Myopia has emerged as a significant concern impacting the visual health of children and adolescents on a global scale. According to research conducted by Holden BA et al., it is projected that by the year 2050, the worldwide prevalence of myopia and high myopia will experience a substantial increase, affecting approximately 5 billion and 1 billion individuals, respectively, with particularly high prevalence rates observed in East Asia[1]. The persistent rise in myopia incidence, coupled with the escalation of complications associated with high myopia, is anticipated to exert complex socio-economic repercussions [2]. Consequently, the prevention of myopia onset and the management of axial length elongation have become critically important [3].

Orthokeratology (Ortho-K) is a procedure that involves the overnight application of specially designed reverse geometry rigid gas permeable contact lenses to achieve temporary corneal reshaping and reduce myopia during the day[4,5]. In children with mild to moderate myopia, Ortho-K has demonstrated visual correction efficacy ranging from 80% to 92%[6,7]. Nonetheless, its efficacy in controlling myopia progression may not match its corrective efficacy. The therapeutic effect of Ortho-K in decelerating axial elongation is reported to range from 43% to 63%. Despite the use of Ortho-K, approximately 15% of children continue to exhibit rapid axial elongation exceeding 0.36 mm per year.[8,9].

In recent years, adjunctive interventions such as low-concentration atropine eye drops, modification of the back optical zone diameter (BOZD) of orthokeratology (Ortho-K) lenses, and low-level red-light therapy (RLRL) have been proposed to augment the myopia control efficacy of Ortho-K. Zhao et al. [10] reported that after one year of treatment with either atropine orthokeratology (AOK) or Ortho-K lenses in children aged 5-14 years, the axial length (AL) increased by 0.14 mm and 0.29 mm, respectively. Another study involving children aged 8-12 years [11] demonstrated that after one year of treatment, the AOK group exhibited a 17% reduction in AL growth (0.20 mm vs. 0.24 mm). Research conducted by Xiong et al. [12] indicated that for children whose eyes elongated by at least 0.50 mm within one year of Ortho-K wear, the combination of RLRL therapy with Ortho-K significantly reduced axial elongation compared to Ortho-K alone. Additional studies have suggested that decreasing the BOZD can enhance the extent and degree of mid-peripheral corneal steepening, thereby decelerating axial elongation [13-15].

Most existing studies primarily compare a single intervention against a control group, thereby lacking direct "head-to-head" comparisons. Traditional meta-analyses are limited to comparing two interventions at a time and often fail to assess multiple treatments concurrently. Consequently, most meta-analyses offer only statistical insights into the efficacy of individual interventions. Clinically, it is common to combine two or more interventions to treat myopia, particularly in cases of rapidly progressive myopia. Previous research has indicated that combined interventions may have additive effects in the prevention and control of myopia; however, these findings require further empirical validation.

This study employs a retrospective approach to evaluate the efficacy of various treatment strategies in managing axial elongation in children aged 8-12 years who experience rapid axial progression following Ortho-K lens wear. The objective is to provide a scientific foundation for the development of personalized myopia control plans.

Participants were categorized into four distinct groups based on the intervention strategy:1) OK group: Participants continued using Ortho-K lenses without any additional intervention; 2) OKA group: Participants used Ortho-K lenses supplemented with 0.01% atropine eye drops administered nightly in both eyes; 3) OKBC group: At the 12-month interval, participants transitioned to Ortho-K lenses featuring a reduced optical zone, maintaining the same lens brand and other parameters; 4) OKRL group: Participants used Ortho-K lenses in conjunction withe repeated low-level red-light (RLRL) therapy administered twice daily in both eyes. Measurements were systematically recorded at 6 and 12 months following the intervention.(Figure 1. Participants flowchart.) Ortho-K Lenses: This study did not impose restriction the design or brand of Ortho-K lenses. Lens replacement was permissible to satisfy refractive and fitting criteria, provided the brand remained unchanged from that used prior to enrollment. The OKBC group was uniquely permitted to modify the back optical zone diameter parameter of the Ortho-K lenses.

0.01% Atropine Eye Drops: These were supplied by Shenyang Xingqi Eye Medicine Co., Ltd. The prescribed usage involved instilling one drop in each eye 10 minutes before the nightly application of Ortho-K lenses .

Repeated low-level red-light Therapy Device: This device was supplied by Suzhou Xuanjia Photoelectric Technology Co., Ltd. [16]. The prescribed usage protocol involved administering the therapy, twice daily, with each session lasting 3 minutes and a minimum intercal of 4 hours between sessions, conducted 7 days a week.

Inclusion Criteria:

1) The initial fitting age is between 8-12 years, irrespective of gender; 2) The spherical equivalent refraction (SE) of both eyes at the initial fitting falls within the manufacturer's approved range of -6.00D to -0.50D; 3) The best corrected visual acuity of both eyes is ≥1.0 (Snellen); 4) The ability to ensure overnight Ortho-K lens wear for a duration of 8 to 10 hours; 5) No prior history of ocular trauma or surgery; 6) No prior history of acute or chronic ocular inflammation, such as keratoconjunctivitis or abnormal tear film; 7) The ability to meticulously adhere to instructions for lens care and attend regular follow-up examinations; 8) The standard use of other myopia progression interventions, such as 0.01% atropine or red-light therapy as prescribed; 9) Comprehensive follow-up data; 10) At least one eye exhibits an annual axial length elongation of >0.30 mm during the first year of Ortho-K lens wear.

Exclusion Criteria:

1) Axial length elongation less than 0.30 mm in both eyes during the first year of Ortho-K treatment; 2) Incidence of significant complications during the study period, such as recurrent corneal inflammation; 3) Incomplete data or cases lost to follow-up; 4) SE of either eye less than -6.00D, or astigmatism greater than -2.00D; 5) Unstable vision during Ortho-K treatment, characterized by multiple instances of vision below 0.2 (LogMAR); 6) Change in the brand of Ortho-K lens.

This study utilized a retrospective data collection approach. To prevent the influence of non-independent data from both eyes of a single participant on statistical analyses, data from only one eye per subject were included in the final analysis. The selection criterion prioritized data from the right eye; however, if the right eye did not satisfy the primary inclusion criterion of "annual axial elongation >0.30 mm," data from the left eye were used instead. This study was conducted in accordance with the Declaration of Helsinki and received approval from the Ethics Committee of the Tianjin Medical University Eye Hospital. Informed consent was obtained from the guardians of all participating children.

Children aged 8-12 years with myopia who have worn orthokeratology (OK) lenses for at least 1 year, with axial length elongation >0.3mm in the past 12 months, indicating progressive myopia despite OK lens wear. Both male and female participants are eligible, with no gender restriction.