Three optical intervention methods for low myopia control in children: a one-year follow-up study

doi:10.21203/rs.3.rs-4196516/v1

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Three optical intervention methods for low myopia control in children: a one-year follow-up study

https://doi.org/10.21203/rs.3.rs-4196516/v1

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published 31 Jul, 2024

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Objective This study aimed to compare the one-year efficacy of myopia prevention and control using three optical intervention methods - single vision lens (SVL), high aspherical lenticule (HAL), and orthokeratology (OK) lens - in children with low myopia.

Methods A cohort of 150 children aged 7-12 years with low myopia was recruited and divided into three groups: SVL (n = 50), HAL (n = 50), and OK group (n = 50), based on their preference for glasses. Follow-up assessments were carried out over one year, focusing on data from the right eye for statistical analysis. Baseline characteristics such as gender, age, axial length (AL), equivalent spherical refractive error (SER), flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), white-to-white corneal diameter (WTW), and non-contact tonometry (NCT) measurements were gathered and compared among the three groups before any intervention. Changes in AL growth after 1 year of intervention were assessed across the three groups. Subsequently, the AL growth control rates between the HAL and OK groups were compared, with the SVL group serving as the reference standard.

Results The study found no statistically significant variances in baseline characteristics (gender, age, SER, AL, K1, K2, WTW, and NCT) among the SVL, HAL, and OK groups (all p > 0.05). Following a one-year intervention, AL growth rates were as follows: HAL group (0.163 ± 0.1130mm) < OK group (0.280 ± 0.170mm) < SVL group (0.516 ± 0.190mm), with statistically significant disparities (p < 0.001). The HAL group demonstrated a higher 1-year AL growth control rate (68.41%) compared to the OK lens group (45.74%) for children aged 7-12 with low myopia, with a statistically significant distinction (p < 0.001).

Conclusion Compared to SVL, HAL and OK lens are more effective in controlling axial growth in mild myopia. Specifically, HAL shows superior outcomes in both preventive and corrective measures.

Low myopia

Optical intervention

Axial length

Myopia prevention

Myopia is a significant global health issue, with projections suggesting that by 2050, 49.8% of the world's population, totaling 4.758 billion individuals, will suffer from myopia, including 938 million with high myopia [1]. Low myopia is a transitional stage for children with varying degrees of myopia. Timely intervention at the onset of myopia could significantly reduce the prevalence of high myopia and its complications. Various strategies exist for preventing and managing myopia[2], including behavioral changes[3], environmental adjustments[4, 5], optical interventions[6, 7], pharmaceutical treatments like low-dose atropine[8, 9], and interventions such as repeated low-intensity red light exposure[10]. Optical interventions, such as single vision lenses (SVL), high aspherical lenticule (HAL), and orthokeratology (OK) lenses, are commonly used for children with myopia. This study aimed to compare the 1-year axial length (AL) growth differences in low myopia among three frequently used optical intervention methods: SVL, HAL, and OK lenses. The goal is to determine more suitable and effective optical interventions for preventing and managing low myopia in children, providing empirical evidence to support clinical strategies for myopia control.

Patients

A cohort of 150 children diagnosed with low myopia and receiving treatment at the Optometric Center of the First Affiliated Hospital of Guangxi University of Chinese Medicine during the period from May 1 to August 31, 2022, was included in the analysis. Inclusion criteria included: (1) children aged 7 to 12 years with myopia diagnosed in both eyes through astigmatism and optometry assessments; (2) individuals with a spherical equivalent refraction (SER) of -3.00D or higher and the difference between two eyes less than 1.50D; (3) those with a best corrected visual acuity of 0.8 or superior in both eyes. Exclusion criteria included: (1) participants who have utilized additional preventive measures, including low-intensity red light (LRL), functional training, low-concentration atropine eye drops, traditional Chinese medicine, etc., within the preceding six months apart from the prescribed intervention methods in this study; (2) individuals who are unable to consistently wear glasses or discontinue the use of orthokeratology lenses at their discretion during the intervention period; (3) intervention subjects with preexisting ocular conditions or those unsuitable for glasses or orthokeratology lenses, except for myopia, are not eligible for inclusion. All participants and their guardians provided written informed consent, and the study adhered to the principles of the Helsinki Declaration, as approved by the Ethics Committee of Guangxi University of Traditional Chinese Medicine.

Interventions

SVL group: After a thorough assessment of optometry findings and subjective perception evaluations, a single pair of corrective frame glasses was worn. The glasses were adjusted using the lowest negative spherical lens to optimize visual acuity. Refusing to wear glasses during activities like sleeping, eating, bathing, or engaging in strenuous exercise was recommended. Nonetheless, they should be worn at all other times, with a daily minimum wear time of 8 hours.

HAL group: The application of HAL with foot correction mandates following the optometry principles and wearing time guidelines established for the SVL group. Stellest of Esssilor were employed in this investigation.

OK group: For optimal outcomes, wearing the night-wear OK lenses was imperative without interruption for at least 8 hours overnight. The CRT OK lens utilized in this investigation was individualized with a 6.0 base curve.

Acquisition of specific parameters

Age was calculated as full age. Spherical equivalent refraction (SER = spherical + 1/2 cylindrical) was determined using tropicamide eye drops (0.4/tube, Shenyang Xingqi Eye Medicine Co., Ltd., Liaoning, China) to induce ciliary muscle paralysis. Three drops were administered every 5 minutes, followed by a 30-minute waiting period. Refraction was assessed using an automatic computer refractometer (AR-310A, Nidek, Japan), with three measurements taken and averaged. AL, flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and white-to-white distance (WTW) were measured using IOLmaster (IOLmaster-500, Zeiss, Germany). Non-contact tonometry (NCT) values were obtained with a tonometer (NT-510, Nidec, Japan), with three measurements taken and averaged. All procedures were performed by the same trained personnel. The analysis focused on the specific indicators of the right eye in all study participants.

Statistica analysis

To assess normality, mean ± standard deviation (SD) (x̅ ± s) was calculated using SPSS 24.0. One-way ANOVA tests were conducted to compare age, baseline AL, baseline SER, AL, K1, K2, ACD, WTW, and AL growth across three groups, with independent sample t-test used for pairwise comparisons. Gender distribution and AL growth control rates between HAL and OK lens groups were evaluated through a four-grid chi-square test at a significance level of α = 0.05.

Baseline comparison results revealed no statistically significant differences in gender, age, BCVA, SER, AL, NCT, ACD, corneal curvature, and corneal size among the SVL group, HAL group, and OK lens group (all p > 0.05).

Table 1

Comparisons of parameter baselines of three groups
Parameters		SVL group (n = 50)	HAL group (n = 50)	OK group (n = 50)	F/χ2	p
Sex	Male (n, %)	28 (56.00%)	27 (54.00%)	26 (52.00%)	-	-
Sex	Female (n, %)	22 (44.00%)	23 (46.00%)	24 (48.00%)	0.161	0.923
Age/year		9.62 ± 1.839	9.50 ± 1.741	9.34 ± 1.099	0.388	2.848
Baseline SER/D		-1.405 ± 0.790	-1.595 ± 0.633	-1.717 ± 0.524	2.848	0.984
Baseline AL/mm		24.302 ± 1.098	24.115 ± 0.703	24.323 ± 0.558	0.984	1.377
Corneal K1		43.646 ± 1.894	44.179 ± 1.719	43.838 ± 1.187	1.377	2.145
Corneal K2		42.342 ± 1.712	42.934 ± 1.407	42.626 ± 1.101	2.145	0.121
ACD		3.190 ± 0.119	3.199 ± 0.210	3.187 ± 0.212	0.059	0.942
WTW		12.232 ± 0.767	12.112 ± 0.689	12.232 ± 0.633	0.492	0.612
NCT		14.020 ± 2.360	14.120 ± 2.616	14.380 ± 2.079	0.310	0.734

All data were presented as the mean ± SD. SVL Single vision lens, HAL High aspherical lenticule, OK Orthokeratology, SER Spherical equivalent refraction, D Diopter AL Axial length, K1 Flat keratometry, K2 Steep keratometry, ACD Anterior chamber depth, WTW White-to-white distance, NCT Non-contact tonometry

After a 1-year intervention, Table 2 displays the specific values for the three groups of study participants. The AL growth in the SVL group was 0.516 ± 0.190mm; in the HAL group, it was 0.163 ± 0.113mm, and in the OK group, it was 0.280 ± 0.170mm. The sequence of AL growth was HAL group < OK lens group < SVL group, with statistically significant differences (all p values < 0.001). The HAL group exhibited a 1-year AL growth control rate of 68.41% for children aged 7–12 with low myopia, in contrast to 45.74% in the OK lens group. The HAL group significantly surpassed the OK lens group (p < 0.001). These results indicate that after one year of intervention using three optical methods, both HAL and OK lenses were more successful in controlling axial growth in children with low myopia compared to single lenses. Among these, HAL, followed by OK lenses, demonstrated the most effective control.

Table 2

Effect of 1-year intervention on AL growth and control rate
Parameters		SVL group (n = 50)	HAL group (n = 50)	OK group (n = 50)	F/χ2	p
AL growth/mm	0.516 ± 0.190		0.163 ± 0.113	0.280 ± 0.170	62.224	< 0.001^*
AL growth control rate/%	-		68.41%	45.74%	54.142	< 0.001^*

Data were presented as the mean ± SD. SVL Single vision lens, HAL High aspherical lenticule, OK Orthokeratology, AL axial length, ^* p < 0.05 was considered statistically significant

A t-test was utilized to conduct pairwise comparisons among three groups. Following a one-year intervention, the comparison of AL growth revealed statistically significant differences between the groups, with the HAL group showing less growth than the OK group and the OK lens group showing less growth than the SVL group (all p < 0.001).

A comparative analysis evaluated how gender influences treatment outcomes in three groups. In the SVL group, comprising 28 males and 22 females, the annual increase in AL was 0.505 ± 0.226mm and 0.530 ± 0.131mm, respectively. Statistical analysis indicated no significant difference between the two genders (t = -0.450, p = 0.655). Similarly, in the HAL group of 27 males and 23 females, the 1-year AL growth rates were 0.159 ± 0.114mm and 0.169 ± 0.115mm, respectively, with no statistically significant variance observed (t = -0.314, p = 0.755). In the OK group, comprising 26 males and 24 females, the 1-year AL increases were 0.256 ± 0.151mm and 0.305 ± 0.189mm, respectively, demonstrating no significant distinction (t = -1.015, p = 0.315). Thus, it can be inferred that gender does not influence the efficacy of the three optical intervention methods in managing low myopia.

Correlation analyses examined the relationship between age and AL growth across distinct groups. A significant negative correlation was observed between age and AL growth in the SVL group (r = -0.567, p < 0.001). Conversely, no statistically significant correlations were evident in the HAL group (r = -0.214, p = 0.135) or the OK group (r = -0.188, p = 0.191). These associations are visually depicted in Figs. 1, 2, and 3. The findings indicate that wearing monocular glasses is associated with a negative correlation between age and axial growth, suggesting that older individuals experience slower axial growth. In contrast, both HAL and OK lenses exhibited no significant correlation with age, implying effective prevention and management of axial elongation.

The age range of 7–12 years is a critical period in children's growth and development, marked by the rapid progression of myopia[11, 12]. Low myopia is a significant transitional phase towards high myopia, playing a crucial role in myopia prevention and management. Optical interventions are commonly used to manage myopia in children. This study aims to evaluate and compare the effectiveness of three common optical interventions - SVL, HAL, and OK lenses - in controlling AL growth in children aged 7–12 years. The goal is to objectively distinguish the varying impacts of these optical interventions, providing empirical evidence to guide clinical practice.

Our study has demonstrated the efficacy of HAL and OK lenses in preventing and managing myopia. The annual AL growth is significantly reduced with HAL (0.163 ± 0.113 mm) and OK lenses (0.280 ± 0.170 mm) compared to SVL (0.516 ± 0.190 mm). HAL act as specialized defocusing lenses. In a one-year randomized double-blind controlled trial by Bao et al.[13], involving individuals aged around 10.4 years with moderate to low myopia, the group using HAL exhibited an AL growth of 0.13 ± 0.02 mm, resulting in an AL growth control rate of 64%, whereas the single lens group showed an AL growth of 0.36 ± 0.02 mm. In this study, the one-year AL growth in the SVL group was higher than that of Bao et al., the growth in the HAL group was similar, and the AL control rate (68.41%) was slightly higher than that in the their study. This may be related to the fact that the subjects in this study were low myopia and the mean age was different from subjects of the Bao J et al. (9.5 years old vs. 10.4 years old). Subsequent research by Bao et al. over 2 to 3 years further supported the effectiveness of HAL in controlling myopia [14, 15]. Our study also investigated the impact of gender and age on AL growth with HAL, finding no gender differences or significant age-related correlations. These results suggest that HAL can effectively manage myopia progression in children aged 7 to 12 with low myopia, irrespective of gender or age. However, confirming this conclusion would require larger sample sizes and longer study durations.

The OK lens, a rigid, high-oxygen-permeable contact lens with an anti-geometric design, is commonly utilized for myopia management in children and adolescents. Extensive clinical studies [16, 17] have validated its safety and efficacy. A recent investigation by the research team led by Xiaomei Qu [18]examined 249 children using OK lenses, noting an annual AL growth of 0.21 ± 0.15 mm, slightly lower than the results of our study (0.280 ± 0.170mm). This may be because they studied children with moderate to low myopia, with a baseline SER of -3.03 ± 1.11 diopter (D), as opposed to the low myopia in our study, with a baseline SER of -1.717 ± 0.524 diopter. Similarly, a study on children aged 8–12 with myopia conducted by Shengsong Xu et al. [19] reported a 1-year AL increase of 0.24 ± 0.17 mm in participants with moderate to low myopia. The findings of previous studies [20, 21] have demonstrated a consistent trend of an annual increase in AL ranging from 0.20 to 0.25mm, regardless of lens eccentricity. This pattern is consistently observed across multiple research investigations [22]. However, limited research exists on the therapeutic effects of OK lenses on low myopia. This study seeks to address this gap by comparing the efficacy of OK lenses with other optical interventions to determine the optimal optical strategies for managing low myopia in children.

This study employed a HAL obtained from Stellest of Esssilor Lens Company, characterized by an optical center of 9mm surrounded by 11 rings. The lens design allows a gradient defocusing range from + 3.50D to + 5.50D across the rings [23]. The HAL group demonstrated an AL growth control rate of 68.41% compared to the 45.74% rate observed in the OK group. This discrepancy may be attributed to the more pronounced and consistent peripheral defocus induced by the HAL in cases of low myopia. Nevertheless, further investigation is necessary to confirm this finding.

In conclusion, the one-year comparative study analysis suggests that HAL and OK lenses are more effective than SVL in managing AL growth in children with low myopia. No statistically significant correlation was found between gender and age. Both interventions prove to be successful in the prevention and control of myopia progression. Notably, HAL demonstrates superior efficacy in controlling AL growth, positioning them as a top-tier optical intervention for managing low myopia in pediatric clinical practice.

SVL

Single vision lens

HAL

High aspherical lenticule

Orthokeratology

SER

Spherical equivalent refraction

Diopter

Axial length

Flat keratometry

Steep keratometry

ACD

Anterior chamber depth

WTW

White-to-white distance

NCT

Non-contact tonometry low-intensity red light:LRL

Standard deviation

Acknowledgements

None.

Authors' Contributions

XW designed research; WL and CD conducted research and wrote the paper; WL performed statistical analysis; YZ and YJ collected data and conducted follow-up visits; HL had primary responsibility for final content. All authors read and approved the final manuscript.

Fundings

The study was supported by Guangxi Key Research and Development Plan (No. GuikeAB20238029), Fund Project of Guangxi University of Chinese Medicine Introduced Doctoral Scientific Research (No. 2022BS027).

Ethics approval and consent to participate

The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Guangxi University of Traditional Chinese Medicine, China. All patients have signed an informed consent form to participate in the study and provided permission for the results to be published anonymously.

Consent for publication

Not applicable.

Conflicts of Interest

The authors declare that they have no conflict of interest.

Author details

1 Department of Ophthalmology, the First Affiliated Hospital of Guangxi University of Chinese Medicine, Nanning 530021, Guangxi Zhuang Autonomous Region, China

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No competing interests reported.

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Journal Publication

published 31 Jul, 2024

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Editorial decision: Revision requested
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You are reading this latest preprint version

Three optical intervention methods for low myopia control in children: a one-year follow-up study

Status:

Journal Publication

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Abstract

Figures

Background

Methods

Patients

Interventions

Acquisition of specific parameters

Statistica analysis

Results

Discussion

Conclusion

Abbreviations

Declarations

References

Additional Declarations

Status:

Journal Publication

Version 1