Comparing Myopia Control Effects of Three Different Orthokeratology Lenses and Spectacle Lenses With Highly Aspherical Lenslets in Low Myopia Children

Abstract

Purpose: To compare the effectiveness of three different orthokeratology (OK) lenses and highly aspherical-lenslet spectacle lenses (HAL) for myopia control in young children with low myopia, and to compare the relative corneal refractive power (RCRP) distributions among the three OK lenses with different designs.

Methods: This retrospective study involved 166 children aged eight to 11 years with myopia of −0.50 to −3.00 D treated with ProTong OK lenses with aspheric base curve (APOK), ProTong OK lenses with spherical base curve (SPOK), Euclid OK lenses (EOK), HAL, or single-vision spectacle lenses (SVL). Axial length (AL) was measured at baseline and the 12-month visit. Corneal topography was measured for OK wearers to determine the distance from the apex RCRP profile to its three-quarter-peak.

Results: The axial elongation for the APOK, SPOK, HAL, EOK, and SVL groups were 0.17 ± 0.14 mm, 0.25 ± 0.17 mm, 0.11 ± 0.15 mm, 0.37 ± 0.12 mm, and 0.45 ± 0.16 mm after 12 months, respectively. Axial elongation was significantly slower for the APOK, SPOK, and HAL groups than for the EOK or SVL groups (all P < 0.05); and it was significantly slower in HAL than in SPOK wearers (P < 0.05). 59.5% and 42.9% of HAL and APOK wearers experienced axial elongation of ≤0.15 mm, respectively. The HAL and APOK, SPOK and APOK, or EOK and SVL groups showed no significant differences in axial elongation. Both SPOK and APOK groups had lower 3/4X values than the EOK group.

Conclusions: HAL and APOK wear, relative to EOK or SVL wear, by eight- to 11-year-old children with low myopia led to comparable yet slower axial elongation. APOK and SPOK led to a steeper distribution of the RCRP profile within the pupillary range and yielded better myopia control than EOK.

Translational Relevance: HAL and APOK are recommended for effective myopia control in children aged eight to 11 years with mild myopia.

Introduction

The prevalence of myopia has significantly increased in East and Southeast Asia,¹ with severe complications including myopic maculopathy, glaucoma, and choroidal neovascularization emerging as the primary causes of irreversible vision loss.^2,3 Addressing this issue requires the implementation of effective strategies to delay myopia progression. 

Various optical interventions, including contact lenses and spectacles, have been developed to delay myopia progression.⁴ Among contact lenses, orthokeratology (OK) is widely regarded as effective for slowing axial length (AL) increase, with efficacies of 24% to 80% after one-year wear.^5–13 Re-establishment of the relative corneal refractive power (RCRP) profile by OK lenses causes relative myopic defocus on the peripheral retina, which delays axial elongation.^14,15 The distribution of RCRP can be affected by different lens brands with various zone parameters.^16,17 OK lenses with an aspheric base curve (BC) can increase the RCRP change in the central and paracentral corneal regions and result in less axial elongation than those with spherical BCs.^18,19 However, the impact of the alignment curve (AC) design (aspheric vs. spherical) on the RCRP profile and myopia control effects after OK treatment remains underexplored. 

Besides OK lenses, myopia control spectacles, such as lenses with aspherical lenslets and defocus incorporated multiple segments, have recently gained popularity.⁴ Bao et al.²⁰ reported that the highly aspherical-lenslet spectacle lens (HAL) delayed axial elongation and spherical equivalent refraction (SER) progression by 67% and 64% over one year, respectively, and were more effective in myopia control than defocus incorporated multiple segment lenses in Chinese children.²¹ The reports on the effects of these treatments provide critical insights that assist clinicians in determining the most appropriate options for their patients. 

The effectiveness of myopia control interventions varies significantly among individuals, and age^22–24 and refractive error^25–27 are considered potential influencing factors. Combined data from previous studies revealed that the efficacy of OK lenses with traditional designs in young children with low myopia is less than ideal.^22,28,29 Clinicians have been searching for more effective strategies for this specific population, such as changing the design of OK lenses or using aspherical lenslet spectacles. However, direct comparison of OK lenses with different BC or AC designs (aspheric vs. spherical) and HAL has rarely been reported. 

This study aimed to compare the effectiveness of three different OK lenses and HAL for children aged eight to 11 years with SER below −3.00 D, as well as the RCRP distribution among the three OK lenses with varied designs. The findings are expected to assist clinicians in optimizing myopia control prescriptions for young children with low myopia. 

Methods

Participants

The medical records of children who visited Tianjin Medical University Eye Hospital Optometric Center from January 2022 to June 2023 were reviewed. This study followed the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of Tianjin Medical University Eye Hospital. All participants wearing spectacles or OK lenses for more than 1 year were screened according to the following inclusion criteria: ages of 8–11 years, cycloplegic SER ranging from −0.50 to −3.00 D for both eyes, astigmatism less than −1.00 D in both eyes, anisometropia not exceeding 1.50 D, and best-corrected visual acuity of 20/20 (Snellen; logMAR 0.00) or better in either eye. The exclusion criteria were previous ocular or systemic abnormalities, previous history of ocular surgery, and previous experience with contact lens wear or other antimyopia treatments. 

Lens Fitting

This study used ProTong OK lenses (POK) (Eyebright Co. Ltd, Beijing, China) or Euclid OK lenses (EOK) (Euclid Systems Corporation, Herndon, VA, USA). These two OK lens brands have a four-zone reverse-geometry lens design but different base curve (BC) and alignment curve (AC) designs. The BC zone of EOK is spherical. Its AC zone is also joined by two spherical curves (AC1 and AC2) with a fixed 1.50 D difference. POK lenses include aspheric BC-designed OK lenses (APOK) and spherical BC-designed OK lenses (SPOK), both with an aspheric AC zone. The related details are listed in Table 1. All OK lenses were fitted to both eyes following the manufacturer's guidelines, and the fitting was carried out by the same experienced optometrist. This study did not use any toric OK lenses. The children were directed to wear the lenses for eight hours per night and six nights per week after they were dispensed. They were also scheduled to visit the clinic on one day, one week, as well as one, three, six, nine, and 12 months after the initial lens fitting. The prescriptions of OK lenses were modified when the unaided monocular visual acuity (VA) was worse than 20/25 (Snellen; logMAR 0.10). 

Table 1.

 

Detailed Information About OK Lenses and Spectacle Lenses

 

The participants in the spectacle group wore HAL (Essilor International, Villeurbanne, France) or single-vision spectacle lenses (SVL) (Essilor International). HAL has a spherical front surface, clear central optical zone with a diameter of nearly 9 mm, and a surrounding defocus area of 11 concentric rings formed by contiguous highly aspherical lenslets (3.00–5.00 D).²⁰ A full correction was prescribed for all participants. After lens dispensing, children were required to wear spectacles all day (every day ≥12 hours/day) except when sleeping. Follow-up examinations were conducted at least once every three months after the commencement of lens wear. The prescriptions for spectacle lenses were adjusted if monocular habitual VA was worse than 20/25 (Snellen; logMAR 0.10) or if the residual myopia or astigmatism exceeded 0.50 D.⁶ 

Groups

According to the medical records, the participants selected OK or spectacles as their preferred myopia control strategy. This study included 166 participants who met the inclusion criteria: 28 in the APOK group, 32 in the SPOK group, 35 in the EOK group, 37 in the HAL group, and 34 in the SVL group. 

Ocular Parameter Measurements and Follow-Up Visits

Refraction

At baseline, cycloplegic refraction was performed for all participants. Cycloplegia was induced using four drops of 5 mg/mL (0.5%) tropicamide for each eye with a five-minute interval between drops. Measurements were taken at least 20 minutes after the final drop only when no pupillary response was observed, and the amplitude of accommodation was less than 2.00 D.³⁰ SER was calculated as the sum of the sphere plus one-half of the cylindrical powers. At the 12-month visit, cycloplegic refraction was only performed for participants wearing HAL or SVL. 

Corneal Topography

At baseline, corneal topography was captured using Medmont E300 (Medmont, International Pty. Ltd., Victoria, Australia) for all participants. During the follow-up, corneal topography was captured only for OK wearers. According to the manufacturer's recommendations, at least three maps that provide optimum index values were saved for further analysis. Each map consisted of 32 rings, with 300 data points per ring. The treatment zone size and decentration were calculated as described previously.²⁸ In brief, a difference map was generated by subtracting the baseline tangential curvature map from the tangential curvature map at a 12-month visit. The region where points decreased by more than 0.00 D was identified as the treatment zone, and its boundaries were fitted into a white circle using a custom MATLAB function (MathWorks, Natick, WA, USA) (Fig. 1A). The diameter of the fitted white circle was used to define the treatment zone size. The treatment zone decentration was determined as the distance from the center of the white circle (marked with white across) to the geometric center of the cornea (marked with red across). 

Figure 1.

 

Methods to determine the treatment zone size, the treatment zone decentration, and the RCRP for OK wearers. (A) A difference map was generated to assess the treatment zone size and decentration. The white circle outlines the treatment zone boundary, with the white cross marking its center. The white line “d” denotes the treatment zone diameter, whereas the red cross indicates the corneal apex. The parameter “r” represents the distance of treatment zone decentration. (B) The RCRP map. (C) Representative examples from individual participants of mean RCRP profiles within their own pupillary diameters in the APOK, SPOK, and EOK groups.

As mentioned previously, the RCRP map (Fig. 1B) was obtained by subtracting the apical corneal refractive power from the power at each point on the 12-month axial power map.²⁸ The pupil diameter was determined from the map captured under ambient mesopic room illumination.³¹ The values of points on the RCRP map within the individual pupillary diameter were averaged along each ring to derive the mean RCRP profile, and a quadratic curve was fitted using the mean values for the OK groups. Representative examples of mean RCRP profiles within the pupillary diameters of individual participants in the OK groups are shown in Figure 1C. In the RCRP profile, Y represents the maximum RCRP within the pupil area, with distinct Y values indicating varying RCRP. The corresponding X values denote the distance from the corneal apex. Based on our previous study, the 3/4X value—corresponding to three-quarters of the maximum RCRP (denoted as 3/4Y) within the pupillary area—is an important index for describing how rapidly an RCRP profile reaches its three-quarter peak level.³² The summed values of the RCRP profile within the pupil diameter of an individual were calculated and referred to as RCRPsum, representing the total corneal power shift within the pupillary range. 

AL Measurement

AL was measured for all participants using noncontact optical biometry (Lenstar LS900; Haag-Streit, Koeniz, Switzerland) after cycloplegia, both at baseline and the 12-month visit. Three consecutive measurements were obtained while ensuring an inter-measurement difference of no more than 0.02 mm¹³ and averaged to obtain a representative value for further analysis. Axial elongation was defined as the difference between the measurements recorded at baseline and the 12-month visit. 

Statistical Analysis

The normality of the data was assessed using the Shapiro-Wilk test. One-way analysis of variance (ANOVA) was used to compare the three or five groups when normality was confirmed. The χ² test was used to compare the male/female ratio and proportions of participants with axial elongation of ≤0.15 mm among groups. Bonferroni corrections for significant outcomes were used for post-hoc comparisons. Data from the right eye were used for statistical analysis, and all analyses were performed using R software (version 3.2.2 http://www.R-project.org/). P values <0.05 denoted statistical significance. 

Results

A total of 166 participants were included in the study, and their ages ranged from 8 to 11 years old. Baseline data related to age, sex distribution, SER, and AL did not differ significantly among the APOK, SPOK, EOK, HAL and SVL groups (all P > 0.05, Table 2). The habitual VAs (logMAR) for the APOK, SPOK, HAL, EOK and SVL groups were 0.01 ± 0.03, 0.02 ± 0.03, −0.0 1± 0.03, 0.00 ± 0.04, and −0.02 ± 0.03 at the 12-month visit, respectively (P > 0.05). No adverse events were recorded for the groups. 

Table 2.

 

Baseline Information for Participants in Five Groups

 

Changes in Topographic Map Parameters in OK Groups

Table 3 shows the changes in topographic map parameters for the three OK groups after one year of follow-up. The treatment zone sizes for the APOK, SPOK and EOK groups were 4.60 ± 0.54, 4.56 ± 0.77, and 4.28 ± 0.35 mm, respectively. The treatment zone decentration was 0.26 ± 0.27 mm for the APOK group, 0.21 ± 0.13 mm for the SPOK group, and 0.19 ± 0.10 mm for the EOK group. No significant differences were found in the treatment zone size and decentration among the three OK groups (both P > 0.05). The pupil diameters did not differ significantly among the APOK, SPOK and EOK groups at 4.75 ± 0.78 mm, 4.52 ± 0.59 mm, and 4.65 ± 0.62 mm, respectively (P > 0.05). The values of RCRPsum were not significantly different for wearers of the three types of OK lenses (7.75 ± 6.51, 8.07 ± 6.60, and 7.78 ± 7.80 D*mm² for the APOK, SPOK, and EOK groups, respectively; P > 0.05). Here, Y in the RCRP profile represented the maximum RCRP within the pupil area, and no significant differences in the Y-value were observed among the three OK groups (1.26 ± 0.70, 1.43 ± 0.70, and 1.55 ± 0.57 D for the APOK, SPOK, and EOK groups, respectively; P > 0.05). No significant differences were observed in the 3/4Y value among the three groups (APOK, 1.00 ± 0.52 D; SPOK, 1.11 ± 0.51 D; and EOK, 1.32 ± 0.71 D; P > 0.05). The 3/4X values for the APOK (1.66 ± 0.48 mm) and SPOK (1.77 ± 0.34 mm; P > 0.05) groups were similar; both were significantly lower than that for the EOK group (2.15 ± 0.18 mm; both P < 0.01). 

Table 3.

 

Changes in Topographic Map Parameters After One Year of OK Treatment

 

Changes in AL

Figure 2 shows significant differences in the AL elongation over one year among the five groups (P < 0.01). Subsequent Bonferroni-adjusted post-hoc comparisons revealed that the magnitude of axial elongation was significantly lower for the APOK (0.17 ± 0.14 mm), SPOK (0.25 ± 0.17 mm), and HAL (0.11 ± 0.15 mm) groups than for the EOK (0.37 ± 0.12 mm) or SVL (0.45 ± 0.16 mm) group (all P < 0.05). Participants in the HAL group showed significantly slower axial elongation than those in the SPOK group (P < 0.05). Axial elongation in the HAL group was slightly slower than that in the APOK group, but the difference was not statistically significant (P > 0.05). There were no statistically significant differences in axial elongation between the EOK and SVL or the SPOK and APOK groups (both P > 0.05). Furthermore, the progression of SER was significantly slower for the HAL than for the SVL group (−0.24 ± 0.27 D vs. −1.07 ± 0.64 D; P < 0.05) 

Figure 2.

 

Axial elongation over one year in the APOK, SPOK, EOK, HAL, and SVL groups. **P < 0.01, ***P < 0.001.

Rates of AL Elongation

As shown in Table 4, the proportions of participants in the five groups with AL elongation of ≤0.15 mm were significantly different (χ² = 50.78, P < 0.05). Bonferroni-adjusted post-hoc comparisons of groups revealed that the HAL group had a higher proportion of participants with axial elongation of ≤0.15 mm (59.5%) than the APOK (42.9%) and SPOK (25.0%) groups (both P < 0.05). However, no participants in the EOK and SVL groups had axial elongation of ≤0.15 mm. Axial elongation of 0.15 to 0.40 mm was observed in 50.0%, 56.3%, 60.0%, 37.8%, and 47.1% of participants in the APOK, SPOK, EOK, HAL, and SVL groups, respectively. Furthermore, 40.0% of EOK users and 52.9% of SVL users experienced more than 0.40 mm of axial elongation, whereas only 2.7% of HAL users experienced rapid myopic progression. Overall, HAL demonstrated the most effective myopia control over one year in the present study. 

Table 4.

 

Comparison of Rates of AL Elongation for the Five Groups Over one Year of Follow-Up

 

Discussion

This retrospective study found that young children with low initial myopia treated with HAL achieved a comparable reduction in axial elongation to those using APOK lenses. During the one-year follow-up, 59.5% of the children in the HAL group and 42.9% of those fitted with APOK lenses experienced axial elongation of less than 0.15 mm. These findings underscore the superior efficacy of HAL in controlling myopia progression, followed closely by APOK lenses. Additionally, wearing of APOK and SPOK lenses designed with an aspheric AC zone led to a steeper distribution of the RCRP profile within the pupil area and a greater delay of progression of axial elongation than the EOK lenses. However, the BC design (spherical vs. aspheric) had insignificant effects on axial elongation and RCRP distribution for the APOK and SPOK lenses with an aspheric AC. 

The effectiveness of myopia control by wearing overnight OK lenses has been extensively evaluated, showing variability among different participant groups.^4,33 Axial elongation was lower for children receiving OK treatment than for those receiving other treatments, with differences ranging from 0.04 to 0.42 mm.³⁴ This was in agreement with what was observed in the current study; the mean difference in AL elongation for all OK wearers and controls was 0.19 mm per year. The mean annual AL changes for the APOK (0.17 mm) and SPOK (0.25 mm) groups in the current study were close to those previously reported by Liu et al.¹⁸ (0.19 mm/year for APOK vs. 0.29 mm/year for SPOK). However, this study did not observe any statistically significant differences in axial elongation between the two groups, indicating that the design of the BC (spherical vs. aspheric) had no significant effect on axial elongation between the two lenses with aspheric AC. Children wearing EOK lenses in the present study had more rapid axial elongation (0.37 mm/year) than was previously reported³⁵ and did not show significant positive myopia control effects. This corroborates the conclusion of our previous study that EOK lenses with 6.2 mm-back optic zone diameters were relatively ineffective for myopia control in eight- to 11-year-old children with SER below −2.50 D.²⁸ Previous studies have indicated that various brands of traditional vision-shaping treatment OK lenses with four-zone reverse-geometry designs demonstrated comparable effectiveness in slowing axial elongation.^36–39 However, this study found that axial elongation in the APOK and SPOK groups was significantly lower than that observed in the EOK group. These inconsistencies may be attributed to variations in participant age, initial refractive error, and study designs. Additionally, discrepancies in lens curvature parameters may partly explain the differences observed between the current and prior findings. The main design difference between the POK (APOK and SPOK) and EOK lenses is that the AC zone of the former is aspheric, while that of the latter is spherical. Current research focuses on optimizing the design of the BC zone to enhance myopia control effects⁴⁰; however, the impact of AC zone morphology on myopia control outcomes remains underexplored. 

HAL spectacle lenses significantly mitigate myopia progression in children.^20,41–43 In this study, the average axial elongation and SER progression after one year of using HAL lenses were 0.11 mm and −0.24 D, respectively. These corresponded to a 76% reduction in AL increase (a difference of 0.34 mm) and a 78% reduction in SER change (a difference of 0.83 D) relative to that of the SVL group. These were supported by the findings reported by Bao et al.,²⁰ who observed a 0.23 mm/year less AL increase and a 0.53 D/year less SER progression in those wearing HAL relative to those wearing SVL. The efficacies were 64% and 67% for reduction, respectively. The disparity in relative reduction efficacy may be attributable to the higher mean age (10.4 years) of the participants in the study by Bao et al.⁴¹ relative to the cohort in the present study (9.4 years). Myopia progression tends to slow down with increasing age. Longitudinal studies extending over two to three years have confirmed the sustainability of myopia control effects for HAL,^41,42 and this optical modality effectively retards eye growth in eyes with myopia to levels that are similar to, or even lower than, those observed in age-matched emmetropic eyes.⁴⁴ 

There is sufficient evidence that OK and HAL lenses are safe and effective options for myopia control,⁴ whereas the reports on whether their effects differ remain limited. Yu et al.²⁵ found that corneal refractive therapy (CRT) OK lenses and HAL were similarly effective in managing myopia from −1.00 to −2.00 D over one year. However, CRT OK lenses demonstrated a superior effect in retarding axial elongation relative to HAL for individuals with SER values of −2.00 to −3.00 D. Inconsistent with these, the present study demonstrated that children with initial myopia below −3.00 D in the HAL group showed significantly slower axial elongation than those fitted with SPOK and EOK lenses. The different effects on myopia control reported by the two studies may be attributed to several factors. First, the children in the study by Yu et al.²⁵ were older on average (10.3 years) than those in the present study. Second, the mean axial elongation of the control group in the study by Yu et al.²⁵ (0.35 mm) was lower than the 0.45 mm observed in the SVL group of the present study, suggesting inherently slower axial growth in their participants. Third, Yu et al.²⁵ used CRT lenses, whereas this study used vision-shaping treatment lenses; previous studies have reported different myopia control effects for these two types of lenses.^38,45 Besides, this study found that the axial elongation (0.11 mm) in the HAL group was marginally lower than that (0.17 mm) for the APOK group, although the difference was not statistically significant. Similarly, a recent study proposed that, the mean axial elongation for the myopic eyes was 0.17 mm for the OK group and 0.10 mm for the HAL group, with no significant difference between the two groups.⁴⁶ Furthermore, an annual AL increase in Chinese children aged eight to 11 years typically ranges from 0.16 mm to 0.41 mm.⁴⁷ Therefore an annual AL increase of ≤0.15 mm can be considered indicative of minimal myopia progression. Drawing upon the methodology used by Tang et al.,⁴⁸ this study analyzed the proportion of individuals with an annual AL increase of ≤0.15 mm. The results revealed that the HAL group had a higher proportion of participants with axial elongation of less than 0.15 mm (59.5%) relative to the APOK (42.9%) and SPOK (25.0%) groups during the one-year follow-up. The synthesis of the available findings indicates that HAL provides the most effective myopia control for children aged eight to 11 years old with low initial myopia, followed by APOK and SPOK lenses. 

Imposing myopic defocus on the peripheral retina is one of the critical mechanisms underlying myopia control with OK and HAL lenses.^49,50 The RCRP resulting from central corneal flattening and mid-peripheral corneal steepening can reflect the extent of peripheral myopic defocus after OK treatment.^45,51 The RCRP distribution after corneal reshaping by OK lenses is of great significance to AL increase.^14,15,45 In our previous study, we developed the 3/4X index to capture how quickly an RCRP profile within the pupillary zone can increase to its three-quarter peak level and reported that a lower 3/4X value correlated strongly with a lower axial elongation after one year of OK treatment.³² In this study, the RCRP profiles for both the SPOK and APOK groups, characterized by lower 3/4X values, reached their three-quarter peak levels at shorter distances from the apex relative to the EOK group. Based on this, the SPOK and APOK lenses led to a steeper RCRP profile distribution within the pupillary diameter, contributing to the observed reduction in axial elongation. This may partly explain the superior efficacy of SPOK and APOK lenses over EOK lenses in controlling axial elongation among eight- to 11-year-old children with low initial myopia. To yield a “volume of myopic defocus,” HAL was designed with contiguous highly aspherical lenslets (3.00–5.00 D) distributed in an annular zone surrounding a central distance correction zone.²⁰ Lenslet array structure plays a significant role in providing different myopic defocus signals at different eccentricities.⁵⁰ We hypothesize that one reason for the differences in myopia control effects between the OK lens and HAL is that HAL has a fixed defocus power. In contrast, the defocus power of the OK lens is dynamic and mainly determined by the refractive error, corneal topography, and reshaping time of participants. Moreover, a recent study used multispectral refraction topography to measure the peripheral refraction difference value as an indicator of myopic defocus and demonstrated that the amount of myopic defocus resulting from the OK lens and HAL exhibited regional distribution differences,²⁵ which may be another reason contributing to the differences in their myopia control effects. However, the actual peripheral retinal defocus induced by the OK lens and HAL was not directly measured in this study because of limitations in current detection equipment. Further research is needed to precisely quantify and compare the differences in myopic defocus on the peripheral retina between the OK and HAL groups. 

Each optical intervention offers distinct advantages and drawbacks. OK lenses are often considered cosmetically appealing, enhancing satisfaction and positively influencing peer perceptions.⁵² Spectacle intervention is relatively simple to implement and represents the least invasive option relative to OK lenses. To achieve optimal treatment outcomes, it is recommended to wear HAL for at least 12 hours daily.⁴¹ The findings of this study suggest that treatment with HAL or APOK may be recommended as an optimal strategy for myopia control in children aged eight to 11 years with low myopia. Nevertheless, the peripheral lenslets in HAL led to reduced peripheral temporal and superior contrast sensitivity and diminished contraction motion perception in the periphery relative to OK lenses.⁵³ Wearing OK lenses may be suitable if children have specific needs related to global scene recognition and movement. Therefore clinicians should tailor myopia control strategies based on individual characteristics and the needs of children and their guardians. 

This study had several limitations. First, it was based on retrospective data. A randomized clinical trial with a larger sample size is warranted to further compare the treatment effects of different OK lenses and HAL. Second, the follow-up duration in this study was only one year, necessitating further research to assess long-term effects. Third, this study did not directly measure and compare the differences in myopic defocus on the peripheral retina between the OK and HAL groups due to the lack of testing equipment. 

Conclusions

The current study showed that HAL was the most effective myopia control method for eight- to 11-year-old children with low initial myopia, followed closely by APOK lenses over the one-year follow-up in this study. Notably, 59.5% and 42.9% of children in the HAL and APOK groups experienced axial elongation of <0.15 mm. The effectiveness the different types of OK lenses also differed, suggesting that each optical intervention offers distinct advantages for specific populations. Therefore a personalized myopia control strategy, considering factors such as initial age, myopic refraction, and individual needs, may enhance the effectiveness of myopia management in children. 

Acknowledgments

The authors thank Emmanuel Eric Pazo, Tianjin Medical University Eye Hospital, for critical enhancement of the English style of this article. 

Supported by National Natural Science Foundation of China, Grant/Award Numbers: 82070929. 

Disclosure: N. Li, None; L. Luobu, None; B. Du, None; W. Lin, None; R. Wei, None