve deficiency in boys (19.8%) is higher than girls (18.2%) (χ2 = 11.987, P = 0.001). The 26,528 children were classified according to age, including 890 3-years-old, 9,749 4-years-old, 8,313 5-years-old and 7,576 6-years-old, and the chi-square test showed a trend for myopia to increase with age (χ2 = 26.398, P < 0.001). Also astigmatism increases with age (χ2 = 58.838, P < 0.001), and a trend towards an increase in hyperopia reserve deficiency with age (χ2 = 24.290, P < 0.001). Subgroup analysis, adjusted for gender, showed that among boys, there was a tendency for myopia (χ2 = 12.369, P = 0.006), astigmatism (χ2 = 50.528, P < 0.001) and hyperopia reserve deficiency (χ2 = 8.086, P = 0.044) to increase with age. Among girls, myopia (χ2 = 14.537, P = 0.002), astigmatism (χ2 = 13.647, P = 0.003), and hyperopia reserve deficiency (χ2 = 21.351, P < 0.001) are still increasing with age. And according to the results of Table 1, drawing the Figs. 1of hyperopia and hyperopia reserve deficiency at different ages with gender, from which we can observe that the prevalence rate of hyperopia in boys increases faster with age, while the hyperopia reserve deficiency is girls.

Table 1. Comparison of the prevalence of refractive status at different ages by gender

Analysis of trackable data

The same 26,528 young children who had two refractive tests in 2020 and 2021 are subjected to calculate the incidence of refractive errors (= Number of new patients in 2021/number of non-patients in 2020). Chi square results showed that the incidence of hyperopia, astigmatism and myopia was statistically different at different ages. As the Table 2 shows that the incidence of the three at 5 years-old are at the high level. And the further analysis of the newly developed people with hyperopia reserve deficiency(Table 3) shows the decline rate of hyperopia reserve has slowed down with age. the rate of decline of 2–3 and 3–4 are faster than 4-5and 5–6 significantly.

Table 2

Comparison of the incidence of refractive status by age
	hyperopia reserve deficiency No,n(%)	hyperopia No,n(%)	astigmatism No,n(%)	anisometropia No,n(%)	myopia No,n(%)
3	119(16.7)	9(1.0)	24(2.8)	14(1.6)	1(0.1)
4	1199(15.1)	51(0.5)	193(2.1)	144(1.5)	2(0.0)
5	1016(15.0)	72(0.9)	273(3.5)	108(1.3)	21(0.3)
6	969(16.0)	46(0.6)	155(2.2)	107(1.5)	16(0.2)
total	3303(15.4)	178(0.7)	645(2.6)	373(1.5)	40(0.2)
χ2	3.860	9.880	36.656	1.249	18.649
P	0.277	0.020	< 0.001	0.741	< 0.001

Table 3

Comparison of SE decrease in left and right eyes of 2021 newly patients with hyperopia reserve deficiency by age group
Age change (2020–2021)	SE D-value of right eye	SE D-value of left eye
2–3	-0.527 ± 0.925	-0.622 ± 0.601
3–4	-0.458 ± 0.461	-0.567 ± 0.486
4–5	-0.403 ± 0.507	-0.507 ± 0.797
5–6	-0.420 ± 0.442	-0.509 ± 0.429
total	-0.432 ± 0.495	-0.534 ± 0.591
welchF	3.057	4.167
P	0.028	0.006

Hyperopia in boys and myopia progression in girls deserve attention

Like the results shown in Table 1 and Fig. 1, The hyperopia rate and progress speed of boys are higher than that of girls. Also a systematic study of children's refractive conditions in India shows that boys have a higher prevalence of hyperopia than girls[6]. Boys are more likely than girls to have hyperopia reserve deficiency in the text, but the paper[6] above shows that myopia prevalence is higher in females than in males in adolescence, and that myopia develops more rapidly in girls than in boys with age[7].This just fits the curve in Fig. 1 that the increase rate of hyperopia reserve deficiency for girls is faster with the growth of age. Some studies show that the rapid development of myopia in girls arrives between the ages of 7 and 9 years[8, 9]. Ensuring adequate hyperopia reserve in preschool can help to mitigate the negative outcomes of the rapid development of myopia in girls.

Development characteristics of astigmatism and hyperopia

Table 1 reflect the increasing detection rates of astigmatism, myopia and hyperopia reserve deficiency with age, after removing the influence of gender. At the same time, Table 2 shows that the incidence of hyperopia, astigmatism and myopia has a significant increase at 5 years old (the incidence may lack a certain degree of continuity due to the small sample size at 3 years old). This shows that astigmatism in preschool children increases with age, while it remains a major problem in the refractive status of young children [10] ,especially at 5 years old. The incidence of hyperopia also has a significant jump at 5 years old. At the same time, Kulp MT’s research shows that there is a positive correlation between hyperopia and astigmatism in preschool children[11]. Obviously, the difference between the definition of ametropia of 4 and 5 years-old has eliminated the natural physiological changes to some extent, but it is still higher than 6-years-old. It may be affected by some environmental changes during the vision change period of 4–5 years old for the increase of astigmatism and hyperopia, such as the increase of exposure time of electronic screen caused by the Covid-19. Or the remaining changes really prove that the incidence of ametropia of 5-years-old will have a significant jump or it should be further declined to define ametropia at 5 years old, especially hyperopia and astigmatism, which requires more research.

Watch out for sharp changes in early hyperopia reserve

The above results also show that the rate of myopia and hyperopia reserve deficiency changes with age. In order to further investigate the change of hyperopia reserve in different age groups, Table 3 analyzes the new hyperopia reserve deficient population, and finds that the SE changes at a higher rate at 2–3 and 3–4 years old than 4–5 and 5–6. So we should beware of the sharp decline of the early hyperopia reserve. With the shortage of hyperopia reserves, the myopia rate will continue to rise, and it will rise significantly after 6-years-old[12]. Enhance community intervention and improve the referral rate for initial screening abnormalities in children, thereby enhancing the prevention of myopia in preschool children[13].This paper explores the dynamic changes of preschool children's refraction, which provides support for the formulation of relevant standards, such as hyperopia reserve deficiency, especially the current situation that the supporting data for preschool children's standards are still vacant[2] .

Preschoolers have a serious problem of hyperopia reserve deficiency, accounting for about 20% of the population, meaning that they will face the challenge of myopia in the following school years.SE of children in this article,3-years-old(0.472 ± 0.809) D,4-years-old (0.468 ± 0.654 ) D,5-years-old (0.46 ± 0.671) D,6-years-old (0.407 ± 0.681) D are all lower than the standard in related research ,3-years-old(+ 1.49 ± 0.64)D[14],4-years-old (+ 1.21 ± 1.03)D,5-years-old(+ 1.24 ± 1.09)D,6-years-old(+ 1.07 ± 1.10)D[15].This gap of hyperopia reserve can not be ignored, although the data used in this paper with non-cycloplegia data will make the data higher slightly[16].Suzhou, China is an economically developed area, and there is a correlation between economy and vision, especially myopia[17].Therefore, we should pay more attention to the development of children's farsightedness reserves in such areas. About the deficiencies, this paper uses non-cycloplegia data, but the tracking sample size is large, and it is queue data, so the results still have strong reference value. There are only 890 people in the 3-year-old group, which is less than other groups. However, attention has been paid to this during the discussion, so the conclusion is still reliable.

In conclusion, this study showed the prevalence and incidence of different refractive error and the change of hyperopia reserve among preschool children in Suzou City. Among preschoolers, different genders and different ages have different refractive characteristics. In particular, we should pay attention to the high prevalence of hyperopia in boys, the rapid progress of myopia in girls and the faster decline of hyperopia reserve with the lower the age. We should focus more on prevention according to the characteristics of different refractive problems of preschool children, so as to improve the effect of prevention.

Acknowledgements

The authors thank preschool children, parents, and guardians who took part in the study. The authors also thank schools and the entire team of the Maternal and Child Health and Family Planning Service Center for their cooperation.

Author Contributions

XY,GHQ and ZH designed the experiment. PH, QDJ and LJ performed the experiment. WY and ZGW wrote the paper. All authors contributed to the article and approved the submitted version. All authors read and approved the final manuscript.

Availability of data and materials

The datasets generated and/or analysed during the current study are not publicly available due parental requirements but are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

The studies involving human participants were reviewed and approved by Jiangsu Provincial Health Commission's Ethics Committee and was in accordance with the

Helsinki Declaration. Informed consent was obtained from all participants.

If participants were under 16, the informed consent was obtained from a

parent and/or legal guardian. Eye examination were conducted after explaining the study to schools, parents or guardians, and children and obtaining their informed consent.

Consent for publication

Not applicable.

Funding

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Author details

¹School of Public Health, Soochow University, No. 199, Ren'ai Road, Suzhou Industrial Park ,Suzhou215123,China

²Suzhou High tech Zone Maternal and Child Health and Family Planning Service Center, No. 50, Kepu Road, Suzhou 215163,China

Yu Wang1,Hongqin Gao2,Guangwei Zhu1， Hong Pan2 ,Dengjuan Qian2，Juan Li2 ,Hong Zhu1* ,Yong Xu1

Burton MJ, Ramke J, Marques AP, Bourne RRA, Congdon N, Jones I, Ah Tong BAM, Arunga S, Bachani D, Bascaran C et al: The Lancet Global Health Commission on Global Eye Health: vision beyond 2020. The Lancet Global Health 2021, 9(4):e489-e551.
[Chinese expert consensus on the reference interval of ocular hyperopia reserve, axial length, corneal curvature and genetic factors in school-age children (2022)]. [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 2022, 58(2):96-102.
Rogers GL, Jordan CO: Pediatric vision screening. Pediatrics in review 2013, 34(3):126-133.
Tideman JW, Snabel MC, Tedja MS, van Rijn GA, Wong KT, Kuijpers RW, Vingerling JR, Hofman A, Buitendijk GH, Keunen JE et al: Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol 2016, 134(12):1355-1363.
Theophanous C, Modjtahedi BS, Batech M, Marlin DS, Luong TQ, Fong DS: Myopia prevalence and risk factors in children. Clin Ophthalmol 2018, 12:1581-1587.
Sheeladevi S, Seelam B, Nukella PB, Modi A, Ali R, Keay L: Prevalence of refractive errors in children in India: a systematic review. Clin Exp Optom 2018, 101(4):495-503.
Hu Y, Ding X, Long W, He M, Yang X: Longitudinal Changes in Spherical Equivalent Refractive Error Among Children With Preschool Myopia. Investigative Ophthalmology & Visual Science 2019, 60(1):154-160.
Tricard D, Marillet S, Ingrand P, Bullimore MA, Bourne RRA, Leveziel N: Progression of myopia in children and teenagers: a nationwide longitudinal study. British Journal of Ophthalmology 2021:bjophthalmol-2020-318256.
Hyman L, Gwiazda J, Hussein M, Norton TT, Wang Y, Marsh-Tootle W, Everett D, Group CS: Relationship of Age, Sex, and Ethnicity With Myopia Progression and Axial Elongation in the Correction of Myopia Evaluation Trial. Archives of Ophthalmology 2005, 123(7):977-987.
Huang J, Maguire MG, Ciner E, Kulp MT, Cyert LA, Quinn GE, Orel-Bixler D, Moore B, Ying G-S, Group ftViPS: Risk Factors for Astigmatism in the Vision in Preschoolers Study. Optometry and Vision Science 2014, 91(5):514-521.
Kulp MT, Ying GS, Huang J, Maguire M, Quinn G, Ciner EB, Cyert LA, Orel-Bixler DA, Moore BD: Associations between hyperopia and other vision and refractive error characteristics. Optom Vis Sci 2014, 91(4):383-389.
Ma Y, Qu X, Zhu X, Xu X, Zhu J, Sankaridurg P, Lin S, Lu L, Zhao R, Wang L et al: Age-Specific Prevalence of Visual Impairment and Refractive Error in Children Aged 3-10 Years in Shanghai, China. Invest Ophthalmol Vis Sci 2016, 57(14):6188-6196.
French AN, Murphy E, Martin F, de Mello N, Rose KA: Vision Screening in Children: The New South Wales Statewide Eyesight Preschooler Screening Program. Asia-Pacific journal of ophthalmology (Philadelphia, Pa) 2022, 11(5):425-433.
Guo X, Fu M, Ding X, Morgan IG, Zeng Y, He M: Significant Axial Elongation with Minimal Change in Refraction in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study. Ophthalmology 2017, 124(12):1826-1838.
Zhang L, He X, Qu X, You X, Wang B, Shi H, Tan H, Zou H, Zhu J: Refraction and Ocular Biometry of Preschool Children in Shanghai, China. Journal of ophthalmology 2018, 2018:5205946.
Wilson S, Ctori I, Shah R, Suttle C, Conway ML: Systematic review and meta-analysis on the agreement of non-cycloplegic and cycloplegic refraction in children. Ophthalmic Physiol Opt 2022, 42(6):1276-1288.
Wang H, Li Y, Qiu K, Zhang R, Lu X, Luo L, Lin JW, Lu Y, Zhang D, Guo P et al: Prevalence of myopia and uncorrected myopia among 721 032 schoolchildren in a city-wide vision screening in southern China: the Shantou Myopia Study. Br J Ophthalmol 2022.

No competing interests reported.

Changes of hyperopia reserve and other eye parameters among Chinese children aged 3-6 years old

Status:

Version 1

Abstract

Purpose

Methods

Results

Conclusion

Figures

Introduction

Materials And Methods

Study Population

Examination and Definition

Statistical Method

Result

Distribution of refractive types by age and sex

Analysis of trackable data

Discussion

Hyperopia in boys and myopia progression in girls deserve attention

Development characteristics of astigmatism and hyperopia

Watch out for sharp changes in early hyperopia reserve

Conclusion

Declarations

Acknowledgements

Ethics approval and consent to participate

Consent for publication

Funding

Competing interests

Author details

References

Additional Declarations

Status:

Version 1