Factors associated with faster axial elongation after orthokeratology treatment

Effectiveness of orthokeratology and myopia control spectacles in a real-world setting in China

OBJECTIVE

To compare the effectiveness of myopia control in Chinese children, who had been wearing either orthokeratology (ortho-k) lenses or myopia control spectacles (MCS) for one year.

METHODS

Relevant data were retrieved from 212 patients, with baseline myopia of -5.00 to -0.75 D, astigmatism ≤ 1.50 D, who had been undergoing myopia control treatment with either ortho-k (Euclid (OK1) or CRT (OK2)) or MCS (Stellest (MCS1) or DIMS (MCS2)) for at least one year. Myopia control effectiveness among the four groups was compared based on the change in spherical equivalent refraction (SER) (for the spectacle groups) and axial length (AL) (for all groups). Data retrieved, from the right eye only, included best corrected visual acuity (BCVA), SER, and AL at both the initial clinic visit (baseline) and the one-year visit was analysed.

RESULTS

Although no significant differences in gender, cylindrical power, or BCVA were observed at the baseline visit (P > 0.05), there were significant differences in baseline age, myopia, and AL among the four groups (P < 0.05). No significant difference in axial elongation (AE) was found among the four groups after one year of treatment (P = 0.49). AE, adjusted for baseline age and spherical power, were 0.19 ± 0.15, 0.18 ± 0.14, 0.19 ± 0.19, 0.20 ± 0.18 mm for OK1, OK2, MCS1, MCS2, respectively. Only age was a significantly factor associated with AE and SER increase (P < 0.05), with negative associations between AE and age in all groups and positive association between SER increase and baseline age in the spectacle groups observed.

CONCLUSION

Both brands of ortho-k lenses and MCS had similar myopia control effectiveness for mild to moderate myopic children treated in a real-world setting in China. Average AE in one year ranged from 0.18 to 0.20 mm, comparable to previous reports on myopia control using ortho-k.

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.

A retrospective study of cumulative absolute reduction in axial length after photobiomodulation therapy

BACKGROUND

To assess the age and timeline distribution of ocular axial length shortening among myopic children treated with photobiomodulation therapy in the real world situations.

METHODS

Retrospective study of photobiomodulation therapy in Chinese children aged 4 to 13 years old where axial length measurements were recorded and assessed to determine effectiveness at two age groups (4 ∼ 8 years old group and 9 ∼ 13 years old group). Data was collected from myopic children who received photobiomodulation therapy for 6 ∼ 12 months. Effectiveness of myopia control was defined as any follow-up axial length ≤ baseline axial length, confirming a reduction in axial length. Independent t-test was used to compare the effectiveness of the younger group and the older group with SPSS 22.0.

RESULTS

342 myopic children were included with mean age 8.64 ± 2.20 years and baseline mean axial length of 24.41 ± 1.17 mm. There were 85.40%, 46.30%, 71.20% and 58.30% children with axial length shortening recorded at follow-up for 1 month, 3 months, 6 months and 12 months, respectively. With respect to the axial length shortened eyes, the mean axial length difference (standard deviation) was - 0.039 (0.11) mm, -0.032 (0.11) mm, -0.037 (0.12) mm, -0.028 (0.57) mm at 1, 3, 6, and 12-month follow-up, respectively. Greater AL shortening was observed among the older group who had longer baseline axial lengths than the younger group (P < 0.001).

CONCLUSIONS

Overall myopia control effectiveness using photobiomodulation therapy was shown to be age and time related, with the maximum absolute reduction in axial elongation being cumulative.

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.

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.

Long-Term Axial Length Shortening in Myopic Orthokeratology: Incident Probability, Time Course, and Influencing Factors

Purpose

Long-term axial length (AL) shortening in myopia is uncommon but noteworthy. Current understanding on the condition is limited due to difficulties in case collection. The study reported percentage, probability, and time course of long-term AL shortening in myopic orthokeratology based on a large database.

Methods

This study reviewed 142,091 medical records from 29,825 subjects in a single-hospital orthokeratology database that were collected over 10 years. Long-term AL shortening was defined as a change in AL of -0.1 mm or less at any follow-up beyond 1 year. Incident probability was calculated based on multivariate logistic regression. Time course was estimated using mixed-effect regression model.

Results

A total of 10,093 subjects (mean initial age, 11.70 ± 2.52 years; 58.8% female) with 80,778 visits were included. The number of subjects experienced long-term AL shortening was 1,662 (16.47%; 95% confidence interval, 15.75%-17.21%). Initial age showed significant impact on the incident occurrence (OR, 1.37; 95% confidence interval, 1.34-1.40; P < 0.001). The estimated probability of AL shortening was approximately 2% for subjects with initial age of 6 years and 50% for those aged 18. Among the 1662 AL shortening cases, the median magnitude of the maximum AL reduction was 0.19 mm. The shortening process mostly occurred within the initial 2 years. Subject characteristics had limited associations with the shortening rate.

Conclusions

Long-term AL shortening is possible in subjects receiving myopic orthokeratology. Although age notably affect the incident probability, the time course seems to not vary significantly.

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.

Myopia Control Efficacy of Spectacle Lenses With Aspherical Lenslets: Results of a 3-Year Follow-Up Study

PURPOSE

To investigate myopia control efficacy in children who continued wearing spectacle lenses with highly aspherical lenslets (HAL) or switched from spectacle lenses with slightly aspherical lenslets (SAL) and single-vision spectacle lenses (SVL) to HAL for 1 year after a 2-year myopia control trial.

DESIGN

This was a 1-year extension of a randomized clinical trial.

METHODS

Of 54 children who had worn HAL for 2 years, 52 continued wearing HAL (HAL1 group), and of the 53 and 51 children who had originally worn SAL or SVL, 51 and 48 switched to wearing HAL (HAL2 and HAL3 groups) in year 3, respectively. A new SVL (nSVL) group of 56 children was recruited, matched for age, sex, cycloplegic spherical equivalent refraction (SER), and axial length (AL) of the HAL3 group at extension baseline, and used for a comparison of third-year changes. SER and AL were measured every 6 months in year 3.

RESULTS

During year 3, the mean (SE) myopia progression in the nSVL group was -0.56 (0.05) diopters (D). Compared with nSVL, the changes in SER were less in HAL1 (-0.38 [0.05] D, P = .02), HAL2 (-0.36 [0.06] D, P = .01), and HAL3 (-0.33 [0.06] D, P = .005). The mean (SE) AL elongation in the nSVL group was 0.28 (0.02) mm. Compared with nSVL, the elongation in AL was less in the HAL1 (0.17 [0.02] mm, P < .001), HAL2 (0.18 [0.02] mm, P < .001), and HAL3 (0.14 [0.02] mm, P < .001) groups. Myopia progression and axial elongation were comparable in all 3 HAL groups (all P > .05) in year 3.

CONCLUSIONS

Myopia control efficacy has remained in children who wore HAL in the previous 2 years. Children who switched from SAL or SVL to HAL in year 3 had slower myopia progression and axial elongation than that in the control group.

Combined 0.01% atropine with orthokeratology in childhood myopia control (AOK) study: A 2-year randomized clinical trial

BACKGROUND

To investigate whether combining 0.01% atropine with orthokeratology (AOK) has a better effect in retarding axial elongation, compared with orthokeratology alone (OK) over two years.

METHODS

A total of 96 Chinese children aged six to < 11 years with myopia (1.00 - 4.00 D, inclusive) were randomized into either the AOK or OK group in a 1:1 ratio. Axial length (the primary outcome), and secondary outcomes (e.g. pupil size and choroidal thickness) were measured at 1-month and at 6-monthly intervals after commencement of treatment.

RESULTS

Both intention-to-treat and per-protocol analyses showed significantly slower axial elongation in the AOK group than OK group over two years (P = 0.008, P < 0.001, respectively). AOK subjects had statistically slower axial elongation (adjusted mean [standard error], 0.17 [0.03] mm vs 0.34 [0.03] mm, P < 0.001), larger increase in mesopic (0.70 [0.09] mm vs 0.31 [0.09] mm, P = 0.003) and photopic pupil size (0.78 [0.07] mm vs 0.23 [0.07] mm, P < 0.001), and greater thickening of the choroid (22.6 [3.5] µm vs -9.0 [3.5] µm, P < 0.001) than OK subjects over two years. Except for a higher incidence of photophobia in the AOK group (P = 0.006), there were no differences in the incidence of any other symptom or adverse events between the two groups. Slower axial elongation was associated with a larger increase in the photopic pupil size and a greater thickening in the choroid in the AOK group.

CONCLUSIONS

Slower axial elongation following 2-year AOK treatment may result from increased pupil dilation and a thickening in the choroid observed in the AOK group.

Higher-Order Aberrations and Visual Performance in Myopic Children Treated With Aspheric Base Curve-Designed Orthokeratology

OBJECTIVES

To investigate the impact of aspheric base curve (BC)-designed orthokeratology (ortho-k) (AOK) lenses on higher-order aberrations (HOA) at different pupil diameters and visual performance.

METHODS

This prospective clinical study included subjects randomized to wear spherical BC-designed ortho-k (SOK) or AOK lenses. The Pediatric Refractive Error Profile (PREP) questionnaire was completed before and after 3 months of lens wear. The Strehl ratio (SR) and root mean square of ocular higher-order aberrations (HOAs), spherical aberration (SA), coma, and trefoil were measured under 4-mm, 5-mm, and 6-mm pupil diameters at baseline and 3-month visits. Corneal topography, uncorrected low-contrast (LC) visual acuity (VA), and high-contrast (HC) VA were measured at baseline and at 1 day, 1 week, 1 month, and 3 month follow-ups.

RESULTS

Sixty-five participants completed the study. After 3 months with the ortho-k lens, there were no significant differences in ocular HOA, SA, coma, or trefoil between the SOK group and AOK group at 4-mm, 5-mm, and 6-mm pupil diameters (all P>0.05), except for a significant increase in SA in the AOK group (P=0.01). Stratified analyses showed that the AOK group exhibited greater HOA and SA at 5-mm and 6-mm pupil diameters in the lower myopia subgroup and greater SA at 6 mm in the higher myopia subgroup (all P<0.05). There were no significant differences between the groups in SR, HC VA, LC VA, or PREP scores (all P>0.05).

CONCLUSION

Aspheric BC-designed ortho-k lenses produced a significantly greater SA than SOK lenses, with more significance at lower diopters, without sacrificing subjective visual performance.