One-year results of the Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study: a prospective randomised clinical trial

Machine learning-based nomogram to predict poor response to overnight orthokeratology in Chinese myopic children: A multicentre, retrospective study

PURPOSE

To develop and validate an effective nomogram for predicting poor response to orthokeratology.

METHODS

Myopic children (aged 8-15 years) treated with orthokeratology between February 2018 and January 2022 were screened in four hospitals of different tiers (i.e. municipal and provincial) in China. Potential predictors included 32 baseline clinical variables. Nomogram for the outcome (1-year axial elongation ≥0.20 mm: poor response; <0.20 mm: good response) was computed from a logistic regression model with the least absolute shrinkage and selection operator. The data from the First Affiliated Hospital of Chengdu Medical College were randomly assigned (7:3) to the training and validation cohorts. An external cohort from three independent multicentre was used for the model test. Model performance was assessed by discrimination (the area under curve, AUC), calibration (calibration plots) and utility (decision curve analysis).

RESULTS

Between January 2022 and March 2023, 1183 eligible subjects were screened from the First Affiliated Hospital of Chengdu Medical College, then randomly divided into training (n = 831) and validation (n = 352) cohorts. A total of 405 eligible subjects were screened in the external cohort. Predictors included in the nomogram were baseline age, spherical equivalent, axial length, pupil diameter, surface asymmetry index and parental myopia (p < 0.05). This nomogram demonstrated excellent calibration, clinical net benefit and discrimination, with the AUC of 0.871 (95% CI 0.847-0.894), 0.863 (0.826-0.901) and 0.817 (0.777-0.857) in the training, validation and external cohorts, respectively. An online calculator was generated for free access (http://39.96.75.172:8182/#/nomogram).

CONCLUSION

The nomogram provides accurate individual prediction of poor response to overnight orthokeratology in Chinese myopic children.

Interventions for myopia control in children: a living systematic review and network meta-analysis

RATIONALE

The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Interventions to slow its progression are needed in childhood, when myopia progression is most rapid. This is a review update, conducted as part of a living systematic review.

OBJECTIVES

To assess the comparative efficacy and safety of interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of interventions according to their efficacy. To produce a brief economic commentary, summarising economic evaluations.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and three trial registers. The latest search date was 19 February 2024.

ELIGIBILITY CRITERIA

We included randomised controlled trials (RCTs) of optical, pharmacological, light therapy and behavioural interventions for slowing myopia progression in children, up to 18 years old.

OUTCOMES

Critical outcomes were progression of myopia (mean difference (MD) in the change in spherical equivalent refraction (SER, dioptres (D)), and axial length (AL, mm) in the intervention and control groups at one year or longer), and difference in the change in SER and AL following cessation of treatment (rebound).

RISK OF BIAS

We assessed the risk of bias (RoB) for SER and AL using the Cochrane RoB 2 tool.

SYNTHESIS METHODS

We followed standard Cochrane methods. We rated the certainty of evidence using the GRADE approach for change in SER and AL at one and two years. We used the surface under the cumulative ranking curve (SUCRA) to rank the interventions for all available outcomes.

INCLUDED STUDIES

We included 104 studies (40 new for this update) that randomised 17,509 children, aged 4 years to 18 years. Most studies were conducted in China or other Asian countries (66.3%), and North America (14.4%). Eighty-four studies (80.8%) compared myopia control interventions against inactive controls. Study durations ranged from 12 months to 48 months.

SYNTHESIS OF RESULTS

Since most of the networks in the NMA were poorly connected, our estimates are based on direct (pairwise) comparisons, unless stated otherwise. The median change in SER for controls was -0.65 D (55 studies, 4888 participants; one-year follow-up). These interventions may reduce SER progression compared to controls: repeated low intensity red light (RLRL: MD 0.80 D, 95% confidence interval (CI) 0.71 to 0.89; SUCRA = 93.8%; very low-certainty evidence); high-dose atropine (HDA (≥ 0.5%): MD 0.90 D, 95% CI 0.62 to 1.18; SUCRA = 93.3%; moderate-certainty evidence); medium-dose atropine (MDA (0.1% to < 0.5%): MD 0.55 D, 95% CI 0.17 to 0.93; NMA estimate SUCRA = 75.5%; low-certainty evidence); low dose atropine (LDA (< 0.1%): MD 0.25 D, 95% CI 0.16 to 0.35; SUCRA = 53.2%; very low-certainty evidence); peripheral plus spectacle lenses (PPSL: MD 0.45 D, 95% CI 0.16 to 0.74; SUCRA = 50.2%; very low-certainty evidence); multifocal soft contact lenses (MFSCL: MD 0.27 D, 95% CI 0.18 to 0.35; SUCRA = 49.9%; very low-certainty evidence); and multifocal spectacle lenses (MFSL: MD 0.14 D, 95% CI 0.08 to 0.21; SUCRA = 30.8%; low-certainty evidence). The median change in AL for controls was 0.33 mm (58 studies, 9085 participants; one-year follow-up). These interventions may reduce axial elongation compared to controls: RLRL (MD -0.33 mm, 95% CI -0.37 to -0.29; SUCRA = 98.6%; very low-certainty evidence); HDA (MD -0.33 mm, 95% CI -0.35 to -0.30; SUCRA = 88.4%; moderate-certainty evidence); MDA (MD -0.24 mm, 95% CI -0.34 to -0.15; NMA estimate SUCRA = 75.8%; low-certainty evidence); LDA (MD -0.10 mm, 95% CI -0.13 to -0.07; SUCRA = 36.1%; very low-certainty evidence); orthokeratology (ortho-K: MD -0.18 mm, 95% CI -0.21 to -0.14; SUCRA = 79%; moderate-certainty evidence); PPSL (MD -0.13 mm, 95% CI -0.21 to -0.05; SUCRA = 52.6%; very low-certainty evidence); MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09; SUCRA = 45.6%; low-certainty evidence); and MFSL (MD -0.06 mm, 95% CI -0.09 to -0.04; SUCRA = 26.3%; low-certainty evidence). Ortho-K plus LDA probably reduces axial elongation more than ortho-K monotherapy (MD -0.12 mm, 95% CI -0.15 to -0.09; SUCRA = 81.8%; moderate-certainty evidence). At two-year follow-up, change in SER was reported in 34 studies (3556 participants). The median change in SER for controls was -1.01 D. The ranking of interventions to reduce SER progression was close to that observed at one year; there were insufficient data to draw conclusions on cumulative effects. The highest-ranking interventions were: HAD (SUCRA = 97%); MDA (NMA estimate SUCRA = 69.8%); and PPSL (SUCRA = 69.1%). At two-year follow-up, change in AL was reported in 33 studies (3334 participants). The median change in AL for controls was 0.56 mm. The ranking of interventions to reduce axial elongation was similar to that observed at one year; there were insufficient data to draw conclusions on cumulative effects. The highest-ranking interventions were: ortho-K plus LDA (SUCRA = 94.2%); HAD (SUCRA = 96.8%); and MDA (NMA estimate SUCRA = 88.4%). There was limited evidence on whether cessation of myopia control therapy increases progression beyond the expected rate of progression with age. Adverse events and treatment adherence were not consistently reported. Two studies reported quality of life, showing little to no difference between intervention and control groups. We were unable to draw firm conclusions regarding the relative costs or efficiency of different myopia control strategies in children.

AUTHORS' CONCLUSIONS

Most studies compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. These interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. Less evidence is available for two years and beyond; uncertainty remains about the sustained effect of these interventions. Longer term and better quality studies comparing myopia control interventions alone or in combination are needed, with improved methods for monitoring and reporting adverse effects.

FUNDING

Cochrane Eyes and Vision US Project is supported by grant UG1EY020522, National Eye Institute, National Institutes of Health.

REGISTRATION

The previous version of this living systematic review is available at doi: 10.1002/14651858.CD014758.pub2.

Influence of back optic zone diameter on corneal morphology with orthokeratology lenses

OBJECTIVE

This study aimed to compare the changes in corneal morphological characteristics in corneal topography assessments performed after wearing orthokeratology (OK) lenses with different back optic zone diameters (BOZDs). These changes included the change ratios of the apical corneal power (ACP), the maximum relative corneal refractive power (mRCRP), and the treatment zone diameter (TZD).

METHODS

Data from 133 children with myopia (average age 9.50 ± 1.23 years) treated at Fudan University Eye and Ear, Nose, and Throat Hospital were retrospectively analyzed. All participants wore the same brand of tangent-design OK lens (corneal refractive therapy, CRT). According to the BOZD, the patients were divided into two groups, of 5.0 and 6.0 mm BOZD, respectively. Corneal topography was analyzed at baseline, as well as 1 day, 1 week, and 1 month after wearing the lenses, and the change ratios of ACP, mRCRP, and TZD were compared between the two groups.

RESULTS

The change ratio of the ACP did not differ significantly between the BOZD 5.0 and 6.0 groups after 1 day or 1 week of lens wear (P = 0.170 and P = 0.113, respectively). However, after 1 month of lens wear, the change ratio of the ACP in the BOZD 5.0 group was significantly larger than that in the BOZD 6.0 group (P < 0.001). After 1 month of lens wear, the mRCRP along the horizontal and vertical meridians was higher (P < 0.05) and the TZD was significantly smaller (P < 0.001) in the BOZD 5.0 group than in the BOZD 6.0 group.

CONCLUSION

In CRT OK lenses, a small BOZD lens can produce faster corneal shaping, a larger mRCRP, and a smaller TZD, which may have a better effect on slowing ocular axial length elongation. The lens parameters are also a factor affecting the TZD.

Impact of back optic zone diameter (BOZD) in orthokeratology on axial length elongation: A meta-analysis and systematic review

PURPOSE

Myopia has emerged as a significant public health concern. Recent studies have demonstrated that Orthokeratology (Ortho-K) can effectively decelerate axial length (AL) growth, with eyes possessing smaller back optical zone diameters (BOZD) exhibiting greater effectiveness compared to those with larger BOZD. This study aims to analyze the impact of Ortho-K with varying BOZD.

METHOD

This systematic review involved the retrieval of articles from eight databases: PubMed, Embase, Web of Science, Cochrane, CNKI, Wanfang, Sinomed, and VIP, covering the period from each database's inception to January 2024. It compared axial length (AL) changes between smaller and larger back optic zone diameters (BOZD). Review Manager 5.4 was used to statistical analysis and the results presented as weighted mean differences and 95% confidence intervals (CI). This review adheres to the PRISMA guidelines.

RESULT

This systematic review included two randomized controlled trials (RCTs) and five cohort studies (CS), analyzing a total of 702 eyes (352 eyes are treated with Ortho-K and BOZD ≤ 5.5 mm, 350 eyes are treated with Ortho-K and BOZD ≥ 6.0 mm). The findings indicate that the Ortho-K with smaller BOZD significantly reduces AL growth [WMD = -0.13, 95 %CI (-0.16 to -0.10), P < 0.001].

CONCLUSION

The Ortho-K with smaller BOZD prove more effective in controlling myopic AL growth compared with larger BOZD. However, in clinical practice, it is necessary to comprehensively evaluating factors such as patient age, myopia diopter, pupil diameter, higher-order aberration, treatment zone area, and corneal eccentricity to achieve optimized outcomes in improving naked-eye vision and myopia controlling.

Comparison of two-year myopia control efficacy between spectacle lenses with highly aspherical lenslets and orthokeratology lenses

PURPOSE

To compare the two-year efficacy of spectacle lenses with highly aspherical lenslets (HAL) and orthokeratology (OK) lenses in managing myopia in children.

METHODS

This retrospective study examined medical records from the Affiliated Eye Hospital of Wenzhou Medical University, involving 1683 HAL users and 1192 OK users. Participants were children aged 8-13 with a refractive error of -0.50 to -6.00 D. They were divided by age into younger (8-10 years) and older (11-13 years) groups and further divided into low myopia (-0.50 to -3.00 D) and moderate myopia (<-3.00 to -6.00 D) subgroups. The participants were included in either the 1-year or 2-year follow-up group based on the length of their follow-up records. The change in axial length (AL) was compared between the HAL and OK groups using t-tests and multiple linear regression analysis.

RESULTS

In the younger group, HALs yielded significantly slower AL elongation than did the OK lenses at both the 1-year (HAL: 0.16 ± 0.19 mm; OK: 0.22 ± 0.17 mm; p < 0.001) and 2-year follow-ups (HAL: 0.32 ± 0.27 mm; OK: 0.37 ± 0.24 mm; p = 0.009). In the older group, the AL changes did not significantly differ by lens at the 1-year (p = 0.782) or 2-year (p = 0.239) follow-up. Among the low myopia subgroup, the HAL users consistently exhibited smaller AL changes than did the OK users across all follow-ups (p < 0.05), except at the 2-year follow-up in the olders (p = 0.414). For the moderate myopia subgroup, the OK lenses yielded significantly slower AL changes at the 2-year follow-up (younger: p = 0.013; older: p = 0.01), although no significant differences were found at the 1-year follow-up (younger: p = 0.635; older: adjusted: p = 0.143).

CONCLUSIONS

HALs are significantly more effective than OK lenses in controlling AL elongation in younger children with low myopia, while both treatments show similar effectiveness in older children. For moderate myopia, OK lenses are preferred for superior long-term control.

Association between axial elongation and corneal topography in children undergoing orthokeratology with different back optic zone diameters

PURPOSE

To explore the associations between myopia defocus dosage (MDD), aberration coefficients (primary spherical aberration and coma), and axial elongation in children undergoing orthokeratology (ortho-k) with back optic zone diameters (BOZD) of 5 mm and 6 mm over 2 years.

METHODS

Data from 80 participants from two ortho-k studies were analyzed: 22 and 58 children wore lenses with 5-mm and 6-mm BOZD, respectively. Four MDD metrics were calculated from corneal topography data over a 5-mm pupil for the 1-month and 24-month visits: the circumferential, flat, steep, and volumetric MDD. Corneal primary spherical aberration and comatic aberrations were also extracted from topography data over a 5-mm pupil. Linear mixed modelling was performed to explore the associations between the MDD, corneal aberrations, and axial elongation over 2 years, while controlling for confounding factors (e.g., baseline age and sex).

RESULTS

Participants in the 5-mm BOZD group displayed less axial elongation than the 6-mm BOZD group over 2 years (0.15 ± 0.21 mm vs. 0.35 ± 0.21 mm, P < 0.001). A greater volumetric MDD was observed in the 5-mm BOZD group compared with the 6-mm BOZD group at the 1- and 24-month visits (both P < 0.001). No significant differences were observed between the two groups for the other MDD metrics or corneal aberration coefficients (all P > 0.05). Less axial elongation was associated with a greater volumetric MDD at the 1- and 24-month visits (both β = -0.01, P < 0.001 and P = 0.001), but not with any other MDD metrics or corneal aberrations (all P > 0.05).

CONCLUSIONS

The volumetric MDD over a 5-mm pupil after 1 month of ortho-k lens wear was associated with axial elongation after 24 months, and may be a useful predictor of future axial elongation in children undergoing ortho-k.

Myopia control strategies: A systematic review and meta-meta-analysis

PURPOSE

To summarise pooled estimates of the efficacies of various myopia control interventions, as drawn from published meta-analyses.

METHOD

PubMed, SCOPUS and Web of Science were searched from inception to February 2024 for systematic reviews and meta-analyses reporting treatment effects of various myopia control strategies. The qualities of the included meta-analyses were assessed using the 16-item A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2. An intervention was defined as having a clinically significant effect if it resulted in a change in spherical equivalent refraction (SER) of ≥0.50 D/year or axial length (AL) change of ≤-0.18 mm/year.

RESULTS

A total of 38 studies were identified. The overall respective changes in SER and AL, mean difference (95% CI) were high-concentration (≥0.5%) atropine 0.67 D (0.58-0.77) and -0.24 mm (-0.36 to -0.11); moderate-concentration (>0.05% to <0.5%) atropine 0.48 D (0.34-0.62) and -0.23 mm (-0.27 to -0.19); low-concentration (0.01%, 0.025%, 0.05%) atropine 0.33 D (0.23-0.43) and -0.14 mm (-0.19 to -0.09); orthokeratology -0.47 mm (-0.66 to -0.28); peripheral plus soft contact lenses 0.30 D (0.18-0.42) and -0.35 mm (-0.62 to -0.08); peripheral plus spectacles 0.77 D (0.40-1.14) and -0.43 mm (-0.78 to -0.08); multifocal spectacles 0.21 D (0.11-0.31); repeated low-level red light therapy 0.55 D (0.46-0.65) and -0.25 mm (-0.29 to -0.20); outdoor time 0.17 D (0.16-0.18) and -0.04 mm (-0.06 to -0.01).

CONCLUSION

High and moderate concentrations of atropine, orthokeratology, peripheral plus spectacles and repeated low-level red light demonstrated clinically significant effects on slowing AL elongation, while high and moderate concentrations of atropine, peripheral plus spectacles and repeated low-level red light demonstrated clinically significant effects on slowing SER progression.

Artificial intelligence-assisted fitting method using corneal topography outcomes enhances success rate in orthokeratology lens fitting

PURPOSE

Based on ideal outcomes of corneal topography following orthokeratology (OK), an innovative machine learning algorithm for corneal refractive therapy (CRT) was developed to investigate the precision of artificial intelligence (AI)-assisted OK lens fitting.

METHODS

A total of 797 eyes that had been fitted with CRT lenses and demonstrated good lens centration with plus power ring intact in their topography were retrospectively included. A comprehensive AI model included spherical refraction, keratometry readings, eccentricity, corneal astigmatism, horizontal visible iris diameter, inferior-superior index, surface asymmetry index, surface regularity index and 8-mm chordal corneal height difference. A simplified AI model omitted the latter four parameters. Correlation and disparity in predicted lens parameters between the AI prediction and manufacturer's conventional lens fitting method were compared.

RESULTS

There was overall no significant difference between AI predicted parameters and the final ordered parameters (p > 0.05). The horizontal return zone depth (RZD1, p = 0.022) and vertical return zone depth (RZD2, p < 0.001) values suggested by the conventional method were significantly lower, while the horizontal landing zone angle (LZA1) was significantly larger (p = 0.002) than those of the final ordered lens. The AI predicted parameters were significantly correlated to those of the final ordered lens (p < 0.01), with the correlation coefficients of base curve radius (BCR), RZD1, RZD2, LZA1, vertical LZA (LZA2) and total lens diameter (TD) being 0.958, 0.708, 0.773, 0.697, 0.654 and 0.730, respectively, for the comprehensive AI model. The correlation coefficients were higher in RZD2, LZA1 and TD with the AI model as compared to conventional method.

CONCLUSIONS

Compared with the conventional method, AI predicted lens parameters exhibit less disparity and improved accuracy, with a potential to facilitate more efficient and precise CRT OK lens fitting.

Safety of repeated low-level red-light therapy for myopia: A systematic review

PURPOSE

Establishing the safety profile of repeated low-level red-light (RLRL) therapy is necessary prior to its widespread clinical implementation.

METHODS

We conducted a systematic review (International Prospective Register of Systematic Reviews, CRD42024516676) of articles across seven databases from inception through February 10, 2024, with keywords related to myopia and RLRL therapy. Pooled safety outcomes and risk-to-benefit ratios were reported, and incidence of side effects was compared with other antimyopia interventions.

RESULTS

Among 689 screened articles, 20 studies (2.90 %; median duration 9 months, longest 24 months) were analysed, encompassing 2380 participants aged 3-18 years and 1436 individuals undergoing RLRL therapy. Two case reports described an identical patient with reversible decline in visual acuity and optical coherence tomography (OCT) abnormalities, completely resolved 4 months after treatment cessation. No cases of permanent vision loss were reported. Temporary afterimage was the most common ocular symptom following treatment, resolving within 6 minutes in reported studies. The number needed to harm outweighed the number needed to treat by a ratio of 12.7-21.4 for a person with -3D to -8D myopia treated with RLRL therapy. Incidence of side effects from RLRL was 0.088 per 100 patient-years (95 % confidence interval, 0.02-0.50).

CONCLUSIONS

No irreversible visual function loss or ocular structural damage was identified with RLRL. Fundus photography and OCT before and during therapy, alongside home monitoring of visual acuity and duration of afterimages, are necessary to identify side effects. Further adequately powered studies of longer duration are needed to evaluate long-term safety of RLRL.

Effects of different orthokeratology lens designs on slowing axial length elongation in children with myopia

AIM

To elucidate whether differences exist in the impact on retarding the elongation of axial length (AL) among children with myopia when utilizing orthokeratology (ortho-k) lenses employing the corneal refractive therapy (CRT) design versus those employing the vision shaping treatment (VST) design.

METHODS

This retrospective clinical trial aimed to collect and analyze AL data from individuals who wore ortho-k lenses for three years. A total of 654 subjects were enrolled and prescribed one of the three specific brands of ortho-k lenses: CRT, Euclid, and Mouldway. The study's primary focus was to compare the rates of AL elongation and myopic progression across these three brands of ortho-k lenses.

RESULTS

In the 3-year follow-up, the AL elongation exhibited variations of 0.73±0.36 mm in the CRT lens group, 0.59±0.37 mm in the Euclid lens group, and 0.63±0.38 mm in the Mouldway lens group. A noteworthy disparity emerged between the CRT and Mouldway groups (P<0.01), as well as between the CRT and Euclid groups (P<0.001). Additionally, it was observed that 32.1% of participants who wore CRT lenses experienced a decelerated progression of myopia, in contrast to 47.2% in the Euclid group and 44.4% in the Mouldway group. Statistical analyses revealed a statistically significant distinction between the CRT and Euclid groups (P<0.01), and similarly, the CRT group demonstrated a statistically significant difference when compared to the Mouldway group (P<0.05).

CONCLUSION

Ortho-k lenses represent a pragmatic strategy for mitigating the advancement of myopia. In contradistinction to ortho-k lenses utilizing the CRT design, those employing the VST design exhibited a more favorable impact regarding retarding AL elongation.

Analysis of corneal surface shape following overnight orthokeratology with different optical zone diameters

Purpose

This study analyzed the corneal surface shape following overnight orthokeratology with different optical zone diameters.

Methods

A total of 82 eyes belonging to 41 myopic children who completed 1 month of the orthokeratology (ortho-k) lens wear at the Eye Hospital of Wenzhou Medical University from January 2022 to January 2023 were retrospectively analyzed. According to the size of the base curve (BC) of ortho-k lens, patients were divided into BC 5.0 and BC 6.0 groups. The changes in decentration distance and corneal refraction of the two groups after the ortho-k lens wear were analyzed. Independent sample t-tests were used to compare these two outcome measures between the two groups.

Results

The decentration distance of BC 5.0 group (0.37 ± 0.19 mm) was significantly lower than that of BC 6.0 group (0.49 ± 0.25 mm, t = -2.330, p = 0.022). In the BC 5.0 group, the direction of decentration was superonasal in 3 cases, inferonasal in 2 cases, inferotemporal in 21 cases, and superotemporal in 6 cases. In the BC 6.0 group, the direction of decentration was superonasal in 2 cases, inferonasal in 2 cases, inferotemporal in 27 cases, and superotemporal in 19 cases. The optical zone area (8.19 ± 2.96 mm2) and reverse curve zone area (30.05 ± 6.74 mm2) in the BC 5.0 group were significantly lower than in the BC 6.0 group (10.42 ± 2.03 mm2, t = -4.043, p < 0.001; 38.21 ± 4.77 mm2, t = -6.422, p < 0.001). The change in the rate of refraction in the horizontal direction in BC 5.0 group were significant higher than in BC 6.0 group.

Conclusion

Base curve 5.0 mm ortho-k lens is better positioned than BC 6.0 mm lens. A small BC ortho-k forms a smaller optical zone and reverse curve area, which might get a greater aiameter of alignment curve to facilitate positioning better than the traditional BC lens. In addition, a small BC lens increases positive refraction in the peripheral area, resulting in a greater negative pressure than the traditional BC lens.

Comparison of the Effects of Orthokeratology and Highly Aspherical Lenselets in Achieving Myopia Control and Defocus in Adolescents

OBJECTIVES

To compare the control effectiveness and periretinal defocus between orthokeratology (OK) and highly aspherical lenslets (HAL) in adolescents with myopia.

METHODS

In this prospective study, 211 children (211 right eyes) were enrolled in Beijing Ming Vision and Ophthalmology between October 2022 and February 2023. Based on the myopia correction method, participants were divided into three groups: OK, HAL, and single-vision spectacles (SVS). They were further divided into two subgroups according to the spherical equivalent (SE), namely, subgroup A with -1.0≤SE≤-2.0 D and subgroup B with -2.0

RESULTS

Axial length growth in those with OK lenses and HAL was lower than what was observed for those with SVS after 6, 9, and 12 months. Comparison of the difference in AL change between OK and HAL was not statistically significant with -1.0≤SE≤-2.0 D. The myopic defocus of RDV270° to 300° in group HAL was higher than that in group OK, the difference was statistically significant ( P <0.05), and in other regions, the myopic defocus was higher in the group OK. Em, SRI (corneal regularity index), variation in cell area, and corneal thickness were significantly associated with shaping force.

CONCLUSIONS

Orthokeratology is one of the most effective optical treatments for controlling myopia, and the factors that affect the corneal shaping force under different corneal parameters are different. For mild myopia, HAL can achieve the same effectiveness as OK.

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Key Words Collapse

MESH Headings

• Humans
• Orthokeratologic Procedures/methods
• Adolescent
• Myopia/therapy
• Myopia/physiopathology
• Male
• Prospective Studies
• Female
• Axial Length, Eye/pathology
• Refraction, Ocular/physiology
• Child
• Eyeglasses
• Visual Acuity/physiology
• Contact Lenses
• Follow-Up Studies
• Cornea/pathology
• Cornea/physiopathology

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Grants Collapse

Affiliation(s)

Jia Yu Ming Vision and Ophthalmology (J.Y., Y.Z.), Jianguomen Branch Clinic, Beijing, China; and Eye School of Chengdu University of TCM (Y.G., Y.Z.), Ineye Hospital of Chengdu University of TCM, Chengdu, Sichuan, China
Yujuan Guo
Yuehua Zhou

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Efficacy of orthokeratology lens with the modified small treatment zone on myopia progression and visual quality: a randomized clinical trial

BACKGROUND

To evaluate the long-term effectiveness of orthokeratology (ortho-K) lenses with small treatment zone (STZ) or conventional treatment zone (CTZ) in controlling axial elongation in children with myopia as well as the impact on visual quality. We also sought to determine the effect of retinal visual signal quality on axial elongation.

METHODS

This is a prospective randomized controlled study. A total of 140 participants (age ranging from 8 to 12 years) were randomly assigned to wear either STZ or CTZ ortho-K lenses. STZ ortho-K lenses design was achieved by changing the depth of reverse zone and the sagitta height of the optical zone. Using the IOL-Master 500, axial length (AL) was measured at baseline and after 6, 12 and 18 months of ortho-K treatment. Spherical aberration (SA) and corneal topographic parameters were obtained by the Pentacam anterior segment analyzer at baseline and the 1-month follow-up visit, and optical qualities were assessed by optical quality analysis system-II (OQAS-II) at baseline and after 1 month of lens wearing. Optical quality parameters mainly included the modulation transfer function (MTF) cutoff, Strehl ratio (SR), objective scattering index (OSI), and predicted visual acuity (PVA).

RESULTS

A total of 131 participants completed the study, including 68 in the STZ group and 63 in the CTZ group. The STZ group had significantly reduced AL elongation compared to the CTZ group after treatment (12 months: 0.07 ± 0.11 mm vs. 0.14 ± 0.12 mm, P = 0.002; 18 months: 0.17 ± 0.15 mm vs. 0.26 ± 0.16 mm, P = 0.002). The topography in the STZ group showed a smaller treatment zone (TZ) diameter (2.50 ± 0.23 mm vs. 2.77 ± 0.18 mm, P < 0.001), a wider defocus ring width (2.45 ± 0.28 mm vs. 2.30 ± 0.30 mm, P = 0.006), and larger values of total amount of defocus (119.38 ± 63.71 D·mm2 vs. 91.40 ± 40.83 D·mm2, P = 0.003) and total SA (0.37 ± 0.25 μm vs. 0.25 ± 0.29 μm, P = 0.015), compared with the CTZ group. Objective visual quality decreased in both groups (P < 0.001). This was evidenced by a greater decrease in MTF cutoff (- 14.24 ± 10.48 vs. - 10.74 ± 9.46, P = 0.047) and SR values (- 0.09 ± 0.07 vs. - 0.06 ± 0.07, P = 0.026), and an increase in OSI value (0.84 ± 0.72 vs. 0.58 ± 0.53, P = 0.019). PVA9% decreased significantly in the STZ group but not the CTZ group. A statistically significant negative correlation was found between the changes in total SA and MTF cutoff values (r =  - 0.202, P = 0.025). AL changes were associated with sex, change of MTF cutoff value, increment of total SA and TZ area.

CONCLUSIONS

Compared with CTZ ortho-K lenses, STZ ortho-K lenses significantly inhibited axial elongation in children with myopia while moderately reducing their objective visual quality. Axial elongation was affected by retinal visual quality, and it may be a possible mechanism for ortho-K slowing myopia progression. Trial registration This trial is registered at Chinese Clinical Trial Registry on November 5, 2019 with trial registration number: ChiCTR1900027218. https://www.chictr.org.cn/showproj.html?proj=45380.

Effect of Lens Deviation on Peripheral Defocus and Optic Quality in Adolescents With Moderate and Severe Myopia

OBJECTIVES

The aim of this study was to analyze the effects of lens deviation on peripheral defocus and optic quality in adolescents with moderate and severe myopia.

METHODS

This prospective study enrolled 81 children (81 eyes). The spherical equivalent was -5.0≤SE≤-6.0 diopter. The participants were divided into two subgroups based on their eccentricity (inferior temporal) after wearing the lenses for 12 months. Between them, the low eccentric subgroup (A) had a total eccentric distance of less than 0.5 mm, and the moderate and severe eccentric subgroup (B) had a total eccentric distance of ≥0.5 mm. Peripheral defocus and eccentricity were measured before and after wearing the lenses, and the Spearman test was used to compare the parameters.

RESULTS

Parameters such as the total peripheral defocus (TRDV) were significantly lower in subgroup B than in subgroup A after 12 months of orthokeratology lens usage. The axial length growth (ΔAL) in subgroup A was higher than that in subgroup B. Axial length growth, TRDV, and other parameters were significantly associated with eccentricity. The modulation transfer function cutoff and Strehl ratio were also significantly associated with eccentricity.

CONCLUSIONS

Greater eccentricity within a certain range can induce greater periretinal defocus and improve the ΔAL.

The efficacy of orthokeratology lenses with smaller back optic zone diameter in myopia control. A meta-analysis

PURPOSE

This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects.

METHOD

A meta-analysis was registered in PROSPERO (CRD42023408184). A comprehensive systematic database search was conducted, encompassing PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Ovid, CNKI and CBM, to identify relevant studies up to 25 March 2023. The primary inclusion criteria for this meta-analysis were studies that investigated the myopia control effect of OK lenses with a small optical treatment area (≤5 mm). To assess the quality of the retrieved articles, two researchers evaluated them using the Cochrane bias risk assessment criteria. The primary outcome measures were the changes in axial length (AL) and refractive error, using the weighted mean differences (WMD) and 95% confidence intervals (CI) to assess differences between small and traditional back optical treatment zone groups in terms of these outcomes.

RESULTS

The analysis encompassed five eligible studies, with a 1 year duration. The average difference in AL between the groups was 0.12 mm (WMD = -0.12, 95% CI [-0.16, -0.09], p < 0.00001). Likewise, the average difference in refractive error between the two groups was 0.44 D (WMD = 0.44, 95% CI [0.30, 0.57], p < 0.00001). None of the studies reported severe adverse events.

CONCLUSIONS

Current evidence suggests that OK lenses with smaller back optical treatment zone are more effective in preventing myopia progression than traditional lenses. However, a longer-term evaluation is warranted.

Myopia management algorithm. Annexe to the article titled Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute

Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in later life in the near future. Because myopia can cause serious complications and vision loss, it is critical to create and prescribe effective myopia treatment solutions that can help prevent or delay the onset and progression of myopia. The scientific understanding of myopia's causes, genetic background, environmental conditions, and various management techniques, including therapies to prevent or postpone its development and slow its progression, is rapidly expanding. However, some significant information gaps exist on this subject, making it difficult to develop an effective intervention plan. As with the creation of this present algorithm, a compromise is to work on best practices and reach consensus among a wide number of specialists. The quick rise in information regarding myopia management may be difficult for the busy eye care provider, but it necessitates a continuing need to evaluate new research and implement it into daily practice. To assist eye care providers in developing these strategies, an algorithm has been proposed that covers all aspects of myopia mitigation and management. The algorithm aims to provide practical assistance in choosing and developing an effective myopia management strategy tailored to the individual child. It incorporates the latest research findings and covers a wide range of modalities, from primary, secondary, and tertiary myopia prevention to interventions that reduce the progression of myopia.

Altering optical zone diameter, reverse curve width, and compression factor: impacts on visual performance and axial elongation in orthokeratology

PURPOSE

To investigate the effects of modifications in back optical zone diameter (BOZD), reverse curve width (RCW), and compression factor (CF) on refractive error changes and axial elongation in myopic children undergoing orthokeratology (ortho-k) over a 12-month period.

METHOD

In this retrospective study, data from 126 myopic children undergoing ortho-k fitting were analyzed. Subjects were categorized into four distinct groups based on lens design parameters: Group A (BOZD 6.0 mm, RCW 0.6 mm, CF 0.75 D); Group B (BOZD 6.0 mm, RCW 0.6 mm, CF 1.25 D); Group C (BOZD 5.4 mm, RCW 0.9 mm, CF 1.25 D); and Group D (BOZD 5.0 mm, RCW 1.1 mm, CF 1.25 D). The study evaluated uncorrected visual acuity (UCVA), corneal topography, and axial length (AL) at intervals, using Linear Mixed Models (LMMs) for time-based changes, and ANOVA or Kruskal-Wallis tests for group differences in AL elongation. A multivariable regression analysis identified factors independently associated with AL elongation.

RESULTS

Within the first day and week, all four groups displayed significant improvements in UCVA and alterations in corneal curvature, which subsequently stabilized. Although UCVA variations between groups were subtle, Group D had less corneal curvature change than Groups A and B initially and exhibited significantly less AL elongation after one year. No significant difference in corneal curvature change or AL elongation was observed between Group C and the other groups. Multiple regression analysis indicated that older baseline age, greater baseline spherical equivalent refractive error, and smaller BOZD were associated with less AL elongation.

CONCLUSION

The study reveals a positive correlation between BOZD and axial length growth over the 12-month period. A pure 0.5 D CF increment demonstrates a nonsignificant impact. This study provides new ideas into optimizing the parameters of ortho-k lenses.

Study of association between corneal shape parameters and axial length elongation during orthokeratology using image-pro plus software

BACKGROUND

The aim was to validate the correlation between corneal shape parameters and axial length growth (ALG) during orthokeratology using Image-Pro Plus (IPP) 6.0 software.

METHODS

This retrospective study used medical records of myopic children aged 8-13 years (n = 104) undergoing orthokeratology. Their corneal topography and axial length were measured at baseline and subsequent follow-ups after lens wear. Corneal shape parameters, including the treatment zone (TZ) area, TZ diameter, TZ fractal dimension, TZ radius ratio, eccentric distance, pupil area, and pupillary peripheral steepened zone(PSZ) area, were measured using IPP software. The impact of corneal shape parameters at 3 months post-orthokeratology visit on 1.5-year ALG was evaluated using multivariate linear regression analysis.

RESULTS

ALG exhibited significant associations with age, TZ area, TZ diameter, TZ fractal dimension, and eccentric distance on univariate linear regression analysis. Multivariate regression analysis identified age, TZ area, and eccentric distance as significantly correlated with ALG (all P < 0.01), with eccentric distance showing the strongest correlation (β = -0.370). The regressive equation was y = 1.870 - 0.235a + 0.276b - 0.370c, where y represents ALG, a represents age, b represents TZ area, and c represents eccentric distance; R2 = 0.27). No significant relationships were observed between the TZ radius ratio, pupillary PSZ area, and ALG.

CONCLUSIONS

IPP software proves effective in capturing precise corneal shape parameters after orthokeratology. Eccentric distance, rather than age or the TZ area, significantly influences ALG retardation.

The effect of the back optic zone diameter on the treatment zone area and axial elongation in orthokeratology

PURPOSE

To investigate the influence of corneal parameters on the treatment zone area (TZA) after Corneal Refractive Therapy (CRT) with a 5.0-mm back optical zone diameter (BOZD) were worn and to compare changes in the axial length (AL) with traditional 6.0-mm BOZD lenses.

METHODS

This retrospective study involved 146 subjects (7-12 years) who wore orthokeratology (ortho-K) lenses for one year: 86 subjects were treated with CRT 5.0-mm lenses, and 60 subjects were treated with CRT 6.0-mm lenses. The TZA was measured after one year of ortho-K treatment. Both TZA and AL elongation after wearing the two kinds of lenses was compared. The parameters were recorded in the CRT 5.0 group: flat K, steep K, corneal toricity, e value, and anterior corneal elevation values at the 3-, 4-, and 5-mm chords along the principal meridians of the superior, inferior, nasal, and temporal sides. The relationships between these data and the TZA were analyzed.

RESULTS

The TZA was 12.90 ± 5.15 mm2 and 20.61 ± 4.54 mm2, and the AL elongation was 0.15 ± 0.18 mm and 0.26 ± 0.18 mm in the CRT 5.0 group and the CRT 6.0 group, respectively (all p < 0.001). The one-year AL elongation was significantly associated with initial age and the TZA (r =  - 0.394, 0.393; all p < 0.001) in the CRT 5.0 group. The following corneal parameters were found to have statistically significant correlations with the TZA: the e value, difference in corneal elevation (nasal-temporal at the 3-, 4-, and 5-mm chord), and the absolute value of elevation difference (nasal-temporal at the 3- and 4-mm chord and inferior-superior at the 3-, 4-, and 5-mm chord). The e value was the only relevant factor for the TZA by multiple regression analysis (unstandardized β = 14.219, p = 0.008). In the CRT 6.0 group, the one-year AL elongation was statistically significantly associated only with initial age (r =  - 0.605, p = 0.005), but not with the TZA (p = 0.161).

CONCLUSIONS

A smaller TZA induced by a smaller BOZD may be beneficial for retarding AL elongation in children undergoing ortho-K treatment. The morphology and eccentricity of the cornea may show effects on the TZA.

Comparison of three VST orthokeratology lenses in axial length growth and average corneal reshaping in myopia children: A retrospective self-controlled study

Purpose

To determine the differences in myopia control efficiency and corneal reshaping between three different brands of orthokeratology (OK) lenses (Lucid, Euclid, and Alpha).

Method

We retrospectively reviewed subjects who started simultaneously using different brands of OK lenses. For each participant, every 6 months in the 19 months of following, the changes in axial length (AL), horizontal and vertical maximum distances of the treatment zone (HMDTZ and VMDTZ), width of the high convex zone (WHCZ), distance of decentration, and horizontal and vertical components of the decentration vector were measured. The average values of the above data, the average value of the decentration vector (ADV), and the average value of decentration calculated algebraically (ADA) were calculated.

Results

All the three pairs (Lucid (n = 46) vs. Euclid (n = 46): groups Lucid-versus-Euclid-Lucid (LE-L) and LE-E), Lucid (n = 50) vs. Alpha (n = 50): groups LA-L and LA-A), and Euclid (n = 17) vs. Alpha (n = 17): groups EA-E and EA-A) showed good comparability. Regarding the change in AL during 19 months, none of the pairs showed significant differences (LE-L:0.27 ± 0.24 mm, LE-E:0.31 ± 0.24 mm (p = 0.68); LA-L:0.36 ± 0.26 mm, LA-A:0.36 ± 0.27 mm (p = 0.85); EA-E:0.34 ± 0.27 mm, EA-A:0.41 ± 0.28 mm (p = 0.63)). Regarding treatment zone, Lucid showed the largest HMDTZ and VMDTZ (both p < 0.05). Regarding the WHCZ, none of the pairs showed significant differences. For the ADV and ADA, Lucid had more ADV and ADA than Euclid (ADV: LE-L:0.73 ± 0.44 mm, LE-E:0.55 ± 0.45 mm, p < 0.05; ADA: LE-L:0.80 ± 0.41 mm, LE-E:0.63 ± 0.44 mm, p < 0.05), and the remaining pairs showed no significant difference. For the overall cohort with 113 eyes, the change in AL was weakly correlated with both ADV and ADA (both p < 0.05). Regarding the ADV/ADA, all pairs showed no significant differences, indicating equal lens position stability.

Conclusion

After OK, there were no significant differences between the different pairs of the three brands in AL growth, WHCZ, or lens position stability, although Lucid had a larger treatment zone than Euclid and Alpha, and Lucid had more decentration than Euclid. A larger lens decentration were weakly related to less AL growth.

Impact of pupil and defocus ring intersection area on retinal defocus

PURPOSE

With the rising prevalence of myopia, especially among the young, orthokeratology (Ortho-K) stands out as a promising approach, not only to reduce myopia but also to control the progression of axial length (AL). This study examined how the intersection area between the pupil and defocus ring influenced retinal defocus and axial growth after Ortho-K.

METHODS

A case-control study was conducted with 100 participants (100 eyes). Both AL and the refraction difference value (RDV), that is, the peripheral refractive error measured with respect to the central value after wearing Ortho-K lenses, were determined. Subjects were categorised into two groups based on the size of the intersection area after 3 months of lens wear: Group A (<4.58 mm2 ) and Group B (≥4.58 mm2 ).

RESULTS

Group B demonstrated significantly lower changes in AL and RDV at 30-40° and 40-53° compared with Group A after 3 months of lens wear (all p < 0.05). After 6 months of lens wear, Group B showed significantly lower changes in AL and RDV in the 40-53° region compared with Group A (all p < 0.05). Correlation analysis revealed that as the intersection area increased, the changes in AL and RDV at 0-53°, 30-40° and 40-53° eccentricity decreased after both 3 and 6 months of lens wear (all p < 0.01).

CONCLUSIONS

A larger intersection area between the pupil and defocus ring within a certain time period can cause a greater amount of myopic defocus at 30-53° from the fovea. The results suggest that a larger intersection area might lead to more effective control of axial growth.

One-year results for myopia control of orthokeratology with different back optic zone diameters: a randomized trial using a novel multispectral-based topographer

AIM

To present the 1-year results of a prospective cohort study investigating the efficacy, potential mechanism, and safety of orthokeratology (ortho-k) with different back optic zone diameters (BOZD) for myopia control in children.

METHODS

This randomized clinical study was performed between Dec. 2020 and Dec. 2021. Participants were randomly assigned to three groups wearing ortho-k: 5 mm BOZD (5-MM group), 5.5 mm BOZD (5.5-MM group), and 6 mm BOZD (6-MM group). The 1-year data were recorded, including axial length, relative peripheral refraction (RPR, measured by multispectral refractive topography, MRT), and visual quality. The contrast sensitivity (CS) was evaluated by CSV-1000 instrument with spatial frequencies of 3, 6, 12, and 18 cycles/degree (c/d); the corneal higher-order aberrations (HOAs) were measured by iTrace aberration analyzer. The one-way ANOVA was performed to assess the differences between the three groups. The correlation between the change in AL and RPR was calculated by Pearson's correlation coefficient.

RESULTS

The 1-year results of 20, 21, and 21 subjects in the 5-MM, 5.5-MM, and 6-MM groups, respectively, were presented. There were no statistical differences in baseline age, sex, or ocular parameters between the three groups (all P>0.05). At the 1-year visit, the 5-MM group had lower axial elongation than the 6-MM group (0.07±0.09 vs 0.18±0.11 mm, P=0.001). The 5-MM group had more myopic total RPR (TRPR, P=0.014), with RPR in the 15°-30° (RPR 15-30, P=0.015), 30°-45° (RPR 30-45, P=0.011), temporal (RPR-T, P=0.008), and nasal area (RPR-N, P<0.001) than the 6-MM group. RPR 15-30 in the 5.5-MM group was more myopic than that in the 6-MM group (P=0.002), and RPR-N in the 5-MM group was more myopic than that in the 5.5-MM group (P<0.001). There were positive correlations between the axial elongation and the change in TRPR (r=0.756, P<0.001), RPR 15-30 (r=0.364, P=0.004), RPR 30-45 (r=0.306, P=0.016), and RPR-N (r=0.253, P=0.047). The CS decreased at 3 c/d (P<0.001), and the corneal HOAs increased in the 5-MM group (P=0.030).

CONCLUSION

Ortho-k with 5 mm BOZD can control myopia progression more effectively. The mechanism may be associated with greater myopic shifts in RPR.

Deep neural network with self-attention based automated determination system for treatment zone and peripheral steepened zone in Orthokeratology for adolescent myopia

PURPOSE

The aim of this study is to develop an automatic model based on deep learning techniques for determining the Treatment Zone (TZ) and Peripheral Steepened Zone (PSZ) following Orthokeratology (OK) treatment.

METHODS

A total of 1346 corneal topography maps were included in the study. A deep neural network based on the Segformer architecture was constructed to automatically detect TZ and PSZ. The model was optimized and trained multiple times, and the areas of TZ, PSZ, and TZ decentration were calculated based on the segmentation results.

RESULTS

The mean Intersection over Union (mIoU) of the overall segmentation results of the model reached over 97% after multiple training with different optimization methods, and the IoU for the TZ and PSZ segmentation tasks were 98.08% and 94.54% in test set, respectively. Moreover, the model demonstrated high consistency with the expert annotation for the TZ segmentation, while a significant difference was found in the PSZ segmentation and expert annotation due to several interference factors.

CONCLUSION

This study presents an efficient and repeatable system for clinical research, based on a deep neural network that accurately determines TZ and PSZ after OK treatment using the Segformer architecture. However, further deployment validation may be necessary.

Comparison of the clinical efficacy of orthokeratology and 0.01% atropine for retardation of myopia progression in myopic children

OBJECTIVE

To compare the clinical efficacy of orthokeratology (ortho-k) and 0.01% atropine for retardation of myopia progression in myopic children.

METHODS

This was a retrospective cohort study. A total of 282 patients, aged 8-17 years, were enrolled, including 100 children treated with ortho-k, 84 with 0.01% atropine, and 98 with single-vision spectacles. During the follow-up of 1 year, ortho-k wearers were examined at 1 day, 1 week, 1 month, 3 months after treatment, and thereafter every 3 months, while the others were examined every 3 months by measurements of uncorrected vision, intraocular pressure, refractive power, slit-lamp microscopy, corneal topography, and the lens fitting when necessary. The axial length was measured every 6 months.

RESULTS

Patients with ortho-k had stable uncorrected vision after 1 month of lens wear, all reaching 0 logMAR. The annual axial elongation was 0.23 ± 0.19 mm, 0.22 ± 0.20 mm, and 0.39 ± 0.27 mm in the ortho-k, atropine, and spectacle groups, respectively, with significant difference (F = 23.251, P = 0.000). The axial length was delayed to increase by 41.03% and 43.59% within a year in patients with ortho-k and atropine, respectively, as compared to patients with spectacles (F = 0.006, P = 0.936). The elongation was ≤ 0.3 mm in 69.0% and 66.7% of patients in the two groups, respectively, versus 38.8% in the spectacle group (χ2 = 17.251, P = 0.000). During the follow-up, the rate of corneal staining was 11.0% and 2.0% in the ortho-k and spectacle groups, respectively (χ2 = 8.076, P = 0.003). The use of atropine did not increase corneal staining, but the incidence of related photophobia was 4.8%. No other serious complications were observed.

CONCLUSION

Ortho-k lenses and 0.01% atropine can achieve similar efficacy of myopia retardation, which was significantly better than that obtained with single-vision spectacles, in myopic children. The risk of corneal staining after ortho-k wear may be slightly higher than that with spectacles, but could be well controlled.

Study on Related Factors of the Treatment Zone After Wearing Paragon CRT and Euclid Orthokeratology Lenses

OBJECTIVE

To explore the influence factors of the treatment zone diameter (TZD) and its relationship with axial length growth (ALG) after wearing Paragon CRT and Euclid orthokeratology lenses.

METHODS

The right eye data of myopic patients wearing Paragon CRT and Euclid orthokeratology in the ophthalmology department of The First Affiliated Hospital of Soochow University were retrospectively reviewed from April 2019 to October 2022. The TZD and ALG were compared between the Paragon CRT and Euclid groups. The correlation factors of TZD after wearing lens for 1 month and the relationship between the overlapping treatment zone-to-pupil area ratio and the ALG after wearing lens for 1 year were analyzed between the two groups.

RESULTS

There were 160 patients (160 eyes) in the Paragon CRT group and 155 patients (155 eyes) in the Euclid group. After wearing lens for 1 month, the TZD in the Paragon CRT group (3.72±0.37 mm) was larger than that in the Euclid group (3.26±0.37 mm) ( P <0.001). The stepwise multivariate linear regression analysis showed that the eccentricity at the flattest meridians (Em) and the central corneal thickness were correlated with the TZD in both groups ( P <0.05). After wearing lens for 1 year, the ALG in the Paragon CRT group (0.32±0.20 mm) was larger than that in the Euclid group (0.25±0.20 mm) ( P =0.001). The stepwise multivariate linear regression analysis showed that the initial wearing age and the overlapping treatment zone area-to-pupil area ratio were correlated with the ALG in both groups ( P <0.05).

CONCLUSION

For both the Paragon CRT and Euclid orthokeratology, the wearers with thicker central corneal thickness and smaller Em usually had a smaller TZD. In both groups, the overlapping treatment zone area-to-pupil area ratio was correlated with the ALG.

Efficacy of small back optic zone design on myopia control for corneal refractive therapy (CRT): a one-year prospective cohort study

BACKGROUND

To investigate the control effect on the axial length elongation using corneal refractive therapy (CRT) with different optical zone diameters (BOZDs). We also sought to compare the difference in higher-order aberrations (HOAs), treatment zone (TZ) size and Zernike defocus coefficient with different BOZDs and seek the optimal parameter for predicting axial elongation.

METHODS

This prospective cohort study included 7- to 14-year-olds fitted with orthokeratology (ortho-K) lenses of 5-mm (5-mm group) or 6-mm BOZD (6-mm group). Axial length (AL), corneal topography, HOAs and Zernike defocus coefficient were obtained at baseline, and 1, 3, 6, 9 and 12 months follow-up visits. Multivariate regression analyses were used to explore the association between AL change and ocular biometric parameters. Receiver operating characteristic (ROC) curve analysis was used to determine the best diagnostic value for AL change in ocular biometric parameters.

RESULTS

In total, 301 participants completed the one-year follow-up. The mean AL change in the 5-mm group (0.13 ± 0.18 mm) was less than that in the 6-mm group (0.27 ± 0.15 mm) at the 12 months visit. The TZ size and decentration were smaller, while the Zernike defocus coefficient and HOAs were higher in the 5-mm group (all P < 0.05). Older age and smaller TZ size were protective factors against AL elongation in multiple regression. In predicting AL elongation, TZ diameter yielded an area under the ROC curve of 0.684 with a cut-off value of 3.82 mm.

CONCLUSION

The 5-mm group showed 0.14 mm (51.8%) less axial elongation than the 6-mm group. The 5-mm BOZD produced a smaller TZ size, higher Zernike defocus coefficient and higher HOA after reshaping of the cornea. TZ size was the best predictor of AL elongation. TZ diameter less than 3.82 mm may lead to AL elongation less than 0.2 mm in one year.

Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study: A 2-year randomised clinical trial

PURPOSE

To compare axial elongation (AE) and treatment zone (TZ) characteristics in children wearing 6 mm or 5 mm back optic zone diameter (BOZD) orthokeratology (ortho-k) lenses over 2 years.

METHODS

Forty-five (6 to <11 years of age) myopic (-4.00 to -0.75 D) children of Chinese ethnicity were randomly assigned to use the two different lens designs (23 and 22 wore the 6 and 5 mm lenses, respectively). Data collection was performed at baseline and every 6-months after commencing lens wear.

RESULTS

After 24 months, subjects wearing lenses with a 5 mm BOZD achieved smaller TZ diameter (horizontal: 2.69 ± 0.28 vs. 3.84 ± 0.39 mm; vertical: 2.65 ± 0.22 vs. 3.42 ± 0.34 mm, p < 0.001) and less AE (0.15 ± 0.21 vs. 0.35 ± 0.23, p = 0.005) compared to those using the 6 mm design, with no difference in choroidal thickness (ChT) changes (p = 0.93). A significant increase in ChT, using pooled data analysis, was noted at the 6-month (11.8 ± 19.77 μm, p < 0.001) and 12-month (12.0 ± 23.7 μm, p = 0.004) visits, compared to baseline, indicating a transient change in ChT. Significant associations were noted, using linear mixed models, between AE and the TZ diameters (p < 0.003) after adjusting for baseline data. A very weak association was found between ChT changes and AE, with the effect size close to zero.

CONCLUSIONS

Smaller BOZD ortho-k lenses resulted in a smaller TZ diameter, which was associated with less AE after 2 years of treatment. The changes in ChT played a very weak role, suggesting that other factors may contribute more to the reduced AE in subjects wearing lenses having a smaller BOZD.

One-year results for myopia control with aspheric base curve orthokeratology lenses: A prospective randomised clinical trial

PURPOSE

To compare the effect of orthokeratology (ortho-k) using aspheric or spherical base curve (BCA vs. BCS) contact lenses on axial elongation and the relative peripheral refraction change (RPRC) in Chinese children.

METHODS

Children aged 8-12 years with myopia between -0.75 and -4.00 D and astigmatism ≤1.00 D were randomly assigned to the BCA or BCS group. Peripheral refraction was assessed at 10°, 20° and 30° along the temporal and nasal retina at baseline and at the 12-month visit. Axial length (AL) was measured under cycloplegia at baseline and at the 6- and 12-month visits. Only right eye data were analysed. Repeated-measures analysis of covariance was performed to examine the differences in axial elongation and the RPRC between the BCA and BCS groups.

RESULTS

The 1-year results from 31 BCA and 32 BCS subjects were analysed. No significant between-group differences were found at baseline (p ≥ 0.28). At the 12-month visit, the BCA lens produced a greater absolute RPRC along the horizontal meridian than the BCS lens (p < 0.001). Axial elongation was slower in the BCA group (0.19 ± 0.20 mm) than in the BCS group (0.29 ± 0.14 mm; p = 0.03). Axial elongation was correlated with the RPRC at 10° (r = 0.43, p = 0.02) and 20° (r = 0.39, p = 0.03) along the temporal retina in the BCA group; however, these correlations were not observed in the BCS group.

CONCLUSION

The BCA ortho-k lens could improve the efficacy of slowing axial elongation in children. The improved myopia control observed in the BCA group may be the result of a larger myopic shift in relative peripheral refraction within 20° along the temporal retina.

Comparison of two different orthokeratology lenses and defocus incorporated soft contact (DISC) lens in controlling myopia progression

BACKGROUND

To compare axial elongation in 8-11-year-old myopes wearing orthokeratology (OK) lenses with different back optic zone diameters (BOZD), defocus incorporated soft contact (DISC) lenses, and single-vision soft contact lenses (SCLs).

METHODS

A total of 122 children (aged 8-11 years) with spherical equivalent refraction (SER) between - 1.00 D and - 4.00 D were enrolled in this prospective study and randomly assigned to four groups: 5.0 mm-BOZD OK, 6.2 mm-BOZD OK, DISC, and single-vision SCLs. Children in each group were further divided into subgroups stratified by the average baseline SER: low myopic eyes (SER: - 1.00 D to - 2.50 D) and moderate myopic eyes (SER: - 2.50 D and over). Axial length (AL) was measured at baseline and after one year.

RESULTS

The 5.0 mm-BOZD OK, 6.2 mm-BOZD OK, and DISC groups exhibited significantly slower AL elongation than the SCL group. The proportion of slow progressors (AL elongation ≤ 0.18 mm/year) in the first three groups was 42%, 23%, and 29%, respectively. Furthermore, one-year AL elongation was significantly smaller in the 5.0 mm-BOZD OK group compared with the 6.2 mm-BOZD OK group. Regardless of SER, children in the 5.0 mm-BOZD OK and DISC groups showed comparably slower AL elongation than those in the SCL group. However, fitting with 6.2 mm-BOZD OK lenses significantly retarded AL elongation in moderate myopic eyes, but not in low myopic eyes.

CONCLUSIONS

Overall, 5.0 mm-BOZD OK lenses, 6.2 mm-BOZD OK lenses, and DISC lenses were effective in retarding AL elongation in 8-11-year-old myopes compared with single-vision SCLs, but for children with SER less than - 2.50 D, fitting with 5.0 mm-BOZD OK lenses and DISC lenses yielded better myopia control efficacy compared to wearing single-vision SCLs or 6.2 mm-BOZD OK lenses.

Characteristics of corneal microcysts in Hong Kong children wearing orthokeratology

PURPOSE

To report the characteristics (prevalence, severity, and location) of corneal epithelial microcysts and investigate associated risk factors in children wearing orthokeratology (ortho-k) lenses.

METHOD

Ninety-five myopic children wearing ortho-k lenses (examined by one of three independent investigators from March to September 2020) were included in this retrospective cross-sectional study. Pertinent data at baseline before ortho-k treatment and at the aftercare visits (the first visit when the microcysts were observed for children with microcysts, and the last visit before October 2020 for children without microcysts) were retrieved and analysed.

RESULTS

A microcystic response was observed in 52.6% of children wearing ortho-k lenses. Children with high myopia (≥ 5.00 D) had a higher prevalence (100.0%, 23/23) and severity (69.5% (16/23) > grade 2 Efron scale) compared to children with low myopia (≤ 4.00 D) (prevalence of 37.5% (27/72) and 7.0% (5/72) > grade 2, p < 0.001). Microcysts were predominantly (86.0%) observed in the region of the inferior pigmented arc, typically originating in the inferior mid-peripheral cornea, and expanding over time into a semi- or whole annulus. Baseline myopia and topographical change at the treatment zone centre were significantly greater (p < 0.05) in low myopic children with microcysts (univariate analyses).

CONCLUSIONS

During the COVID-19 pandemic, probably due to lifestyle changes, microcysts were frequently observed in children wearing ortho-k lenses and were associated with higher baseline myopia. Practitioners should examine ortho-k wearers with caution using a slit lamp with high magnification and illumination, especially the mid-peripheral cornea. The use of highly oxygen permeable lenses and frequent aftercare are necessary for ortho-k wearers, especially those with higher myopia.

Retrospective Analysis of Axial Length Changes in Overnight Orthokeratology in an Academic Myopia Control Clinic

SIGNIFICANCE

Although the myopia control efficacy of orthokeratology lenses has been established with clinical trials, reports of axial length change in non-study-based patient care are scarce. This study investigates the use of orthokeratology lenses for myopia control in a clinical population and compares axial elongation against those published in recent clinical investigations.

PURPOSE

This study aimed to investigate factors affecting axial elongation during use of orthokeratology lenses for myopia control in an academic clinical setting.

METHODS

This study was a retrospective consecutive case series from the Myopia Control Clinic at the Herbert Wertheim School of Optometry at the University of California, Berkeley (Berkeley, CA). Patients ranging from 5 to 18 years old using orthokeratology for at least 1 year were included in the study. Data from 102 patients' eyes were analyzed at baseline (before the initiation of treatment) and after 1 year of wear (12 ± 3 months). Multivariate analysis was undertaken to identify factors significantly associated with axial elongation over this period.

RESULTS

Mean (±standard deviation) spherical equivalent refraction and axial length at baseline were -2.54 (±1.21) D and 24.53 (±0.82) mm, respectively. By the 1-year follow-up, eyes had shown significant axial elongation (0.18 ± 0.24 mm; P < .001), which was found to be inversely correlated with age ( P < .001). Race, sex, baseline axial length, and baseline refraction were not significantly associated with axial elongation.

CONCLUSIONS

Factors influencing axial length and the magnitude of axial elongation in our orthokeratology patient population are consistent with orthokeratology treatment groups from published randomized clinical trials and support the use of these lenses for myopia control in a clinical practice setting.

Advances in myopia prevention strategies for school-aged children: a comprehensive review

Myopia has significantly risen in East and Southeast Asia, and the pathological outcomes of this condition, such as myopic maculopathy and optic neuropathy linked to high myopia, have emerged as leading causes of irreversible vision loss. Addressing this issue requires strategies to reduce myopia prevalence and prevent progression to high myopia. Encouraging outdoor activities for schoolchildren and reducing near-work and screen time can effectively prevent myopia development, offering a safe intervention that promotes healthier habits. Several clinical approaches can be employed to decelerate myopia progression, such as administering low-dose atropine eye drops (0.05%), utilizing orthokeratology lenses, implementing soft contact lenses equipped with myopia control features, and incorporating spectacle lenses with aspherical lenslets. When choosing an appropriate strategy, factors such as age, ethnicity, and the rate of myopia progression should be considered. However, some treatments may encounter obstacles such as adverse side effects, high costs, complex procedures, or limited effectiveness. Presently, low-dose atropine (0.05%), soft contact lenses with myopia control features, and orthokeratology lenses appear as promising options for managing myopia. The measures mentioned above are not necessarily mutually exclusive, and researchers are increasingly exploring their combined effects. By advocating for a personalized approach based on individual risk factors and the unique needs of each child, this review aims to contribute to the development of targeted and effective myopia prevention strategies, thereby minimizing the impact of myopia and its related complications among school-aged children in affected regions.

High myopia control is comparable between multifocal rigid gas-permeable lenses and spectacles

Purpose

Ocular pathology may be reduced by slowing myopia progression. The purpose of this study was to evaluate the potential of a novel custom-designed rigid gas permeable (RGP) contact lens to control high myopia by comparing the efficacy of multifocal RGP lenses and single-vision spectacles for high myopia control.

Methods

The medical records of children fitted with spectacles or multifocal rigid gas-permeable lenses between January 2018 and May 2020 were retrospectively reviewed. Children (5-17 years) with non-cycloplegic spherical equivalent refraction of ≤ -6.00 D or spherical equivalent refraction > - 6.00 D with baseline axial length ≥ 26.5 mm, and astigmatism of ≥ -2.00 D were included. Axial length and refraction were measured at baseline, before fitting the participants with multifocal rigid gas-permeable lenses or spectacles, and at 1- and 2-year follow-up visits. Changes in axial length were compared between the groups.

Results

Among the 77 children with 1-year follow-up data, the mean axial elongation was 0.20 ± 0.17 mm and 0.21 ± 0.14 mm in the multifocal rigid gas-permeable and control groups, respectively, without significant differences between groups (F = 0.004, p = 0.835). Among the 41 patients who completed 2 years of follow-up, the mean axial elongation values in the multifocal rigid gas-permeable and control groups were 0.21 ± 0.15 mm and 0.24 ± 0.13 mm, respectively, at the 1-year follow-up, and 0.37 ± 0.27 mm and 0.43 ± 0.23 mm, respectively, at the 2-year follow-up, without significant between-group differences at either time point (p = 0.224).

Conclusion

Axial length increased at a similar rate in both the control (spectacles) and multifocal rigid gas-permeable lens groups, suggesting that multifocal rigid gas-permeable lenses have no significant impact on controlling high myopia progression compared with spectacles.

Factors influencing treatment zone size in orthokeratology

PURPOSE

The aim of this study was to analyze the influence of corneal topography, contact lens parameters and degree of myopia on the treatment zone (TZ) and peripheral plus ring (PPR) size in orthokeratology.

METHODS

In this retrospective study the topographic zones of the right eyes of 106 patients (73 female, 22.16 ± 8.96 years) were analyzed in the tangential difference map of the Oculus Keratograph 5M (Oculus, Wetzlar, Germany). Using the MB-Ruler Pro 5.4 software (MB-Softwaresolutions, Iffezheim, Germany) the horizontal, vertical, longest, shortest diameters and area of the TZ; horizontal, vertical, total diameters and width of the PPR were measured. Correlations were determined between these zones and the subjects' baseline parameters (myopia; corneal diameter, radii, astigmatism, eccentricity, sagittal height; contact lens radii, toricity and total diameter) for three back optic zone diameter (BOZD) groups (5.5, 6.0 and 6.6 mm). A stepwise linear regression analysis was performed to test for TZ and PPR predictability.

RESULTS

In the group of BOZD 6.0 correlations were found between the amount of myopia and the short TZ diameter (r = -0.25, p = 0.025); the steep corneal radius and the vertical diameter (r = -0.244, p = 0.029), the longest diameter (r = -0.254, p = 0.023) and the area (r = -0.228, p = 0.042) of the TZ; the amount of astigmatism and PPR width (r = 0.266, p = 0.017); eccentricity of the steep corneal meridian and PPR width (r = -0.222, p = 0.047). BOZD correlated significantly positively with all zones (p < 0.05). The best prediction model (R2 = 0.389) resulted with the TZ area as the outcome variable.

CONCLUSION

The amount of myopia, topography and contact lens parameters influence TZ and PPR in orthokeratology. Describing the TZ by its area may provide the most accurate representation of its size.

Long-term variations and influential factors of the treatment zone of wearing orthokeratology lenses

PURPOSE

To investigate the variation trend of the treatment zone (TZ) during 12 months of Orthokeratology (Ortho-K) from the perspective of the treatment zone size (TZS), decentration (TZD) and the weighted Zernike defocus coefficient of the treatment zone (Cweighteddefocus).

METHODS

94 patients were included in this retrospective study, who were fitted with a 5-curve vision shaping treatment (VST) lens (n = 44) or a 3-zone corneal refractive therapy (CRT) lens (n = 50). The TZS, TZD and Cweighteddefocus up to 12 months were analyzed.

RESULTS

TZS (F(4,372) = 10.167, P＜0.001), TZD (F(4,372) = 8.083, P＜0.001) and Cweighteddefocus (F(4,372) = 7.100, P＜0.001) were significantly increased with time during overnight Ortho-K treatment. The TZS increased sharply from 1 week to 1 month of overnight Ortho-K (F = 25.479, P <.001) and stayed smooth then. It showed growing tendency from 6 to 12 months (F = 8.407, P =.005). The TZD (F = 16.637, P <.001) and Cweighteddefocus (F = 13.401, P <.001) increased significantly until 1 month and kept stable until 12 months (all P＞0.05). The univariant linear regression analysis showed that TZS of the last visit was correlated with baseline myopia (β = 0.219, P =.034). Also, the greater final Cweighteddefocus was correlated with higher baseline myopia (β = -0.589, P＜0.001) and higher corneal astigmatism (β = -0.228, P =.007) at the onset of lens wear with the multiple linear regression.

CONCLUSION

The TZS, TZD and Cweighteddefocus kept stable after 1 month of Ortho-K while the TZS had an increasing trend after 6 months. Children with higher myopic eyes or higher corneal astigmatism at baseline tended to have smaller TZS and greater Cweighteddefocus at 12 months.

Optical changes and association with axial elongation in children wearing orthokeratology lenses of different back optic zone diameter

PURPOSE

To compare changes in ocular aberrations in children wearing orthokeratology (ortho-k) lenses with a back optic zone diameter (BOZD) of 6 mm (6-MM group) or 5 mm (5-MM group) and their associations with axial elongation (AE) over two years.

METHODS

Seventy Chinese children, aged 6 to < 11 years, with myopia between - 4.00 to - 0.75 D, were randomly allocated to 5-MM and 6-MM groups. Ocular aberrations were measured, rescaled to a 4-mm pupil, and fitted with a 6th order Zernike expansion. Measurements, including axial length, were taken prior to commencing ortho-k treatment and then every six months over two years.

RESULTS

After two years, the 5-MM group displayed a smaller horizontal treatment zone (TZ) diameter (by 1.14 ± 0.11 mm, P < 0.001) and less AE (by 0.22 ± 0.07 mm, P = 0.002) compared with the 6-MM group. A greater increase in total root mean square (RMS) of higher-order aberrations (HOAs), primary spherical aberration (SA) ([Formula: see text], and coma were also observed in the 5-MM group at all follow-up visits. The horizontal TZ diameter was significantly associated with changes in RMS HOAs, SA (RMS, primary and secondary SA), and RMS coma. After controlling for baseline parameters, RMS HOAs, RMS SA, RMS coma, and primary ([Formula: see text] and secondary ([Formula: see text] SA were significantly associated with AE.

CONCLUSIONS

Ortho-k lenses with a smaller BOZD created a smaller horizontal TZ diameter and a significant increase in total HOAs, total SA, total coma, and primary SA and a decrease in secondary SA. Of these ocular aberrations, total HOAs, total SA, and primary SA were negatively correlated with AE over two years.

TRIAL REGISTRATION

ClinicalTrial.gov, NCT03191942. Registered 19 June 2017, https://clinicaltrials.gov/ct2/show/NCT03191942 .

Interventions for myopia control in children: a living systematic review and network meta-analysis

BACKGROUND

Myopia is a common refractive error, where elongation of the eyeball causes distant objects to appear blurred. The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Since myopia is usually detected in children before 10 years of age and can progress rapidly, interventions to slow its progression need to be delivered in childhood.

OBJECTIVES

To assess the comparative efficacy of optical, pharmacological and environmental interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of myopia control interventions according to their efficacy. To produce a brief economic commentary, summarising the economic evaluations assessing myopia control interventions in children. To maintain the currency of the evidence using a living systematic review approach.  SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE; Embase; and three trials registers. The search date was 26 February 2022.  SELECTION CRITERIA: We included randomised controlled trials (RCTs) of optical, pharmacological and environmental interventions for slowing myopia progression in children aged 18 years or younger. Critical outcomes were progression of myopia (defined as the difference in the change in spherical equivalent refraction (SER, dioptres (D)) and axial length (mm) in the intervention and control groups at one year or longer) and difference in the change in SER and axial length following cessation of treatment ('rebound').  DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methods. We assessed bias using RoB 2 for parallel RCTs. We rated the certainty of evidence using the GRADE approach for the outcomes: change in SER and axial length at one and two years. Most comparisons were with inactive controls.

MAIN RESULTS

We included 64 studies that randomised 11,617 children, aged 4 to 18 years. Studies were mostly conducted in China or other Asian countries (39 studies, 60.9%) and North America (13 studies, 20.3%). Fifty-seven studies (89%) compared myopia control interventions (multifocal spectacles, peripheral plus spectacles (PPSL), undercorrected single vision spectacles (SVLs), multifocal soft contact lenses (MFSCL), orthokeratology, rigid gas-permeable contact lenses (RGP); or pharmacological interventions (including high- (HDA), moderate- (MDA) and low-dose (LDA) atropine, pirenzipine or 7-methylxanthine) against an inactive control. Study duration was 12 to 36 months. The overall certainty of the evidence ranged from very low to moderate. Since the networks in the NMA were poorly connected, most estimates versus control were as, or more, imprecise than the corresponding direct estimates. Consequently, we mostly report estimates based on direct (pairwise) comparisons below. At one year, in 38 studies (6525 participants analysed), the median change in SER for controls was -0.65 D. The following interventions may reduce SER progression compared to controls: HDA (mean difference (MD) 0.90 D, 95% confidence interval (CI) 0.62 to 1.18), MDA (MD 0.65 D, 95% CI 0.27 to 1.03), LDA (MD 0.38 D, 95% CI 0.10 to 0.66), pirenzipine (MD 0.32 D, 95% CI 0.15 to 0.49), MFSCL (MD 0.26 D, 95% CI 0.17 to 0.35), PPSLs (MD 0.51 D, 95% CI 0.19 to 0.82), and multifocal spectacles (MD 0.14 D, 95% CI 0.08 to 0.21). By contrast, there was little or no evidence that RGP (MD 0.02 D, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.07 D, 95% CI -0.09 to 0.24) or undercorrected SVLs (MD -0.15 D, 95% CI -0.29 to 0.00) reduce progression.  At two years, in 26 studies (4949 participants), the median change in SER for controls was -1.02 D. The following interventions may reduce SER progression compared to controls: HDA (MD 1.26 D, 95% CI 1.17 to 1.36), MDA (MD 0.45 D, 95% CI 0.08 to 0.83), LDA (MD 0.24 D, 95% CI 0.17 to 0.31), pirenzipine (MD 0.41 D, 95% CI 0.13 to 0.69), MFSCL (MD 0.30 D, 95% CI 0.19 to 0.41), and multifocal spectacles  (MD 0.19 D, 95% CI 0.08 to 0.30). PPSLs (MD 0.34 D, 95% CI -0.08 to 0.76) may also reduce progression, but the results were inconsistent. For RGP, one study found a benefit and another found no difference with control. We found no difference in SER change for undercorrected SVLs (MD 0.02 D, 95% CI -0.05 to 0.09). At one year, in 36 studies (6263 participants), the median change in axial length for controls was 0.31 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.33 mm, 95% CI -0.35 to 0.30), MDA (MD -0.28 mm, 95% CI -0.38 to -0.17), LDA (MD -0.13 mm, 95% CI -0.21 to -0.05), orthokeratology (MD -0.19 mm, 95% CI -0.23 to -0.15), MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09), pirenzipine (MD -0.10 mm, 95% CI -0.18 to -0.02), PPSLs (MD -0.13 mm, 95% CI -0.24 to -0.03), and multifocal spectacles (MD -0.06 mm, 95% CI -0.09 to -0.04). We found little or no evidence that RGP (MD 0.02 mm, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.03 mm, 95% CI -0.10 to 0.03) or undercorrected SVLs (MD 0.05 mm, 95% CI -0.01 to 0.11) reduce axial length. At two years, in 21 studies (4169 participants), the median change in axial length for controls was 0.56 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.47mm, 95% CI -0.61 to -0.34), MDA (MD -0.33 mm, 95% CI -0.46 to -0.20), orthokeratology (MD -0.28 mm, (95% CI -0.38 to -0.19), LDA (MD -0.16 mm, 95% CI -0.20 to  -0.12), MFSCL (MD -0.15 mm, 95% CI -0.19 to -0.12), and multifocal spectacles (MD -0.07 mm, 95% CI -0.12 to -0.03). PPSL may reduce progression (MD -0.20 mm, 95% CI -0.45 to 0.05) but results were inconsistent. We found little or no evidence that undercorrected SVLs (MD -0.01 mm, 95% CI -0.06 to 0.03) or RGP (MD 0.03 mm, 95% CI -0.05 to 0.12) reduce axial length. There was inconclusive evidence on whether treatment cessation increases myopia progression. Adverse events and treatment adherence were not consistently reported, and only one study reported quality of life. No studies reported environmental interventions reporting progression in children with myopia, and no economic evaluations assessed interventions for myopia control in children.

AUTHORS' CONCLUSIONS

Studies mostly compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. Effects at one year provided evidence that these interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. A smaller body of evidence is available at two or three years, and uncertainty remains about the sustained effect of these interventions. Longer-term and better-quality studies comparing myopia control interventions used alone or in combination are needed, and improved methods for monitoring and reporting adverse effects.

Long-term follow-up of changes in ocular biometric parameters in orthokeratology lens wearers with relatively large-scale axial length reduction

BACKGROUND

To investigate ocular biological characteristics for myopic children with axial length (AL) reduction during orthokeratology (Ortho-K) treatment and provide clinical clues for better myopia control effects.

METHODS

Changes in ocular parameters and treatment zone (TZ) in 75 subjects who completed one-year Ortho-K treatment were retrospectively reviewed. The subjects were divided into two groups according to one-year AL change: the AL reduction group (n = 37) and the AL elongation group (n = 38). Univariate and multivariate regression analyses were performed to determine the association between TZ, ocular parameters, and AL change.

RESULTS

There was no significant difference in baseline between the two groups (all P > 0.05). After one year of Ortho-K treatment, compared with those in the AL elongation group, children in the AL reduction group had a decreased anterior chamber depth (ACD) (P < 0.001), thickened crystalline lens thickness (CLT) (P = 0.002), thinned vitreous chamber depth (VCD) (P < 0.001) and smaller TZ (P = 0.03), but no difference in central corneal thickness (CCT) and pupil diameter (PD). In the multivariable analyses, AL reduction was negatively associated with baseline age (beta: - 0.048; 95% CI: - 0.083 to - 0.013; P = 0.009) and positively associated with the TZ (beta: 0.024; 95% CI: 0.009 to 0.040; P = 0.003).

CONCLUSIONS

In AL reduction eyes, thickened CLT, decreased ACD and thinned VCD were observed during Ortho-K treatment, which could be suggested as indicators for better myopia control effects in the clinic. Older baseline age and smaller TZ wearing Ortho-K were also associated with AL change. Thickened CLT may be a result of compensation for AL-reduction eyes.

Ocular signs and symptoms of orthokeratology patients associated with povidone iodine-based disinfecting solution

PURPOSE

To determine the frequency and severity of ocular symptoms and signs in new orthokeratology (ortho-k) subjects using a povidone iodine (PI) disinfecting system compared to those present before lens wear, and whether these were associated with cleaning regimes.

METHODS

This study recruited 80 subjects from two myopia control studies, who used a PI disinfecting solution for routine use. Ocular symptoms and signs at baseline, one- and six-month after lens wear were reported via questionnaires and ocular examination, respectively. To determine if rates of occurrence were attributable to differences in cleaning regime, subjects were randomly assigned into four groups with respect to routine care procedures, which involved various combinations of rubbing and use of a daily and/or enzymatic cleaner.

RESULTS

Sixty-eight subjects completed all aspects of the study. As there were no significant differences in incidence of signs and symptoms between the four groups before and after lens wear (Friedman tests, p > 0.07), data were combined for further analysis. Prior to lens wear, itchiness (69 %) and dryness (53 %) were the most commonly reported symptoms. The frequency and severity of all symptoms remained similar after lens wear (p > 0.10). Presence of follicles in the lower tarsal conjunctiva (22 %) and conjunctival injection (15 %) was frequently observed, but reduced significantly after lens wear (p < 0.01). Mild corneal staining, noted in 13 % of subjects at baseline, did not change significantly over time (p = 0.17). Ocular signs were not necessarily reflected in symptoms and vice versa.

CONCLUSION

Use of a PI-based solution did not increase the frequency or severity of ocular signs and symptoms observed before lens wear. Absence of a difference in occurrence of ocular discomfort with respect to cleaning regimes indicated that the use of the PI-based solution may adequately clean the lenses over a 6-month period.

Biometric factors and orthokeratology lens parameters can influence the treatment zone diameter on corneal topography in Corneal Refractive Therapy lens wearers

PURPOSE

To investigate the relationship between patients' baseline biometric factors or lens parameters and the diameter of the treatment zone in young myopic children undergoing Corneal Refractive Therapy.

METHODS

The data of patients undergoing Corneal Refractive Therapy lens treatment within two years were retrospectively reviewed. Baseline clinical data, including sex, age, refractive power, corneal topography readings, ocular optical biometric measurements, and Corneal Refractive Therapy lens parameters, were subjected to Pearson, Spearman, and partial correlation analyses to identify the potential factors that may influence treatment zone diameter on corneal topography. Logistic and linear regression analyses were used to predict the treatment zone size.

RESULTS

The Right eyes of 309 patients were included in this study. The spherical refraction, flat keratometric reading, Reverse Zone Depth 2, Landing Zone Angle 1, and lens diameter were independent factors of treatment zone diameter. In the multivariate analyses, Landing Zone Angle 1 was positively correlated, while Reverse Zone Depth 2 and lens diameter were negatively correlated with the size of the treatment area. The accuracy of logistic regression in predicting the treatment zone size was 71.5%.

CONCLUSION

Adjustments to Corneal Refractive Therapy lens parameters may influence the treatment zone diameter on corneal topography. A higher Reverse Zone Depth 2, smaller Landing Zone Angle 1, and larger lens diameter can lead to a smaller treatment zone for Corneal Refractive Therapy lens treatment.

Orthokeratology lenses with increased compression factor (OKIC): A 2-year longitudinal clinical trial for myopia control

PURPOSE

To investigate the effectiveness of orthokeratology (ortho-k) lenses and corneal changes with increased compression factor for myopia control over a 2-year period.

METHODS

Young participants (age: 6-<12 years), with low myopia (0.50-4.00 D) and low astigmatism (≤1.25 D), were recruited and allowed to choose to wear either single-vision spectacles or ortho-k lenses (randomly assigned to compression factor of either 0.75 or 1.75 D). Axial length and cycloplegic refraction were measured at six monthly intervals for two years by a masked examiner. The myopia control effectiveness was determined by axial elongation.

RESULTS

A significant number of control (63 %) dropped out, mainly due to concern about myopia progression (58 %). A total of 75 participants (mean age: 9.3 ± 1.0 years; control: n = 11, ortho-k [0.75 D]: n = 29, ortho-k [1.75 D]: n = 35) completed the study. Considering ortho-k groups only, the mean axial elongation of participants wearing ortho-k lenses of conventional compression factor (0.75 D) and increased compression factor (1.75 D) were 0.53 ± 0.29 and 0.35 ± 0.29 mm, respectively, over the 2-year study period. The between-group differences in corneal health were not significant at all visits.

CONCLUSION

Participants wearing ortho-k lenses of increased compression factor further slowed axial elongation by 34%, when compared with the conventional compression factor without compromising corneal health. Further investigations are warranted to confirm the potential mechanism of an increased compression factor for improved myopia control effectiveness.

The effect of corneal power distribution on axial elongation in children using three different orthokeratology lens designs

PURPOSE

To investigate the correlation between spatial corneal power distribution and one-year axial length (AL) elongation using three ortho-k lens designs by a unified mathematical method.

METHODS

A total of 137 subjects were included: 42 with Euclid lenses, 28 with DRL lenses, and 67 with CRT lenses. AL elongation, Xmax, Ymax and power exponent were compared among the three groups. One-year relative corneal refractive power change (RCRPC) was calculated by a polynomial function and a monomial function. Factors including age, baseline spherical equivalent refractive error (SER), Xmax, Ymax and power exponent was tested against one-year AL growth in a stepwise multiple linear regression model.

RESULTS

The power exponent (F = 7.29, P = 0.0012) and Xmax (F = 62.88, P < 0.0001) of the DRL group was significantly smaller than that of the other two lens groups. Ymax was not significantly different among three lens groups (F = 1.18, P = 0.31). The one-year AL elongation of the DRL group (0.09 ± 0.14 mm) was significantly slower than that of the Euclid group (0.26 ± 0.14 mm, P = 0.002) and CRT group (0.32 ± 0.18 mm, P < 0.0001). AL elongation was significantly correlated with Xmax (standardized β = 0.196, P = 0.003), power exponent (standardized β = 0.644, P < 0.001), and age (standardized β = -0.263, P < 0.001), with R² being 0.608.

CONCLUSION

A smaller and more aspheric treatment zone may be beneficial for reducing axial elongation in children undergoing ortho-k treatment, regardless of their baseline myopic refractive error.

The effect of back optic zone diameter on relative corneal refractive power distribution and corneal higher-order aberrations in orthokeratology

PURPOSE

To compare axial elongation, relative corneal refractive power (RCRP) distribution within the pupillary diameter, and corneal higher-order aberrations (HOAs) in myopic children wearing orthokeratology (ortho-k) lenses with different back optic zone diameters (BOZD).

METHODS

Children aged 8-11 years were fitted with 5.0 or 6.2 mm-BOZD ortho-k lenses (groups A and B, respectively). Axial length (AL) and corneal topography were measured at baseline and during the annual visit. RCRP and corneal HOAs were compared between the two groups after one-year treatment. Multivariate linear regression analysis was performed to determine the association between AL elongation and RCRP parameters, corneal HOAs, and other variables between the groups.

RESULTS

After one-year treatment, axial elongation was slower in group A than in group B, with a difference of 0.15 mm. Children in group A showed smaller treatment zone size, smaller 3/4X value (describing the distance from the apex RCRP profile rising to its three-quarter-peak level), greater RCRP sum value within the pupillary area, and higher increases in corneal total HOAs and horizontal coma (Z₃¹). AL elongation was significantly correlated with baseline age, baseline spherical equivalent refraction (SER), treatment zone size, and 3/4X value.

CONCLUSIONS

Ortho-k lenses designed with smaller BOZD increased myopia control efficacy, induced a steeper distribution of the RCRP profile within the pupillary diameter, and induced greater increases in corneal total HOAs and horizontal coma (Z₃¹). Lens-induced RCRP profile within pupillary diameter, rising to its three-quarter-peak level at a smaller distance, may show a better myopia control effect.

The effects of base curve aspheric orthokeratology lenses on corneal topography and peripheral refraction: A randomized prospective trial

BACKGROUND

To investigate the effects of orthokeratology (ortho-k) lenses with aspheric and spherical base curve designs on corneal refractive power (CRP) and peripheral refraction.

METHODS

Children aged 8 to 12 years with myopia between -0.75 D to -4.00 D, astigmatism ≤1.00 D, and corneal astigmatism ≤1.50 D were randomly assigned to the base curve aspheric (BCA) and base curve spherical (BCS) ortho-k lens groups. CRP was assessed for the central 8 mm cornea along horizontal and vertical meridians, and peripheral refraction was measured at 10°, 20°, and 30° along the nasal and temporal retina. Primary measurements included relative corneal refractive power change (RCRPC) and relative peripheral refraction change (RPRC).

RESULTS

The 3-month results of the 33 and 29 subjects (right eye only) in the BCA and BCS groups, respectively, were obtained. Nonsignificant differences were found in the baseline data between the two groups (p > 0.05). At the 3-month follow-up visit, the mean RCRPC in the BCA group (2.08 ± 0.65 D) was significantly greater than that in the BCS group (1.32 ± 0.81 D) (F_1,51 = 25.25, p < 0.001). The BCA group (-1.82 ± 0.65 D) exhibited a larger absolute RPRC than the BCS group (-0.98 ± 0.54 D) (F_1,57 = 33.73, p < 0.001).

CONCLUSIONS

It was found that the BCA ortho-k lens resulted in a more aspheric treatment zone and a more myopic relative peripheral refraction (RPR) along the horizontal meridian. The more myopic RPR was contributed by a more hyperopic central refraction and a more myopic peripheral refraction in the BCA group.

[Changes in the wavefront and peripheral defocus profile after excimer laser and orthokeratology corneal reshaping in myopia]

PURPOSE

This study compares the trends of changes in corneal asphericity, corneal and total aberrations and peripheral refraction in myopic eyes after excimer laser and orthokeratology correction.

MATERIAL AND METHODS

Aberrometry (OPD-Scan III; Nidek, Japan) was performed in 63 patients (126 eyes) with moderate and high myopia before and after femtosecond laser-assisted in situ keratomileusis (Femto-LASIK; 88 eyes, group 1) and photorefractive keratectomy (PRK; 38 eyes, group 2). Peripheral refraction (Grand Seiko AutoRef/Keratometer) at 15° and 30° from the center of the fovea was observed in 12 patients of group 1 and in 18 patients with a background of orthokeratology correction (group 3).

RESULTS

Corneal asphericity factor Q transitioned to positive values after PRK and Femto-LASIK. Corneal aberrations: root mean square higher order aberration (RMS HOA) increased in both groups, Tilt 1 increased in group 1 and became negative in group 2, Tilt 2 increased in group 2 and went negative in group 1. Trefoil 6 did not change in group 1 and decreased in group 2. Coma 7 and 8 increased synchronously in both groups. Spherical aberrations (SA) increased in group 1, and went negative in group 2. Total aberrations changed to a lower degree, and these changes were not synchronous with the corneal ones; RMS HOA decreased in group 1 (while corneal RMS increased significantly), and in the PRK group it increased, but much less than the corneal. Total SA increased in group 1 and did not change in group 2. Peripheral myopic defocus formed in all cases, after Femto-LASIK the maximum was in the zone of 30º, after orthokeratology lenses - in the zone of 15º.

CONCLUSION

Using excimer laser and orthokeratology to reshape the cornea in full accordance with its different profiles have different effects on the wavefront and peripheral refraction of the eye. The internal optics of the eye partially compensates corneal aberrations induced by the excimer laser.

Weighted Zernike defocus coefficient of treatment zone is a meaningful indicator for myopia control efficacy of Ortho-K lenses

Background

The goal of this study was to reproduce a three-dimensional representation of corneal defocus characteristics after orthokeratology (Ortho-K) treatment via an indicator defined as the weighted Zernike defocus coefficient of the treatment zone (C_{weighted defocus}). This could be used to predict the effectiveness of Ortho-K treatment quantitatively in a timely manner after the one-month visit.

Methods

Seventy myopic children with axial length (AL) elongation after Ortho-K treatment (group A) and 63 myopic children with AL shortening after Ortho-K treatment (group B) were included in this one-year retrospective study. The proposed indicator was calculated by a customized MATLAB program. Multivariate binomial logistic regression and multivariate linear regression analyses were used to explore the association between AL change and the C_{weighted defocus}, age, sex, and other ocular biometric parameters.

Results

The 12-month AL change, age, pupil diameter, and vertical decentration of the Ortho-K lens were significantly different between the two groups. Multivariate logistic regression analysis showed that a larger C_{weighted defocus} (≥ 0.35 D/mm²) (OR: 0.224; 95% CI: 0.078–0.646; P = 0.006) was correlated with the emergence of AL shortening after orthokeratology treatment. A multivariate linear regression model showed that a greater C_{weighted defocus} was associated with slower 12-month AL elongation (β =  − 0.51, P = 0.001).

Conclusions

The C_{weighted defocus} is an effective predictive indicator of myopia control, and a larger C_{weighted defocus} may lead to slower elongation of AL. This meaningful indicator may help in the evaluation and adjustment of Ortho-K lens parameters in a timely manner and minimize the cost of clinical trial and error.

Axial length shortening after orthokeratology and its relationship with myopic control

Purpose

To determine the pattern of axial variation in subjects with initial shortened axial length during the entire period of orthokeratology and to discuss the possibility of shortened AL after one month of orthokeratology becoming a predictor of myopia control.

Method

This study retrospectively included 106 children with myopia aged 8 to 14 wearing OK lenses. Fifty-four eyes with shortened axial length (AL) at the first-month visit were enrolled in the axial length shortening (ALS) group, and fifty-two eyes without shortened AL were enrolled in the no axial length shortening (NALS) group. Axial length and refractive error at baseline and within the entire period of orthokeratology (20 months), including fitting, washout period and re-wear, were measured. Eighty-five children who started wearing single vision spectacle were also included as a control group.

Results

In the ALS group, AL became longer after shortening and slowly exceeded baseline; afterward, AL experienced a rebound during the washout period and shortened again if OK lenses were re-worn. After washout period, significant difference in AL (ALS:0.28 ± 0.19 mm, NALS: 0.52 ± 0.17 mm) and spherical equivalent (ALS:-0.43 ± 0.44D, NALS:-0.91 ± 0.40D) between the two groups were found(P<0.05). The changes in AL and SE were both significantly correlated with the changes in AL at the first-month visit (P<0.05).

Conclusion

After AL is shortened in the initial stage of orthokeratology, it will experience a rapid rebound during the washout period, and the shortening can reappear when re-wearing OK lenses. Hence, the evaluation of orthokeratology will be more objective and accurate after the wash-out period. In addition, the existence and degree of axial shortening can be used as a predictor of long-term myopia development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02461-4.

Treatment zone decentration promotes retinal reshaping in Chinese myopic children wearing orthokeratology lenses

PURPOSE

To investigate whether the treatment zone (TZ) decentration in orthokeratology (OK) lenses affects retinal expansion in Chinese children with myopia.

METHODS

Children aged 8 to 13 years (n = 30) were assessed over 13 months comprising 12 months of OK lens wear followed by discontinuation of lens wear for 1 month. Corneal topography was measured at 0, 1, 3, 6, 9, 12 and 13 months. TZ decentration of the OK lens was calculated, and subjects were subdivided into a small decentration group (group S) and a large decentration group (group L) based on the median value of the weighted average decentration (d_ave ). Central axial length (AL) and peripheral eye lengths (PELs) at the central retina, as well as 10°, 20° and 30° nasally and temporally were measured at 0 and 13 months under cycloplegia. Second-order polynomial (y = ax²  + bx + c) and linear fits (y = Kx + B) were applied to the peripheral relative eye length (PREL), and the coefficients 'a' and 'K' were used to describe the shape of the eye.

RESULTS

Mean AL growth for one year was 0.28 ± 0.17 mm. In a multiple linear regression model, AL elongation was related to the baseline age (β = -0.41, p = 0.01) and the d_ave (β = -0.37, p = 0.03) (R²  = 0.34, p = 0.002). When compared with smaller d_ave (0.45 ± 0.15 mm), a larger d_ave (0.89 ± 0.17 mm) was associated with slower ocular growth (central: 0.20 ± 0.13 mm vs. 0.35 ± 0.17 mm, p = 0.009; 10° nasal: 0.26 ± 0.18 mm vs. 0.45 ± 0.21 mm, p = 0.02; 10° temporal: 0.17 ± 0.14 mm vs. 0.32 ± 0.19 mm, p = 0.02) and more oblate retina shape ('a': -0.13 ± 0.02 vs. -0.14 ± 0.02, p = 0.02; K_nasal : 0.35 ± 0.11 vs. 0.39 ± 0.09, p = 0.02; K_temporal : -0.42 ± 0.08 vs. -0.46 ± 0.08, p = 0.004).

CONCLUSIONS

Greater TZ decentration with the use of OK lenses was associated with slower axial growth and a more oblate retinal shape. TZ decentration caused local defocusing changes, which may inhibit myopic progression. These findings may have important implications for improving optical designs for myopia control.