Effect of Orthokeratology on Axial Length Elongation in Anisomyopic Children.Optom Vis Sci. 2019;96:43-47. [PMID: 30570595 DOI: 10.1097/OPX.0000000000001315]

Anisomyopia and orthokeratology for myopia control - Axial elongation and relative peripheral refraction

PURPOSE

To investigate axial elongation (AE) and changes in relative peripheral refraction (RPR) in anisomyopic children undergoing orthokeratology (ortho-k).

METHODS

Bilateral anisomyopic children, 7-12 years of age, were treated with ortho-k. Axial length (AL) and RPR, from 30° nasal (N30°) to 30° temporal (T30°), were measured at baseline and every 6 months over the study period. AE, changes in RPR and changes in the interocular AL difference were determined over time.

RESULTS

Twenty-six of the 33 subjects completed the 2-year study. The AE of the higher myopic (HM) eyes (at least 1.50 D more myopia than the other eye) (0.26 ± 0.29 mm) was significantly smaller than for the less myopic (LM) eyes (0.50 ± 0.27 mm; p = 0.003), leading to a reduction in the interocular difference in AL (p = 0.001). Baseline RPR measurements in the HM eyes were relatively more hyperopic at T30°, N20° and N30° (p ≤ 0.02) and greater myopic shifts were observed at T20° (p < 0.001), T30° (p < 0.001), N20° (p = 0.02) and N30° (p = 0.01) after lens wear. After 2 years of ortho-k lens wear, temporal-nasal asymmetry increased significantly, being more myopic at the temporal locations in both eyes (p < 0.001), while AE was associated with the change in RPR at N20° (β = 0.134, p = 0.01). The interocular difference in AE was also positively associated with the interocular difference in RPR change at N30° (β = 0.111, p = 0.02).

CONCLUSIONS

Ortho-k slowed AE in bilateral anisomyopia, with slower growth in the HM eyes leading to a reduction in interocular AL differences. After ortho-k, RPR changed from hyperopia to myopia, with greater changes induced in the HM eyes, and slower AE was associated with a more myopic shift in RPR, especially in the nasal field of both eyes.

Benefits and risks of orthokeratology treatment: a systematic review and meta-analysis

BACKGROUND

This meta-analysis reviews the evidence for the risks and benefits associated with orthokeratology (OK) treatment compared with other methods of myopia control in children and adults.

METHODS

A systematic search of Cochrane Central Register of Controlled Trials, Pubmed, Embase and Ovid was conducted from database inception to 22nd August 2021. Studies that reported on risks, visual and ocular biometric effects of OK in patients > 5 years of age with myopia (- 0.75 to - 6.00D) were included. Main outcomes are change in axial length and any adverse event.

RESULTS

Fourty-five papers were included in this systematic review and meta-analysis. The quality of data was variable and of moderate certainty, and selection bias likely skewed the results towards a relative benefit for OK. The rate of axial elongation in children was lower for OK treatment compared to other treatment modalities at one year (MD - 0.16 mm, 95% CI - 0.25 to - 0.07). Rate of change in axial length in children rebounded after OK discontinuation compared to participants who continued treatment (MD 0.10 mm, 95% CI 0.06 to 0.14). Adults and children wearing OK were up to 3.79 times more likely to experience an adverse event when compared with conventional contact lenses (OR 3.79, 95% CI 1.24 to ll.), though this evidence base is underdeveloped and requires additional well-designed studies for substantial conclusions to be drawn.

CONCLUSIONS

OK arrests myopia progression while in use, however, there remain unanswered questions about the optimal duration of treatment, discontinuation effects and long-term risk for adverse events.

Relative corneal refractive power shift and inter-eye differential axial growth in children with myopic anisometropia treated with bilateral orthokeratology

PURPOSE

To investigate the relationship between relative corneal refractive power shift (RCRPS) and axial length growth (ALG) in bilateral myopic anisometropes treated with orthokeratology.

METHODS

A total of 102 children with myopic anisometropia in this prospective interventional study were randomly assigned to the spectacle group and orthokeratology group. Axial length (AL) and corneal topography was measured at baseline and the 12-month follow-up visit. ALG was defined as the difference between the two measurements, and RCRPS profiles were calculated from two axial maps obtained.

RESULTS

In the orthokeratology group, the ALG in the more myopic eye (0.06 ± 0.15 mm) was significantly smaller than that in the less myopic eye (0.15 ± 0.15 mm, p < 0.001), and the interocular difference in AL significantly decreased following 1-year treatment, from 0.47 ± 0.32 to 0.38 ± 0.28 mm (p < 0.001). However, in the spectacle group, the ALG was similar between the two eyes, and the interocular difference in AL did not change significantly over one year (all p > 0.05). The interocular difference in ALG in the orthokeratology group was significantly correlated with the interocular difference in RCRPS (dRCRPS, β=-0.003, p < 0.001) and the interocular difference in baseline AL (β=-0.1179, p < 0.001), with R2 being 0.6197.

CONCLUSION

Orthokeratology was effective in decreasing the magnitude of anisometropia. The interocular variation in RCRPS is an important factor accounting for the reduction of interocular ALG difference in anisomyopic children post-orthokeratology. These results provide insight into establishing eye-specific myopia control guidelines during orthokeratology treatment for myopic anisometropes.

Changes in axial length in anisometropic children wearing orthokeratology lenses

Purpose

There is a particular anisometropia occurring in one eye with myopia, while the other eye has very low myopia, emmetropia, or very low hyperopia. It is unclear how the binocular axial length changes when these children wear unilateral OK lenses only in the more myopic eyes. This study investigates the changes in the axial elongation of both eyes.

Methods

This is a 1-year retrospective study. In total, 148 children with myopic anisometropia were included. The more myopic eyes were wearing orthokeratology lenses (treated eyes), whereas the contralateral eyes were not indicated for visual correction (untreated eyes). The untreated eyes were classified into three subgroups based on the spherical equivalent refraction (SER): low myopia (≤ -0.50 D, n = 37), emmetropia (+0.49 to -0.49 D, n = 76), and low hyperopia (≥0.50 D, n = 35). Changes in the axial length (AL) were compared between the untreated and treated eyes and among the three subgroups.

Results

The axial elongation was 0.14 ± 0.18 mm and 0.39 ± 0.27 mm in all treated and untreated eyes, respectively (p < 0.001). The interocular AL difference decreased significantly from 1.09 ± 0.45 mm at the baseline to 0.84 ± 0.52 mm at 1 year (p < 0.001). The baseline median (Q1, Q3) SER of the untreated eyes were -0.75 D (-0.56, -0.88 D), 0.00 D (0.00, -0.25 D), and +0.75 D (+1.00, +0.62 D) in low myopia, emmetropia, and low hyperopia subgroups, respectively. The axial elongation was 0.14 ± 0.18 mm, 0.15 ± 0.17 mm, and 0.13 ± 0.21 mm (p = 0.92) in the treated eyes and 0.44 ± 0.25 mm, 0.35 ± 0.24 mm, and 0.41 ± 0.33 mm in the untreated eyes (p = 0.11) after 1 year. Multivariate linear regression analyses only showed significant differences in axial elongation between the emmetropia and low myopia subgroups of untreated eyes (p = 0.04; p > 0.05 between other subgroups).

Conclusion

Unilateral orthokeratology lenses effectively reduced axial elongation in the more myopic eyes and reduced interocular AL differences in children with myopic anisometropia. The refractive state of the untreated eyes did not affect the axial elongation of the more myopic eye wearing the orthokeratology lens. In the untreated eyes, AL increased faster in the low myopia subgroup than in the emmetropia subgroup.

Machine learning models for orthokeratology lens fitting and axial length prediction

PURPOSE

In order to improve the efficiency of orthokeratology (OK) lens fitting and predict the axial length after 1 year of OK lens wear, machine learning models were proposed.

METHODS

Clinical data from 1302 myopic subjects were collected retrospectively, and two machine learning models were implemented. Demographic and corneal topographic data were collected as input variables. The output variables were the parameters of the OK lens and the axial length after 1 year. Eighty percent of input variables was used as the training set and the remaining 20% was used as the validation set. The first alignment curve (AC1) of the OK lenses, deduced using machine learning models and formula calculation, were compared. Multiple regression models (support vector machine, Gaussian process, decision tree and random forest) were used to predict the axial length after 1 year. In addition, we classified data based on lens brand, and carried out more detailed parameter fitting and analysis for spherical and toric OK lenses.

RESULTS

The OK lens fitting model showed higher (R2  = 0.93) and lower errors (mean absolute error [MAE] = 0.19, mean square error [MSE] = 0.09) when predicting AC1, compared with the formula calculation (R2  = 0.66, MAE = 0.44, MSE = 0.25). The machine learning model still had high R2 values ranging from 0.91 to 0.96 when considering the brand and design of the OK lenses. Further, the R2 value for the axial length prediction model was 0.94, which indicated that the machine learning model had high accuracy and good robustness.

CONCLUSION

The OK lens fitting model and the axial length prediction model played an important role in guiding OK lens fitting, with high accuracy and robustness in prediction performance.

The Relationship between Axis Length Difference and Refractive Error in Unilateral Myopic Anisometropic Children Treated with Orthokeratology

Purpose

To explore the correlation between the axial length (AL) difference (myopic and nonmyopic eye) and the refractive error in children with unilateral myopia anisometropia (UMA) and to elucidate its clinical application in the process of Ortho-K lenses review following nonstop wearing.

Methods

This study retrospectively analyzed the data of 70 children with UMA (age, 8-15 years) whose myopic eyes were treated with Ortho-K lenses. The spherical equivalent refractive errors (SERE) of the myopic eye ranged from -0.75 D to -4.25 D, and astigmatism was no less than -1.50 D. In addition, SERE of nonmyopic eyes were no less than -0.50 D. AL, and the refractive data of both eyes were measured at baseline. A multivariate linear regression was used to analyze the relationship between the AL difference and refractive error, and paired t-test was used to analyze the changes in AL in both eyes.

Results

Every 1 mm axial length change corresponds to -1.627 D (95% CI: -1.921 D, -1.333 D; P < 0.001) change in refractive error in children. The association between the AL change and the degree of myopia did not change with age (P=0.751). Among the 70 subjects, 51 (72.86%) had myopia in the right eye, and the 95% confidence interval (CI) for myopia occurring in the right eye was 62.4%-83.3%. The paired t-test showed that the average AL growth was significantly slower in myopic eyes treated with Ortho-K lenses than in nonmyopic eyes (t = 9.805, P < 0.001).

Conclusion

Every 1 mm AL change would cause an average refractive error increase. Age did not influence the association between AL changes and the degree of myopia. The right eye is more likely to be affected in children with UMA. The Ortho-K lens treatment slowed down the growth of AL in the myopic eye in children with UMA.

Controlling anisomyopia in children by orthokeratology: A one-year randomised clinical trial

PURPOSE

To investigate the effects of overnight orthokeratology (OK) lenses wear on the interocular axial length (AL) difference in anisomyopic children.

METHODS

Sixty anisomyopic children (8-14 years old) were enrolled in this one-year prospective, randomised controlled study. Subjects were randomly assigned to wear OK lenses (OK group) or single-vision spectacles (control group). AL was monitored at baseline and every six months using an IOL Master biometer, and axial elongation and interocular AL differences were compared between the groups.

RESULTS

In the control group, the more myopic eyes had similar axial elongation (0.36 ± 0.17 mm) to the less myopic eyes (0.37 ± 0.17 mm) at the one-year follow-up (P > 0.05). In the OK group, the less myopic eyes exhibited significantly greater axial elongation (0.24 ± 0.17 mm) than the more myopic eyes (0.13 ± 0.13 mm) at the one-year follow-up (P < 0.05). The mean interocular AL difference significantly decreased in the OK group over one year, from 0.47 ± 0.24 mm to 0.35 ± 0.22 mm (P < 0.05). However, the mean interocular AL difference decreased only slightly in the control group, from 0.56 ± 0.28 mm to 0.55 ± 0.28 mm (P > 0.05).

CONCLUSION

This randomised, controlled study demonstrated that OK reduces the interocular AL difference in anisomyopic children due to stronger myopic control of the more myopic eye.

Photopic pupil size change in myopic orthokeratology and its influence on axial length elongation

AIM

To explore the photopic pupil size behavior in myopic children undergoing overnight orthokeratology (ortho-k) over 1-year period and its effects on the axial elongation.

METHODS

A total of 202 Chinese myopic children were enrolled in this prospective clinical trial. Ninety-five subjects in ortho-k group and eighty-eight subjects in spectacle group completed the 1-year study. Axial length (AL) was measured before enrollment and every 6mo after the start of ortho-k. The photopic pupil diameter (PPD) was determined using the Pentacam AXL and measured in an examination room with lighting of 300-310 Lx. Stepwise multiple linear regression analysis was used to identify variables contribution to axial elongation.

RESULTS

Compared with spectacle group, the average 1-year axial elongation was significantly slower in the ortho-k group (0.25±0.27 vs 0.44±0.23 mm, P<0.0001). In ortho-k group, PPDs significantly decreased from 4.21±0.62 mm to 3.94±0.53 mm after 1mo of lens wear (P=0.001, Bonferroni correction) and the change lasts for 3-month visit. No significantly change during the other follow-up visits was found (P>0.05, Bonferroni correction). The 4.81 mm PPD may be a possible cutoff point in the ortho-k group. Subjects with PPD below or equal to 4.81 mm tended to have smaller axial elongation compared to subjects with PPD above 4.81 mm after 1-year period (t=-3.09, P=0.003). In ortho-k group, univariate analyses indicated that those with older age, greater degree of myopia, longer AL, smaller baseline PPD (PPD_baseline) experienced a smaller change in AL. In multivariate analyses, older age, greater AL and smaller PPD_baseline were associated with smaller increases in AL. In spectacle group, PPD tended to be stable (P>0.05, Bonferroni correction) and did not affect axial growth.

CONCLUSION

PPDs experience significantly decreases at 1-month and 3-month ortho-k treatment. Children with smaller PPD tend to experience slower axial elongation and may benefit more from ortho-k.

Repeatability of a new swept-source optical coherence tomographer and agreement with other three optical biometers

PURPOSE

To investigate the repeatability of Anterion and compare the agreement of ocular biometric measurements and predicted intraocular lens (IOL) powers with other three optical biometers.

METHODS

Flat keratometry (Kf), steep keratometry (Ks), J0 and 45 vectors, central cornea thickness (CCT), anterior chamber depth (ACD), and axial length (AL) from the Anterion, IOLMaster 700, Lenstar LS 900, and OA-2000 were recorded. The IOL powers were calculated with the Hoffer Q, Holladay 1, SRK/T, and Haigis formulas. The repeatability was evaluated using the within-subject standard deviation (Sw), repeatability coefficient (RC), coefficient of variation (COV), and intraclass correlation coefficient (ICC). Inter-device agreement between the four biometers was assessed with the 95% limits of agreement.

RESULTS

In total, 101 right eyes of 101 participants were enrolled. The Anterion showed good repeatability for all the included biometric parameters with all the CoV ≤ 0.30% and ICC ≥ 0.930 except for J45 with moderate repeatability (ICC was 0.849). Good agreement was found among the four devices for Kf, Ks, J0, J45, ACD, and AL. Generally, wide 95% LoA was found for the predicted IOL powers with the four IOL calculation formulas between the four devices.

CONCLUSIONS

The Anterion showed good repeatability of biometric measurements for most parameters. Good agreement among the four optical biometers was achieved for all the parameters except for CCT and the predicted IOL power. The AL values exhibited the best repeatability with Anterion and the best agreement among the biometers in our study.

Efficacy of long-term orthokeratology treatment in children with anisometropic myopia

AIM

To explore the efficacy of the orthokeratology lens for anisometropic myopia progression.

METHODS

A retrospective study was performed. Cycloplegic refraction and axial length (AL) were collected from 50 children (10.52±1.72y) who visited Peking University Third Hospital from July 2015 to August 2020. These children's one eyes (Group A) received monocular orthokeratology lenses at first, after different durations (12.20±6.94mo), their contralateral eyes (Group B) developed myopia and receive orthokeratology as well. The data in 1-year of binocular period were recorded. AL growth rate (difference of follow-up and baseline per month) were compared between two groups by paired t test. Interocular differences of AL were compared by Wilcoxon test.

RESULTS

During monocular period, the AL growth rate of the Group A (0.008±0.022 mm/mo) was significantly slower than that of the Group B (0.038±0.018 mm/mo; P<0.0001). However, during binocular period, the AL growth rate of the Group A (0.026±0.014 mm/mo) was significantly faster than that of the Group B (0.016±0.015 mm/mo; P<0.0001). The AL difference between both eyes was 0.6 (0.46) mm, then significantly decreased to 0.22 (0.39) mm when started binocular treatment (P<0.0001). However, it was significantly increased to 0.30 (0.32) mm after a year (P<0.0001), but still significantly lower than baseline (P<0.0001).

CONCLUSION

The orthokeratology lens is efficient for control the AL elongation of monocular myopia eyes and reduce anisometropia. For the condition that the contralateral eyes develop myopia and receive orthokeratology lens later, there is no efficiency observed on control interocular difference of AL during binocular treatment.

Orthokeratology Lenses Versus Administration of 0.01% Atropine Eye Drops for Axial Length Elongation in Children With Myopic Anisometropia

OBJECTIVE

To investigate the effect of orthokeratology (OK) lenses and that of 0.01% atropine eye drops on axial length (AL) elongation in children with myopic anisometropia.

METHODS

Ninety-five children with myopic anisometropia who used OK lenses (N=49) or 0.01% atropine eye drops (N=46) were enrolled in this retrospective 1-year study. For all children, the eyes with higher spherical equivalent refractive error (SER) were assigned to the H-eye subgroup, whereas the fellow eyes with lower SER were assigned to the L-eye subgroup.

RESULTS

After 1-year treatment, the mean change in the AL of H eyes and L eyes in the OK lenses group was 0.18±0.16 mm and 0.24±0.15 mm, respectively (P=0.15), and 0.28±0.20 mm and 0.25±0.18 mm, respectively (P=0.48), in the 0.01% atropine group. Multivariate regression analyses showed significant differences in AL change between H and L eyes after treatment with OK lens (P=0.03), whereas no significant difference in the 0.01% atropine (P=0.22). The change in the AL in the H-eye group was less with OK lenses than with 0.01% atropine (P=0.04), whereas there was no significant difference between the change in AL in the L-eye group between treatment with OK lens and 0.01% atropine (P=0.89).

CONCLUSIONS

In myopic anisometropic children, AL differences between 2 eyes decrease by wearing OK lenses but do not change after administration of 0.01% atropine eye drops. The increased effect of OK lenses, but not 0.01% atropine, in reducing axial elongation at 1 year in the eye with higher SER in anisometropic children warrants further investigation.

Novel application of multispectral refraction topography in the observation of myopic control effect by orthokeratology lens in adolescents

BACKGROUND

Myopia, as one of the common ocular diseases, often occurs in adolescence. In addition to the harm from itself, it may also lead to serious complications. Thus, prevention and control of myopia are attracting more and more attention. Previous research revealed that single-focal glasses and orthokeratology lenses (OK lenses) played an important part in slowing down myopia and preventing high myopia.

AIM

To compare the clinical effects of OK lenses and frame glasses against the increase of diopter in adolescent myopia and further explore the mechanism of the OK lens.

METHODS

Changes in diopter and axial length were collected among 70 adolescent myopia patients (124 eyes) wearing OK lenses for 1 year (group A) and 59 adolescent myopia patients (113 eyes) wearing frame glasses (group B). Refractive states of their retina were inspected through multispectral refraction topography. The obtained hyperopic defocus was analyzed for the mechanism of OK lenses on slowing down the increase of myopic diopter by delaying the increase of ocular axis length and reducing the near hyperopia defocus.

RESULTS

Teenagers in groups A and B were divided into low myopia (0D - -3.00 D) and moderate myopia (-3.25D - -6.00 D), without statistical differences among gender and age. After 1-year treatment, the increase of diopter and axis length and changes of retinal hyperopic defocus amount of group A were significantly less than those of group B. According to the multiple linear analysis, the retinal defocus in the upper, lower, nasal, and temporal directions had almost the same effect on the total defocus. The amount of peripheral retinal defocus (15°-53°) in group A was significantly lower than that in group B.

CONCLUSION

Multispectral refraction topography is progressive and instructive in clinical prevention and control of myopia.

Effect of orthokeratology on anisometropia control: A meta-analysis

BACKGROUND

The effectiveness of orthokeratology in retarding anisometropic progression has been investigated in several small-sample studies. This quantitative analysis aimed to elucidate the efficacy of orthokeratology for anisometropia control.

METHODS

We searched PubMed, Embase, and Cochrane databases for relevant studies through September 2020. Axial length (AL) data at baseline and final follow-up were extracted, and AL elongation and difference were calculated. Methodological quality was evaluated using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool. Meta-analyses were performed using a fixed-effect model based on the heterogeneity.

RESULTS

A total of 10 cohort studies (nine retrospective studies; one prospective study) were included. The pooled results for the unilateral myopia group showed that the mean AL elongation difference between myopic and emmetropic eyes was -0.27 mm (95% CI, -0.31 to -0.22; p < 0.01) at the one-year follow-up (four studies) and -0.17 mm (95% CI, -0.33 to -0.02; p = 0.03) at the two-year follow-up (two studies). In the bilateral anisomyopic group, mean AL elongation difference between high and low myopic eyes was -0.06 mm (95% CI, -0.09 to -0.04; p < 0.01) at the one-year follow-up (seven studies) and -0.13 mm (95% CI, -0.21 to -0.06; p < 0.01) at the two-year followup (three studies).

CONCLUSION

This study demonstrated that orthokeratology can effectively retard myopic progression and reduce anisomyopic values. However, additional wellstructured randomized controlled trials or prospective studies with longer follow-up periods are warranted to address this topic in more detail.

A comparative study of orthokeratology and low-dose atropine for the treatment of anisomyopia in children

Myopic anisometropia (anisomyopia) is a specific type of refractive error that may cause fusion impairment, asthenopia, and aniseikonia. It is sometimes severe enough to reduce the quality of life. Several studies have investigated the treatment effects of orthokeratology (Ortho-K) and topical atropine on anisomyopia control. However, no study has compared these two interventions simultaneously until now. The cohort of this retrospective study included 124 children with anisomyopia who were treated with binocular Ortho-K lenses, 0.01% atropine, or 0.05% atropine. After a 2-year follow-up, the inter-eye difference in axial length (AL) significantly decreased in the Ortho-K group (P = 0.015) and remained stable in the two atropine groups. When comparing the myopia control effect, the use of Ortho-K lenses resulted in an obviously smaller change in AL than the use of 0.01% and 0.05% atropine (P < 0.01). Ortho-K treatment may reduce the degree of anisomyopia and stabilise the progression of myopia. Hence, Ortho-K might be a better choice for anisomyopic children.

Pattern of Axial Length Growth in Children Myopic Anisometropes with Orthokeratology Treatment

PURPOSE

To compare the pattern of growth in axial length (AL) between children with anisometropia who wear orthokeratology (OK) lenses and those who wear spectacles (SP).

METHODS

A retrospective study was conducted. Data of baseline and 1 year from 252 children (8-14 years old) anisomyopes who sought refraction corrections at the Zhongshan Ophthalmic Center between October 2013 and June 2017 were reviewed. Seventy-nine unilateral myopic anisometropes (UMA) and 98 bilateral myopic anisometropes (BMA) treated with OK lenses were set as study groups (OK-UMA and OK-BMA groups). Age, refraction, and AL-matched unilateral (n = 38) and bilateral myopic anisometropes (n = 37) treated with spectacles were set as control groups (SP-UMA and SP-BMA groups). The 1-year change in AL between the study and control groups (OK-UMA vs. SP-UMA and OK-BMA vs. SP-BMA) was compared.

RESULTS

There were no significant differences in the baseline of age, refraction, and AL between OK-UMA and SP-UMA or OK-BMA and SP-BMA groups (all P > .05). Compared to the SP-UMA group, annual axial elongation of the myopic eyes of the OK-UMA group was smaller (0.05 ± 0.19 mm vs. 0.33 ± 0.29 mm, P < .001); however, AL elongation in the non-myopic eyes were comparable between SP-UMA and OK-UMA groups (P > .05). At the end of 1 year, the interocular difference in AL (aniso-AL) decreased by 0.29 ± 0.29 mm (P < .001) in the OK-UMA group but remained unchanged in SP-UMA group. Compared to the SP-BMA group, annual axial elongations of both eyes of the OK-BMA group were smaller (the more myopic eye, 0.05 ± 0.17 mm vs. 0.38 ± 0.21 mm; the less myopic eye, 0.15 ± 0.19 mm vs. 0.35 ± 0.28 mm; both P < .001). At the end of 1 year, aniso-AL decreased by 0.10 ± 0.15 mm (P < .001) in the OK-BMA group but remained unchanged in the SP-BMA group.

CONCLUSION

Orthokeratology is effective in reducing the interocular difference in AL of children anisomyopes through greater retardation of axial elongation of the more myopic eyes.

Effects of orthokeratology lens on axial length elongation in unilateral myopia and bilateral myopia with anisometropia children

PURPOSE

To investigate the effect of orthokeratology (OK) lens on axial length (AL) elongation in unilateral myopia and bilateral myopia with anisometropia children.

METHODS

Twenty-seven unilateral myopia (group 1) and 25 bilateral myopia with anisometropia children (group 2) were involved in this 1-year retrospective study. The eyes with higher spherical equivalent refractive error (SER) were assigned to the H eyes subgroup and the fellow eyes with lower SER to the L eyes subgroup in the two groups.

RESULTS

The mean change in AL of H eyes and L eyes were 0.11 ± 0.19 mm, 0.30 ± 0.28 mm in group 1 (P = 0.04) and 0.09± 0.14mm, 0.13± 0.16mm in group 2 (P = 0.36), respectively. Multivariate regression analyses showed that significant difference of change in AL was found between H eyes and L eyes in group1 (β=0.25, P = 0.03), but no difference in group 2 (β=0.09, P = 0.12). The AL of H eyes in group 1 and group 2, H eyes in group 1 and L eyes in group 2 had the same increased rate (β= -0.04, P = 0.43; β = 0.02, P = 0.56).

CONCLUSIONS

Monocular OK lens is effective on suppression AL elongation of the myopic eyes and reduce anisometropia value in unilateral myopic children. The OK lens can control the AL elongation in both eyes at the same rate, but it cannot reduce anisometropia value in bilateral myopia with anisometropia children after 1-year follow-up.