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Purpose: To compare the safety and efficacy of the trial lens-fitting and software-fitting in orthokeratology for myopia control in children with high corneal eccentric value., Methods: Myopic children with high corneal eccentric value (≥0.65) receiving treatment for orthokeratology from July 2020 to January 2022 were included in this retrospective study. Only the right eyes were included. The participants were allocated into two groups: the trial lens-fitting group (n = 41) and the software-fitting group (n = 48). The uncorrected visual acuity (UCVA), corneal topography, and ocular health (Efron grading scales) were recorded at baseline, one week, two weeks, one, three, six, and 12 months afterthe initiation of lens wear. The axial length and endothelial cell density were assessed at baseline and after 12 months of lens wear., Results: The success rate of the first fit in the software-fitting group and trial lens-fitting group reached 98 % and 95 %, respectively. The difference in UCVA and corneal staining were statistically insignificant between the two groups during all visits. The software-fitting group exhibited a smaller treatment zone size (radius 1.69 ± 0.21 mm vs 1.81 ± 0.16 mm, p = 0.004; area 9.13 ± 2.15 mm 2 vs 10.36 ± 1.82 mm 2 , p = 0.005) and less decentration (0.58 ± 0.31 mm vs 0.74 ± 0.39 mm, p = 0.036) compared with the trial lens-fitting group. There were no significant differences in axial elongation (0.15 ± 0.12 mm vs. 0.17 ± 0.14 mm, p = 0.534) or changes in endothelial cell density (-36.63 ± 99.37/mm 2 vs - 13.71 ± 87.72/mm 2 , p = 0.256) between the software-fitting group and the trial lens-fitting group at one-year follow-up visit., Conclusion: Both fitting methods were effective and safe. However, the software-fitting method resulted in a smaller treatment zone size and less decentration., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: Non-adherence to standard wear, care, and follow-up procedures is a major risk factor for contact lens-related complications. The effectiveness of orthokeratology largely depends on the wearer's adherence. However, a deficiency in scales capturing adherence beliefs pertinent to orthokeratology exacerbates the lack of guidance for effective intervention strategies. The purpose of this study is to develop and evaluate the psychometric properties of a new scale based on the Theory of Planned Behavior that assesses the level of adherence among ortho-k wearers., Methods: This study involved three stages following the STROBE checklist: (1) developing initial scale items based on the Theory of Planned Behavior, a literature review, and a qualitative study; (2) evaluation of content and face validity; (3) psychometric testing on 296 participants. Item analysis, based on Classical Test Theory, assessed the overall consistency, reliability, and validity of the scale., Results: The final 37-item Beliefs about the Orthokeratology Lens Compliance Scale (BOLCS) comprises 11 dimensions. The Cronbach's alpha coefficients for each dimension ranged from 0.560 to 0.798. The folded half reliabilities were 0.845, and the combined reliabilities ranged from 0.676 to 0.793, indicating strong reliability. Item-level CVI (I-CVI) and scale-level CVI/average (S-CVI/Ave) values, assessed by the panel, ranged from 0.71 to 1 and 0.954, respectively. Exploratory and confirmatory factor analyses supported a factor structure consistent with the theoretical model., Conclusions: The scale's construction adhered to a standardized process, yielding preliminary validation results with satisfactory reliability and validity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

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., (Copyright © 2024 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To discuss the characteristics of anterior corneal elevation asymmetry in myopic eyes and clarify which kind of asymmetry most influenced lens position., Methods: In this retrospective study of 199 consecutive myopic participants, corneal topography was used to analyse asymmetry in anterior corneal elevation. Amongst them, 65 participants (65 eyes) who underwent orthokeratology (31 and 34 with spherical and toric lenses, respectively) were re-evaluated. Stepwise multiple linear regression analysis was used to identify the contributing factors that influenced lens decentration. Receiver operating characteristic curve (ROC) analysis was employed to assess how the corneal asymmetry vector could predict decentration., Results: There were no significant differences in treatment zone decentration (TZDec) between participants wearing toric and spherical lenses (p = 0.60 and 0.64 for 1 week and 1 month of wear, respectively). Amongst the underlying factors, the magnitude of TZDec was only correlated with the amount of corneal asymmetry vector (standardised β = 0.44, 0.48, p < 0.001 for all) after 1 week and 1 month of wear, and the direction of TZDec after 1 month of lens wear was associated with the angle of the asymmetry vector (r = 0.25, p = 0.04). ROC analysis showed that the magnitude of corneal asymmetry vector produced accurate discrimination between non-severe and severe decentration for 1 week and 1 month of wear (area under the curve was 0.93 ± 0.04 and 0.89 ± 0.05, respectively, p < 0.001). Amongst participants whose corneal asymmetry vector exceeded 41.06 μm and was oriented inferiorly, 35.29% showed severe decentration after 1 month of lens wear., Conclusions: In myopic participants, corneal asymmetry existed in the 8.0 mm chord diameter. If the asymmetry vector >41.06 μm and the direction was oriented inferiorly, then practitioners must be vigilant about severe decentration which would not be alleviated by a toric design., (© 2024 College of Optometrists.)

Purpose: Rigid contact lenses have an important role in contact lens practice. The purpose of this work is to update earlier surveys by describing global trends in rigid lens fitting between 2000-2023., Method: An annual contact lens prescribing survey was sent to eye care practitioners in up to 71 countries between 2000 and 2023. Data relating to 342,500 fits undertaken in 20 countries returning reliable longitudinal data were analysed in respect of rigid lens fitting, defined as the fitting of any design of a contact lens manufactured in a rigid material., Results: Overall, rigid lens prescribing increased slightly over time, from 14.2 % of lens fits in 2000 to 15.2 % in 2023 (p < 0.0001). However, post-hoc analysis shows that the change over time is best described as a decline between 2000 and 2012, followed by a steady increase subsequently. There were significant differences in rigid lens prescribing between countries (p < 0.0001). The difference between the percentage of males fitted with rigid lenses, as a proportion of all contact lenses (12.7 %), and females (12.0 %) is significant (p < 0.0001), although not clinically meaningful. Rigid lens wearers are older at fitting than soft lens wearers (38.7 vs 31.3 years, respectively) (p < 0.0001). Analysis of 5,994 rigid lens fits prescribed currently (2019-2023) were categorised as: corneal sphere - 30 %; scleral and corneo-scleral - 28 %; corneal myopia control/orthokeratology - 21 %; and corneal complex (including toric, multifocal and monovision) - 16 %., Conclusion: There has been a slight increase in rigid lens fitting during the second decade of this century. This increase is apparently due to a 'repurposing' of rigid lenses, with the growth of scleral/corneo-scleral and myopia control/orthokeratology lens fits essentially replacing conventional spherical corneal lens fits., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Nathan Efron: Over the past three years Professor Efron has received honoraria from CooperVision. Philip B. Morgan: Over the past three years Professor Morgan’s research group or he personally has received funding or honoraria from: Alcon, Clearlab CooperVision, Daysoft, Johnson & Johnson Vision, Menicon, and Visco Vision. He is a director of M-Optometry Limited. Craig Woods: Over the past 3 years Prof Woods has acted as a consultant for the Brien Holden Vision Institute and Zeiss Vision Care. Deborah Jones: Over the past 3 years Dr Jones has received honoraria from Hoya, Essilor, CooperVision, Alcon and SIghtglass. Lyndon Jones: Over the past three years, Dr Jones’ research group (CORE) or he personally has received research support or lectureship honoraria from Alcon, Azura Ophthalmics, Bausch & Lomb, CooperVision, Essilor, Hoya, iMed Pharma, Integral Biosystems, Johnson & Johnson Vision, Menicon, Novartis, Ophtecs, Ote Pharma, Santen, SightGlass, SightSage, Topcon and Visioneering. Dr Jones is also a consultant and/or serves on an advisory board for Alcon, CooperVision, Johnson & Johnson Vision, Novartis and Ophtecs. Over the last 12 months, Jason Nichols: Dr Jason Nichols has nothing to report. Also, Dr. Kelly Nichols is the spouse of Dr. Jason Nichols, extending her declarations to him. In the past 12 months, Dr Kelly Nichols has consulted for and received honorarium from: Abbvie, Alcon, Alderya, Azura, Bausch + Lomb, Bruder, Cavalry, Dompe, HanAll Bio, Harrow, Novartis, Novaliq, Oyster Point Pharma/Viatris, Sydnexis, Tarsus, TearSolutions, Thea, Topcon, and Trukera. She has received research funding from: Aramis, Kowa, Science Based Health, Sylentis, and TearScience., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

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 mm 2 and 20.61 ± 4.54 mm 2 , 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Purpose: A hospital-based survey to explore lens rinsing habits of orthokeratology (ortho-k) patients, including the solution used for rinsing., Methods: An anonymous survey, via an online questionnaire, was administered to ortho-k lens wearers or their parents when they attended Fudan University Eye and ENT Hospital for routine follow-up visits. Three major issues were investigated: basic demographics, lens rinsing solution used, and specific rinsing habits. Relationships between demographics and rinsing solution used and rinsing behaviours were explored., Results: Of the total of 541 online questionnaires delivered, 296 were completed and returned. The respondents were the person responsible for lens care, either the ortho-k users themselves, or their parents. The median age of the lens wearers was 12.0 years (range: 8-22 years), and the median period of ortho-k lens wear was 18.0 months (range: 1-109 months). The most common rinsing solutions reported were a particular brand of multidose preserved saline (28.4%), cooled boiled water (23.3%), and non-preserved multidose saline (16.2%). Overall, the main reason for choice of rinsing solution was recommendation of eye care practitioners (90.2%). The respondents with a longer lens wear history tended to use commercially available bottled water, drinking water, or cooled boiled water rather than non-preserved saline (unidose or multidose) (p ≤ 0.009) and were more likely to use the rinsing solution to soak their lenses (p = 0.009). Lens wearers who rinsed the lenses themselves tended to use tap water compared to those whose lenses were handled by parents (p = 0.040)., Conclusion: Inappropriate choice and usage of rinsing solution appeared to be a common issue among ortho-k lens wearers in Shanghai, China. The problem was more pronounced in long-term wearers and in those who performed rinsing themselves., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

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 (C weighteddefocus )., 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 C weighteddefocus 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 C weighteddefocus (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 C weighteddefocus (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 C weighteddefocus 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 C weighteddefocus 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 C weighteddefocus at 12 months., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Objective: To estimate the original corneal curvature after orthokeratology by applying a machine learning-based algorithm., Methods: A total of 497 right eyes of 497 patients undergoing overnight orthokeratology for myopia for more than 1 year were enrolled in this retrospective study. All patients were fitted with lenses from Paragon CRT. Corneal topography was obtained by a Sirius corneal topography system (CSO, Italy). Original flat K (K1) and original steep K (K2) were set as the targets of calculation. The importance of each variable was explored by Fisher's criterion. Two machine learning models were established to allow adaptation to more situations. Bagging Tree, Gaussian process, support vector machine (SVM), and decision tree were used for prediction., Results: K2 after one year of orthokeratology (K2 after ) was most important in the prediction of K1 and K2. Bagging Tree performed best in both models 1 and 2 for K1 prediction (R = 0.812, RMSE = 0.855 in model 1 and R = 0.812, RMSE = 0.858 in model 2) and K2 prediction (R = 0.831, RMSE = 0.898 in model 1 and R = 0.837, RMSE = 0.888 in model 2). In model 1, the difference was 0.006 ± 1.34 D (p = 0.93) between the predictive value of K1 and the true value of K1 (K1 before ) and was 0.005 ± 1.51 D(p = 0.94) between the predictive value of K2 and the true value of K2 (K2 before ). In model 2, the difference was -0.056 ± 1.75 D (p = 0.59) between the predictive value of K1 and K1 before and was 0.017 ± 2.01 D(p = 0.88) between the predictive value of K2 and K2 before ., Conclusion: Bagging Tree performed best in predicting K1 and K2. Machine learning can be applied to predict the corneal curvature for those who cannot provide the initial corneal parameters in the outpatient clinic, providing a relatively certain degree of reference for the refitting of the Ortho-k lenses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Purpose: There are limited reports available on the impact of wearing Orthokeratology (ortho-K) lenses on the quality of life of Asian children. This study evaluated and compared vision-related quality of life (VRQoL) between myopic children wearing ortho-K lenses and single-vision spectacles (SVSs), living in Kuala Lumpur, using Paediatric Refractive Error Profile (PREP) questionnaires., Methods: This is a cross sectional study. Myopic children who had been wearing ortho-K and SVSs for 12 months were recruited, and the questionnaires were distributed online. The PREP scores were obtained using a summary scoring method. The Shapiro-Wilk test was used to determine data normality. Unpaired t-test was performed for normally distributed data, and the Mann-Whitney test for non-normally distributed data. P < 0.05 was considered significant., Results: A total of 70 subjects participated in this study (45 ortho-K and 25 SVSs), with a mean age of 10.86 ± 0.73 years. The mean scores for all the items were higher in ortho-K than SVS wearers (p < 0.05). With regard to symptoms during ortho-K lens wear at night, <10 % of the subjects reported difficulty falling asleep, itch/burning/dry eyes and foreign body sensation after lens insertion., Conclusion: Ortho-K improves the vision-related quality of life of myopic school children in Kuala Lumpur. Thus, it should be considered by more local optometrists when managing myopic children., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To assess the tear film surface quality after orthokeratology using an automated Medmont E300 corneal topographer., Methods: Children who wore orthokeratology lenses for more than one year were selected in this retrospective study. Tear film disruption (TFD) and central tear film disruption (cTFD) were measured with Medmont E300 corneal topographer at initial and each follow-up visit after fitting with orthokeratology lenses, providing a nominal value from 0 (perfect) to 1 (poor). Tear film surface quality before and after ortho-k treatment was compared., Results: 145 children using orthokeratology lenses were observed. TFD and cTFD significantly increased at 1-day follow up (TFD, t = -17.3, P < 0.001; cTFD, t = -10.4, P < 0.001). This change remained consistent through to 12-months visit (TFD, F = 51.1, P < 0.001; cTFD, F = 28.0, P < 0.001). A sub-group of n = 11 children were discontinued for 1-month before being refit with OrthoK lenses of a different design. Similarly, there was a significant increase in TFD compared to pre-orthoK scans (0.172 ± 0.161), but this returned to baseline levels after ceasing lens wear (0.084 ± 0.059). A sub-group of monocular OrthoK wearers (n = 23) found that TFD and cTFD values increased in eyes with monocular lens-wearing but remained stable in the lateral eyes., Conclusions: Objective measurements of tear-film quality are reduced in children after fitting with orthokeratology lenses, but return to baseline after 1-month of lens cessation. It is of importance to ensure tear film surface quality is continuously monitored throughout use of orthoK lenses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To investigate the relationship between myopia progression and axial length (AL) elongation in orthokeratology (ortho-k) patients., Methods: This study investigated 184 patients (baseline age 9.0 ± 1.6 years), who underwent overnight ortho-k treatment for 12 to 72 months, and stopped lens wear for 1 to 2 months. Refractive sphere and cylinder after cycloplegia, corneal curvatures along both meridians, and AL were compared before the commencement and after discontinuation of ortho-k treatment. The effects of AL change, baseline AL, corneal curvature change, baseline age, and duration of ortho-k treatment on the change in spherical equivalent refractive error (SER) were analysed., Results: Myopia significantly progressed and AL increased following 32.8 ± 13.0 months of ortho-k lens wear and 1 to 2 months washout period, as compared to baseline (all P < 0.001). Corneal curvature along the flat meridian (FK) became significantly flatter (P < 0.001) and corneal curvature along the steep meridian (SK) became steeper (P = 0.036). In the first stepwise multiple linear regression model (R 2  = 0.696), the change in SER over time (ΔSER) is significantly correlated to the change in AL (ΔAL, P < 0.001), baseline AL (P < 0.001), baseline age (P = 0.028), change in SK (P = 0.002), and the duration of ortho-k lens treatment before discontinuation (P = 0.010). In a more simplified model (R 2  = 0.628), the regression equation using ΔAL to predict ΔSER is: ΔSER = -0.094-1.608*ΔAL., Conclusions: The change in SER was significantly correlated to the change in AL, change in SK, baseline AL, baseline age, and the duration of treatment among children undergoing ortho-k therapy. The ratio of axial elongation to myopia progression was approximately 1:1.6 between the ages of 6 to 14 years. A simplified equation was derived for clinical use to estimate myopia progression from repeated AL measurement in ortho-k patients., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier Ltd.)

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 (Z 3 1 ). 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 (Z 3 1 ). 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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Orthokeratology (ortho-k) is an overnight clinical contact lens wear technique to correct myopia and to reduce myopia progression wearing reverse-geometry rigid gas-permeable lenses. The lens fitting procedure in clinical practice usually requires subjective assessment of fluorescein pattern (fluorescein "bull's eye" pattern). The aim of this study was to develop a novel tool for fluorescein pattern measurements to reduce subjective practitioner dependency, especially in inexperienced practitioners, in ortho-k practice., Methods: A new MATLAB customized algorithm to measure the horizontal width of the four main zones of ortho-k fluorescein patterns (central bearing, tear reservoir, mid-peripheral bearing and edge lift) was designed. The algorithm was tested on a small image database consisting of 26 ortho-k fluorescein pattern images of 13 volunteers fitted with reverse geometry lenses (Seefree, Conoptica-Hecht Contactlinsen). The agreement between two independent observers and the ImageJ measurements was determined., Results: The new clinical tool provided similar measurements to ImageJ software for the central bearing (4.20 ± 0.74 and 4.27 ± 0.69 mm; P = 0.21), tear reservoir (1.69 ± 0.41 and 1.69 ± 0.45 mm; P = 0.69), mid-peripheral bearing (1.17 ± 0.11 and 1.13 ± 0.10 mm; P < 0.01) and edge lift (0.48 ± 0.06 and 0.48 ± 0.06 mm; P = 0.81) zones. Good agreement between the software (limits of agreement lower than ±0.55 mm) and inter-observer measurements (limits of agreement lower than ±0.66 mm) was found., Conclusions: The proposed clinical tool for semiautomatic fluorescein pattern measurements in ortho-k could help to reduce practitioner dependency in fluorescein pattern assessment with future potential to introduce prediction algorithms or artificial intelligence methods in myopia control management., Competing Interests: The authors declare that they have no competing interests., (© 2022 López García Rosuero et al.)

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 = ax 2  + 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) (R 2  = 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., (© 2022 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Purpose: To investigate the reasons for wasting orthokeratology (OK) lenses due to breakage or loss, provide more comprehensive guidelines for the clinical care of lenses and minimize time and costs for patients due to excessive broken and lost lenses., Methods: A survey was administered to clinic outpatients who had broken or lost their OK lenses before the regularly scheduled replacement cycle (1-1.5 years). The association between the frequency of OK lens breakage and daily care was assessed using Fisher's exact test and multivariable ordered logistic regression analysis., Results: A total of 306 valid questionnaires were collected. Among the subjects, 141 were male, and 165 were female, with a mean age of 10.57 ± 2.00 years (range: 6-18 years). In the investigation of the causes of OK lens waste, 81.4% of the patients reported lens breakage, 13.1% lost their lenses, and 5.6% of patients experienced both fragmentation and lens loss. More than half of the patients (52.90%) used incorrect lens cleaning techniques. In further analysis of the relationship between the frequency of OK lens fragmentation within a year and daily care habits, a significant difference was observed between the caregiver ( P = 0.03) and whether the lenses were cleaned promptly after removal ( P < 0.001). Mothers as daily caregivers of OK lenses had a lower frequency of fragmentation in a year compared to nanny or grandparents ( P = 0.014, OR = 0.33, 95% CI = 0.13, 0.80). The failure to clean the lenses according to eye care practitioners' guidance was a risk factor for the frequent breakage of OK lenses ( P < 0.001. OR = 5.29, 95% CI = 3.15, 8.89)., Conclusions: The causes of OK lens waste were mainly attributed to caregivers, care practices and some unexpected situations that can be avoided through optometrists' reminders. Regardless of the reasons for noncompliant behavior leading to breakage or loss of OK lenses, all of the complications can probably be addressed by better and more frequent reinforcement of care procedures by practitioners. Better clinical guidance measures and more frequent reminders could prevent a large proportion of abnormal waste of OK lenses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fan, Zuo, Ma, Peng, Li, Wang and Zhao.)

Myopia or short-sightedness is an emerging pandemic affecting more than 50% population in South-Asian countries. It is associated with several sight-threatening complications, such as retinal detachment and choroidal neovascularization, leading to an increased burden of visual impairment and blindness. The pathophysiology of myopia involves a complex interplay of numerous environmental and genetic factors leading to progressive axial elongation. Environmental factors such as decreased outdoor activity, reduced exposure to ambient light, strenuous near work, and role of family history of myopia have been implicated with increased prevalence of this refractive error. While multiple clinical trials have been undertaken to devise appropriate treatment strategies and target the modifiable risk factors, there is no single treatment modality with ideal results; therefore, formulating a comprehensive approach is required to control the myopia epidemic. This review article summarizes the epidemiology, dynamic concepts of pathophysiology, and evolution of the treatment modalities for myopia such as pharmacological (atropine and other agents) and optical methods (spectacles, contact lenses, and orthokeratology)., Competing Interests: None

Purpose: A multi-level model was used to analyse factors, including environmental factors, affecting the controlling effect of orthokeratology on myopia progression., Methods: A 2-year prospective study was conducted in the West China Hospital, Sichuan University. Age, sex, height, baseline spherical equivalent refraction, choroidal thickness, axial length and other biometric ocular parameters were collected. Additionally, data on the following environmental factors were obtained: near-work distance and time, sleep time and time spent outdoors. After the baseline measurements, participants were followed up every 3 months for 2 years of lens wear. The primary outcome measure was axial length elongation over 2 years of orthokeratology. All variables were included in a univariate, three-level analysis model with inclusion in the final multivariate multi-level model if statistically significant., Results: Thirty-three participants (average age 9.73 ± 1.55 years) were included in this study. During the 2-year period of lens wearing, binocular changes in axial length increased significantly from the ninth month and continued until the end of the follow-up. Changes in axial length after 2 years of lens wearing were 0.44 ± 0.30 mm and 0.37 ± 0.26 mm in the right and left eyes, respectively (both p < 0.001). Based on the 2-year multi-level model, age, sex, baseline spherical equivalent refraction, flatter keratometry meridian and near-work time influence the effect of orthokeratology., Conclusions: This is the first study to use a multi-level model to analyse factors, including environmental factors, that affect myopia control using orthokeratology. These results showed that younger age, being female, having lower myopia at baseline, a steeper flattest keratometry meridian and no more than 5 h of near work per day were associated with better myopia control effect using orthokeratology over a 2-year treatment period., (© 2022 College of Optometrists.)

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., (© 2022. The Author(s).)

Purpose: To construct a machine learning (ML)-based model for estimating the alignment curve (AC) curvature in orthokeratology lens fitting for vision shaping treatment (VST), which can minimize the number of lens trials, improving efficiency while maintaining accuracy, with regards to its improvement over a previous calculation method., Methods: Data were retrospectively collected from the clinical case files of 1271 myopic subjects (1271 right eyes). The AC curvatures calculated with a previously published algorithm were used as the target data sets. Four kinds of machine learning algorithms were implemented in the experimental analyses to predict the targeted AC curvatures: robust linear regression models, support vector machine (SVM) regression models with linear kernel functions, bagging decision trees, and Gaussian processes. The previously published calculation method and the novel machine learning method were then compared to assess the final parameters of ordered lenses., Results: The linear SVM and Gaussian process machine learning models achieved the best performance. The input variables included sex, age, horizontal visible iris diameter (HVID), spherical refraction (SER), cylindrical refraction, eccentricity value (e value), flat K (K1) and steep K (K2) readings, anterior chamber depth (ACD), and axial length (AL). The R-squared values for the output AC1K1, AC1K2 and AC2K1 values were 0.91, 0.84, and 0.73, respectively. The previous calculation method and machine learning methods displayed excellent consistency, and the proposed methods performed best based on flat K reading and e values., Conclusions: The ML model can provide practitioners with an efficient method for estimating the AC curvatures of VST lenses and reducing the probability of cross-infection originating from trial lenses, which is especially useful during pandemics, such as that for COVID-19., (Copyright © 2021 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Background: To confirm the association between treatment-zone (TZ) decentration and axial length growth (ALG) in children who underwent orthokeratology; and to explore the association between TZ decentration and relative corneal refractive power (RCRP) profile, which was known to be significantly associated with ALG retardation., Methods: Four hundred myopic children of age 12 years participated in the study, with 200 wearing orthokeratology lenses and the other 200 wearing single-vision spectacle as the controls. Cycloplegic refraction was performed at baseline. Axial length was measured at baseline and 12 months after initial lens wear, and ALG was defined as the difference. In the ortho-k group, TZ decentration and the RCRP map were calculated from the topography map obtained at the 12-month visit. RCRP were summed within various chord radii from the cornea center, and the association to TZ decentration, spherical equivalent (SE), ALG were analyzed with linear regressions., Results: Compared to the controls, children wearing orthokeratology lenses had significantly smaller ALG over 1 year (0.1 ± 0.15 mm vs. 0.32 ± 0.17 mm, p < 0.001). ALG was significantly and negatively associated with summed RCRP within the central cornea of 2 mm in radius. The mean TZ decentration was 0.62 ± 0.25 mm, and the mean direction was 214.26 ± 7.39 degrees. ALG was negatively associated with the TZ decentration magnitude (p < 0.01), but not the direction (p = 0.905). TZ decentration caused an asymmetrical distribution of the RCRP with the nasal side plus power shifting towards the corneal center. For chord radius ranging 1-2 mm, the association between TZ decentration and the summed RCRP were significant, and the proportion of variance accountable increased with chord radius. For chord radius beyond 1.5 mm, the association between baseline spherical equivalent (SE) and summed RCRP was significant. The portion of variance accountable by SE increased and peaked in 2.5 mm chord radius., Conclusions: A larger TZ decentration was associated with a larger summed RCRP in the central cornea. It may be one of the possible reasons why TZ decentration is beneficial to retarding myopia progression., (© 2022. The Author(s).)

Background: To study the baseline factors that related to faster axial elongation after orthokeratology (OK) treatment and the characteristics of cases with axial length decrease in a group of myopia children., Methods: This is a retrospective study. The records of 73 children who had wear OK lens for at least one year were reviewed. Only the data of right eyes were included. Baseline data included: age, gender, parental myopia, refractive error, corneal power, central corneal thickness, axial length and anterior chamber depth. Corneal power, central corneal thickness, anterior chamber depth and axial length after one-year of OK lens wear were also collected. The related factors affecting axial length change were analyzed. A comparison was made on the cases of axial length increase and axial length decrease., Results: Of the 73 eyes, axial length increased by 0.18 ± 0.17 mm (P < 0.001) after one year of OK lens wear. Correlation analysis showed that one-year axial length change was negatively correlated with age and positively correlated with the parental myopia and baseline myopia. Stepwise multiple linear regression analysis showed that the factors associated with faster axial elongation were lower baseline myopic spherical equivalent (P = 0.018), higher parental myopia degree (P = 0.026), and younger age at the onset of lens wear. (P = 0.039). Nine eyes showed negative axial growth (-0.06 ± 0.04 mm), and had older initial age of lens wear, higher baseline myopic spherical equivalent, and lager baseline corneal power, when compared with cases of axial length increase., Conclusions: Myopia children with lower baseline myopic spherical equivalent, younger initial age and higher parental myopia had faster axial elongation after orthokeratology treatment. More aggressive treatment should be considered. In children with slow axial elongation, OK lens wear may lead to negative axial growth. Whether there are reasons other than central corneal thinning and choroidal thickening needs further study., (© 2022. The Author(s).)

Purpose: To determine the efficacy, predictability and safety of long-term orthokeratology in children and adults., Methods: Case histories of 300 orthokeratology patients (596 eyes; 34.3% children; 65.7% adults) were reviewed to collect information on demographics, corneal and refractive parameters, visual acuity, residual refraction and adverse effects. Predictability was defined as the percentage of eyes with absolute values of spherical equivalent refraction ≤ 0.5 D of emmetropia, and efficacy as the ratio of post-orthokeratology uncorrected and pre-orthokeratology corrected distance visual acuity., Results: Median duration of treatment was 37 and 28.5 months in children and adults, respectively (p = 0.022). During the first year, 17.2% of children and 33% of adults ceased lens wear (p < 0.001). For children and adults with a successful ortho-k treatment of at least one year of duration, 88.7% and 95.9% of eyes had a predictable refractive outcome, and efficacy was 0.98 and 1.01, respectively. A larger percentage of children (65.7%) were free of complications than of adults (55.4%) (p = 0.015). One event of microbial keratitis occurred in adults (6.8 cases per 10,000 patient-years) and none in children. Corneal staining was the most frequent complication, with a higher incidence in adults (p = 0.007) and in higher myopia (p < 0.001), higher anterior corneal eccentricity (p = 0.019) and smaller anterior horizontal radius (p = 0.027)., Conclusion: Orthokeratology is a safe and predictable long-term procedure in children and adults, with a low incidence of serious adverse effects. Corneal staining episodes are relatively frequent throughout the course of the treatment, thus highlighting the relevance of education of experienced users., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors have no conflicts of interest relevant to this article., (Copyright © 2021 Formosan Medical Association. Published by Elsevier B.V. All rights reserved.)

Purpose: To compare lens cleaning routines using a povidone iodine-based rigid lens disinfecting solution and its effect on conjunctival colonisation, and lens and lens case contamination., Methods: Participants, aged 6-10 years, receiving orthokeratology treatment were randomised to four lens cleaning routines: with and without the use of daily and/or weekly cleaners, which were performed by their parents. Conjunctival colonisation was compared before lens wear and at 1-, 3-, and 6-month after commencement of lens wear. Contamination of lenses and lens cases was investigated at these times. Organisms were identified using MALDI-TOF mass spectrometry., Results: Of the 76 participants who completed the study, conjunctival colonization was present in 24 (32 %) at baseline. Of the remaining 52 participants, 34 consistently yielded no growth. Participants positive at baseline were statistically more likely to be colonized after commencement of lens wear (p = 0.020). Overall, colonization rate was reduced to 15 % (11/72) after 6-month lens wear, which reached significance for initially colonized participants (p < 0.001). Few cultures yielded potential ocular pathogens, with notably no Pseudomonas aeruginosa. Contamination rates of both lenses and lens cases were also low, with few isolations of ocular pathogens. No significant differences were observed between cleaning regimes for conjunctival colonization or contamination of lenses or cases., Conclusions: Disinfection for rigid and ortho-k lens wearers may be effectively achieved with the use of povidone iodine-based solution, apparently regardless of cleaning routine adopted in the current study. The absence of pathogens in the conjunctiva, lenses, and lens cases in the great majority of samples indicates that it can improve the safety of overnight lens wear., (Copyright © 2021 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Background: Patient non-compliance, that is, failure to perform standard wear and care orthokeratology (ortho-k) lenses procedures, has been shown to be a major risk factor for contact lens-associated complications. Therefore, this study aimed to investigate the compliance with wear and care behaviors of ortho-k patients and analyze its influencing factors., Methods: Patients who were successfully prescribed ortho-k lenses at the Eye Center of the Second Affiliated Hospital of Zhejiang University School of Medicine (ECSAHZU) were enrolled in the study. Patient compliance with wear and care behaviors was examined through a questionnaire., Results: This study assessed 238 subjects. The subjects' ages ranged from 7 to 25 (mean ± SD, 11.3 ± 2.5) years. The compliance with wear and care behaviors was 19.7%, and the subjects' self-assessment compliance was 96.6%. The compliance rate of subjects wearing lenses for less than 1 year was higher than that of subjects wearing lenses for more than 1 year (p < 0.001). In the first year, the compliance rates of wearing experiences for less than 1 month, 1 month, 3 months, 6 months, and more than 6 months were 45, 29, 21.6, 20, and 27.6%, respectively, and there were no statistically significant differences in compliance among these periods (p = 0.314). No correlation was identified between compliance and age (r = - 0.061, p = 0.527) or sex (r = 0.114, p = 0. 751). There was no correlation between compliance and lens care operator (r = - 0.626, p = 0.151)., Conclusions: The compliance of ortho-k patients was poor. After wearing ortho-k lenses for more than 1 year, compliance with wear and care behaviors declined. In clinical practice, measures should be taken to solve these problems and improve the safety of wearing ortho-k lenses., (© 2021. The Author(s).)

Objective: To observe the possible changes in the integrity of the cornea and corneal endothelial cells of children/adolescents with low or moderate myopia after long-term wearing of orthokeratology (ortho-k) lenses, as well as the time when the relevant changes occur, so as to evaluate the safety of long-term wearing of ortho-k lens and to provide a reference for the safety evaluation of subjects wearing ortho-k lenses., Methods: Subjects were recruited in the Contact Lens Clinic, West China Hospital, Sichuan University for a three-year prospective study. Ortho-k of the same brand was matched for the subjects. The central corneal thickness (CCT), corneal endothelial cell density (ECD), and hexagonal cell ratio (HEX) were measured prior to the wearing of ortho-k lenses and after wearing ortho-k lenses for 1 month, 3 months, 6 months, and every 3 months until 36 months. The results of corneal fluorescence staining were recorded during each follow-up. When corneal staining was observed, the Efron grading standard was used for grading and corresponding treatment was given., Results: A total of 33 (66 eyes) myopic patients were included in the study. 15 cases (46.2%) reported having binocular foreign body sensations and tearing within the first week of wearing the lenses. After the subjects became adapted to wearing the lenses, the symptoms disappeared without intervention. During the follow-up period, 31 cases (93.94%) of binocular corneal staining were observed, of which, 24 cases (72.73%) were graded as G0, receiving no treatment, 5 cases (15.15%) were graded as GⅠ, and 2 cases (6.06%) were graded as GⅡ. Corresponding clinical treatment for corneal staining was given to the GⅠ and GⅡ subjects. This study found that the corneal ECD was inversely proportional to age ( r =－0.380, P =0.002). During the three-year follow-up period, the subjects' left eye ECD decreased from the baseline at 24 months and the right eye ECD decreased from the baseline at 27 months ( P <0.05). The CCT results in the subjects showed that CCT became thinner at 1 month after wearing the lens ( P <0.05), but the follow-up CCT showed a stable trend., Conclusion: After three years of long-term follow-up, no serious corneal complications occurred in children/adolescents with moderate and low myopia after long-term wearing of ortho-k lens. The corneal ECD of both eyes started decreasing 24 months after wearing the ortho-k lenses and the CCT decreased 1 month after wearing the lenses., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Purpose: To summarize the peer-reviewed literature on corneal structural changes after orthokeratology (OK) and to analyze the quality of the studies published., Methods: An exhaustive search was carried out in the databases Pubmed MEDLINE, Web of Science and Scopus. Original studies in English, with a cohort or experimental design and analyzing the cellular and structural changes of the cornea after OK fitting for myopia correction were selected. The NewCastle-Ottawa Assessment Scale (NOS) tool was used to analyze the quality of the studies selected., Results: The search provided a total of 1837 articles, of which 12 were selected following the inclusion and exclusion criteria. All studies had good quality according to the NOS tool (mean 7.58 ± 1.31). The mean ± standard deviation follow-up period of lens wear in the studies evaluated was 19.27 ± 33.97 months. The following reversible changes after OK have been reported: reduction in central epithelial basal cells, an increase in height and especially in width of superficial epithelial cells, as well as an increase in central stromal thickness and in the number of active keratocytes. Concerning corneal endothelium, only changes in terms of polymegathism were reported that were compatible with those observed for other types of contact lens wear. In relation to corneal sensitivity, there was a reduction during the use of OK, as well as in the nervous density of the sub-basal plexus at the central level, with some contradictory outcomes concerning the reversibility of these changes., Conclusion: OK produces reversible structural changes in the central epithelium and central anterior corneal stroma, as well as a decrease in the nerve density of the sub-basal plexus and corneal sensitivity. The quality of published studies evaluating these aspects is good, although more studies are needed to evaluate longer follow-up changes., (Copyright © 2020 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To present the 1-year results of the Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study, which aims to investigate the myopia control effect of orthokeratology (ortho-k) lenses with different back optic zone diameters (BOZD)., Method: Children, aged 6 to <11 years, having myopia -4.00 D to -0.75 D, were randomly assigned to wear ortho-k lenses with 6 mm (6-MM group) or 5 mm (5-MM group) BOZD. Data collection included changes in refraction, vision, lens performance and binding, ocular health conditions, axial length and characteristics of the treatment zone (TZ) area., Results: The 1-year results of 34 and 36 subjects (right eye only) in the 6-MM and 5-MM groups, respectively, are presented. No significant differences in baseline demographics were found between the groups (p > 0.05). The first-fit success rates, based on satisfactory centration at the 1-month visit, were 100% and 94% respectively. Horizontal TZ size was 0.92 mm and 0.72 mm smaller in the 5-MM group at the 6-month and 12-month visits, respectively (p < 0.05). At the 12-month visit, no significant between-group differences were found in the incidence of corneal staining (low grade only), lens binding and visual performance (all p > 0.05). Axial elongation was slower in the 5-MM group (0.04 ± 0.15 mm) than the 6-MM group (0.17 ± 0.13 mm) (p = 0.001). A significant positive correlation was observed between the horizontal TZ size and axial elongation (r = 0.36, p = 0.006)., Conclusion: Clinical performance of the two ortho-k lenses was similar, indicating that a smaller BOZD (5 mm) did not affect lens performance or ocular integrity. However, a smaller BOZD led to a reduced TZ, with retardation of axial elongation by 0.13 mm compared to conventional 6 mm BOZD ortho-k lenses after one year of lens wear., (© 2021 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Purpose: To evaluate thickness changes in the central and mid-peripheral cornea (CCT and mPCT), corneal epithelium (CET and mPET) and stroma (CST and mPST) of myopic children during and after short-term orthokeratology (ortho-k) lens wear, with conventional (CCF, 0.75 D) and increased compression factors (ICF, 1.75 D)., Methods: This was a self-controlled case series study. Subjects wore a CCF lens in one eye and an ICF lens in the other. Anterior segment optical coherence tomography images were captured weekly for 1 month during lens wear and for 2 weeks after discontinuing lens wear. CCT and CET (central 3-mm cornea) and mPCT and mPET (within a 4-6 mm diameter annulus) were measured. Stromal thickness (ST) was determined by subtracting epithelium thickness (ET) from corneal thickness (CT). The repeatability of the analytical software was also investigated on age-matched spectacle-wearing subjects (n = 98)., Results: Excluding three outliers (>3 S.D.s), the coefficient of repeatability and intraclass correlation coefficients of 98 spectacle-wearing subjects ranged from 2.63 to 4.64 μm and from 0.90 to 0.99, respectively. For the weekly-change study, CCT and CET in both eyes were significantly thinner after lens wear (p < 0.001) and CET thinning in the ICF eyes were significantly higher (p < 0.02). CCT changes were mainly contributed by CET. CST, mPCT, mPET and mPST changes were not significant (p > 0.20) in either eye. CT (all sublayers) rebounded to baseline values 2 weeks after discontinuing lens wear (0.99 > p > 0.12)., Conclusions: Significant reductions in CT and ET, but not ST, were observed within 1 month of ortho-k lens wear. Wearing ICF lenses resulted in a higher reduction in CET. Corneal thickness changes were reversible after discontinuing lens wear., (© 2021 The Authors Ophthalmic and Physiological Optics © 2021 The College of Optometrists.)

Purpose: To quantify the spatial distribution of relative corneal refractive power shift (RCRPS) to investigate its association with axial length growth., Methods: Eighty myopic children were randomly assigned for fitting with type A or B lenses. Axial lengths and corneal topographies were measured at baseline and the 1-, 6-, and 12-months follow-up visits. Treatment-zone decentrations and sizes were derived from tangential maps. RCRPSs were computed by taking the difference between after-treatment and baseline axial maps and then subtracting the apex value. Values at the same radius were averaged to obtain an RCRPS profile, from which four distributional parameters were extracted: the peak value (Rmax), the location where the profile first reached its half peak (X50), and the powers summed within 4- and 8-mm diameter areas (Sum4 and Sum8, respectively). Linear mixed models were used to analyse the correlation between the AL growth and the distributional parameters., Results: At baseline, no significant differences were observed between the two groups. After treatment, Axial length growth was significantly smaller in subjects fitted with type-B lenses (0.15 ± 0.16 vs 0.25 ± 0.22 mm, P = .028). Smaller treatment-zones (1.56 ± 0.14 vs 1.75 ± 0.13 mm, P < .01), smaller X50 values (1.56 ± 0.39 vs 1.98 ± 0.28 mm, P < .01), and greater Sum4 values (11.83 ± 6.47 vs 8.14 ± 5.06 D, P = .01) were also observed in subjects wearing type-B lenses. Among the distributional parameters, only X50 was significantly associated with AL growth in the multiple regression analysis ( P = .005)., Conclusion: The spatial distribution of RCRPS is critical in retarding AL growth, and the ones reaching peak within a shorter distance from the apex may provide better myopia control.

Orthokeratology (ortho-k) is the process of deliberately reshaping the anterior cornea by utilising specialty contact lenses to temporarily and reversibly reduce refractive error after lens removal. Modern ortho-k utilises reverse geometry lens designs, made with highly oxygen permeable rigid materials, worn overnight to reshape the anterior cornea and provide temporary correction of refractive error. More recently, ortho-k has been extensively used to slow the progression of myopia in children. This report reviews the practice of ortho-k, including its history, mechanisms of refractive and ocular changes, current use in the correction of myopia, astigmatism, hyperopia, and presbyopia, and standard of care. Suitable candidates for ortho-k are described, along with the fitting process, factors impacting success, and the potential options for using newer lens designs. Ocular changes associated with ortho-k, such as alterations in corneal thickness, development of microcysts, pigmented arcs, and fibrillary lines are reviewed. The safety of ortho-k is extensively reviewed, along with an overview of non-compliant behaviours and appropriate disinfection regimens. Finally, the role of ortho-k in myopia management for children is discussed in terms of efficacy, safety, and potential mechanisms of myopia control, including the impact of factors such as initial fitting age, baseline refractive error, the role of peripheral defocus, higher order aberrations, pupil size, and treatment zone size., (Copyright © 2021. Published by Elsevier Ltd.)

Acanthamoeba keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Contact lens use is the main risk factor for AK. The orthokeratology (OK) lens, a specially designed contact lens, has been used worldwide as an effective method of myopia control. However, the OK lens is associated with an increased risk of Acanthamoeba infection. Many primary practitioners are concerned about this infection because of its relative rarity, the lack of promising therapeutic medications, and the need for referral. We herein report two cases of AK associated with OK lenses, present a systematic review of such cases, and discuss the possible reasons for the higher incidence rate of this infection in patients who wear OK lenses. We combined the clinical knowledge and skills of corneal specialists and lens experts with the sole objective of addressing these OK lens-related AK cases. We found that the most common risk factors were rinsing the lenses or lens cases with tap water. Prompt and accurate diagnosis along with adequate amoebicidal treatment are essential to ensure desirable outcomes for OK lens wearers who develop AK. Appropriate OK lens parameters and regular checkups are also important.

Introduction: Recently in South Korea, there are increasing number of young adults undergoing orthokeratology treatment for myopia control. They prefer orthokeratology treatment more than wearing spectacles or having a refractive surgery for several reasons. However, there is little research on the effect of orthokeratology treatment on choroids., Objective: The aim of this study was to analyze the change in choroidal thickness (CT) in the horizontal axis in young myopic adults after orthokeratology treatment., Methods: This was a retrospective research among young myopic patients (-1.0 to -5.0 diopters) aged 19-29 years (n = 36; 23.6 ± 2.5 years). We selected patients who were treated with orthokeratology for 12 months. CT values of the horizontal axis near the fovea before and after orthokeratology treatment were analyzed using optical coherence tomography. The value was measured at the beginning of treatment and at 3, 6, and 12 months after orthokeratology treatment. Three regional areas of choroid on the horizontal plane including fovea were analyzed., Result and Conclusions: In the beginning of orthokeratology treatment, CT of the horizontal axis was 248.9 ± 45.7 μm in the temporal region, 259.9 ± 55.3 μm in the macular region, and 219.2 ± 46.4 μm in the nasal region. Three months after orthokeratology treatment, thickness values of choroids in the 3 divided areas increased significantly (p < 0.05). Mean CT at 6 or 12 months after orthokeratology treatment was greater than before ortho--keratology treatment. CT increased after 3 months of orthokeratology treatment in each regional area. In young myopic adults, CT in nasal area was thinner than that in foveal or temporal area before treatment. CT recovered to near baseline when it was observed for more than 6 months after orthokeratology treatment., (© 2020 S. Karger AG, Basel.)

Objective: To report the study design and one month's preliminary results of a randomized, single-masked, one-year prospective study of orthokeratology (ortho-k) in adults wearing lenses of different compression factors., Methods: Adults aged 18-38 years, with myopia of -0.75 to -5.00 D and astigmatism < 1.50 D, were recruited and randomly assigned into two groups: a conventional compression factor or Jessen Factor (CCF) group (compression factor = 0.75 D) and an increased (extra 1.00D) compression factor (ICF) group. Clinical outcomes, including spherical equivalent refraction (SER) reduction, visual acuity, corneal hysteresis (CH) and corneal resistance factor (CRF), and signs and symptoms were collected at the one-month follow-up visit. Indicators of the level of satisfaction and quality of life after commencing treatment were determined via a satisfaction questionnaire and the NEI-RQL-42 questionnaire., Results: Baseline data from 26 CCF and 24 ICF participants were analysed and no significant differences were observed between the two groups (p > 0.05). The first fit success rates were 90 % for CCF group and 83 % for the ICF group, SER reductions were 97 % and 95 % for the CCF and ICF group, respectively, with uncorrected high-contrast visual acuity of -0.06 (-0.18 to 0.42) and 0.00 (-0.16 to 0.52), respectively (p > 0.05) at the 1-month visit. Overall, the incidence of corneal staining was 77 % in the CCF and 79 % in ICF group; central corneal staining was 15 % and 33 %, respectively. However, the differences of corneal staining between the groups did not reach significance in any visit (p > 0.05). The main complaint from participants was glare (both groups). No significant differences in CRF and CH were found in the first month (p > 0.05). Both groups recorded high scores in the level of satisfaction questionnaire, with no significant differences between groups (p > 0.05). Compared with baseline scores, 1-month NEI-RQL-42 subscales of dependence on correction, appearance, and satisfaction with correction significantly increased, and the glare score significantly decreased in both groups (all p < 0.05)., Conclusions: The majority of participants were satisfied with the treatment and no serious corneal adverse effects were observed. These results demonstrate that ortho-k lenses of default and increased compression factor (1D) demonstrated similar clinical performance and ortho-k can be a safe and well-accepted option for myopia correction in adults, but long-term observation is warranted., (Copyright © 2020 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To determine the intensity of corneal pigmented arc in orthokeratology (ortho-k)-treated children and its correlation with wide epithelial thickness map (ETM) obtained through anterior segment optical coherent tomography (AS-OCT)., Methods: This retrospective case series reviews medical records of children who received ortho-k treatment for myopia control. Intensity of ortho-k-associated pigmented arc after wearing ortho-k lens more than 12 months and its correlation with each sector/zone of wide ETM obtained by AS-OCT was explored. Pigmented arcs were further divided into apparent and unapparent groups, and the clinical differences between groups were determined., Results: This study included 57 eyes of 29 children (mean age, 11.4 years, range 9-15); after initiating ortho-k treatment, the incidence of the corneal pigmented arc was 91.2% with mean lens wear duration of 26.1 months. Intensity of pigmented arc was significantly correlated with lens wear duration, target power, baseline degree of myopia, C zone and sectors I2, I3 and IT3 on wide ETM. Comparison between apparent and unapparent groups showed the same significant results except for C zone. After adjusting for lens wear duration and target power, sector I2 has the highest association with pigmented arc severity., Conclusion: Children treated with ortho-k are likely to develop ortho-k-associated pigmented arcs. The new wide ETM of AS-OCT can provide important information regarding the intensity of pigmented arc in these children. This can support customized pigmented arc-free ortho-k treatment for children in the future., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2020 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To evaluate the clinical effect of orthokeratology in controlling myopia and treating anisometropia among children with myopic anisometropia., Methods: A total of 108 myopic anisometropic children aged 8-16 years old who wore orthokeratology lenses in both eyes were enrolled in this study and followed up for over 1 year. The more severely myopic eye of each patient was assigned to the more myopic group (108 eyes), with a mean spherical equivalent refraction of -4.25 (-5.00, -3.38) D; the opposite eye of each patient was assigned to the less myopic group (108 eyes), with a refraction of -2.75 (-3.63, -1.88) D. This study observed and analyzed changes in ocular parameters after orthokeratology (Wilcoxon signed-rank test)., Results: In children who wore orthokeratology lenses for approximately 1 year, the level of anisometropia significantly dropped from 1.38 (1.13, 1.75) D to 1.25 (1.13, 1.75) D (P = .005). The difference between the axial lengths of the two eyes significantly dropped from 0.54 (0.37, 0.74) mm to 0.46 (0.28, 0.67) mm (P< .0001)., Conclusions: Orthokeratology seemed to be more effective at delaying the progression of myopia in the more myopic eyes than in the less myopic eyes of myopic anisometropic children. Orthokeratology lenses are suitable for anisometropic children, although the effectiveness of orthokeratology against anisometropia requires additional follow-up time for further observation and study., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest regarding the publication of this article., (Copyright © 2020 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Background: To investigate changes in the corneal thickness profile in juvenile myopia after overnight wear of orthokeratology lenses (OK)., Methods: A total of 53 juveniles (53 right eyes) successfully wore OK between January 2016 and July 2017 and they were reviewed one day, one week and one month after first wearing it. Epithelial and corneal data were obtained by optical coherence tomography (OCT). Changes in uncorrected visual acuity, refractive error, corneal refractive power, and epithelial and corneal thickness were analyzed before and after wear of OK., Results: The corneal epithelium was reshaped after 1 day of OK; the myopia degree was reduced, and uncorrected visual acuity reached 0 logMAR at 1 week. The central (2 mm) average epithelial thickness was 52.04 ± 2.35 μm, 49.25 ± 2.67 μm, 45.91 ± 2.80 μm, and 47.53 ± 3.44 μm before and after 1 day, 1 week, and 1 month of OK, respectively (t = 4.497, 9.741, and 7.340, respectively, P<0.001). The central epithelium was thinnest at 1 week, when the average thinning of 6.13 ± 1.67 μm accounted for approximately 11.78 % ± 3.21 % of the total epithelium thickness at baseline. The epithelial thickness of the reverse curve zone was 51.83 ± 2.49 μm, 57.62 ± 3.01 μm, 59.43 ± 3.19 μm, and 60.22 ± 2.75 μm before and after 1 day, 1 week, and 1 month of OK, respectively, showing a significant increase over time (t=-4.752, -6.208, and -6.848, respectively, P < 0.001)., Conclusion: In the early stage of OK, the corneal epithelium was redistributed very quickly. The central epithelium became thin, while the epithelium of the reverse curve zone correspondingly thickened. Effectively reduced the refractive power of the cornea equivalent to the effect of adding a concave spectacle lens, which ensures uncorrected vision after removal of the lenses., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose : To evaluate the relationship between magnitude of orthokeratology (OrthoK) treatment zone decentration and 2-year axial length (AL) elongation in myopic children. Methods : One-hundred and one Chinese children who wore OrthoK contact lenses for 2 years. The magnitude and direction of the OrthoK treatment zone center from the entrance pupil center were recorded after 3 and 24 months of lens wear along with AL measurement. Stepwise multiple linear regression analysis was performed to assess which factors significantly affected an increase in AL. Results : After 3 and 24 months of OrthoK treatment, the mean (± standard deviation [SD]) magnitude of the OrthoK treatment zone decentration was 0.64 ± 0.38 mm and 0.68 ± 0.32 mm, respectively. There were no significant differences between the two time points ( P > .05). After 2 years of OrthoK contact lenses wear, the mean (± SD) AL growth was 0.36 ± 0.34 mm. The axial elongation was slightly correlated with baseline age of subjects (r = -0.073, P < .001), baseline spherical equivalent refractive error (r = -0.088, P < .001) and magnitude decentration of treatment zone (r = -0.190, P = .027). Conclusions : The decentration of OrthoK treatment zone stabilizes after 3 months of lens wear and slightly decreases AL growth.

Purpose: To evaluate the risk factors associated with contamination of lens cases in a group of orthokeratology (ortho-k) lens wearers., Method: Ortho-k patients attending the Contact Lens Clinic of the Hospital were required to complete a checklist about their routine daily care and handling of lens cases. Their cases were then collected for analysis. Contamination was evaluated by determining the optical density (OD) of crystal violet stained biofilm present in the cases. OD values were divided into three groups, lower, middle, and upper tertiles, and associations between risk factors were determined by multivariate analysis., Results: A total of 194 subjects were recruited. Twenty-five subjects used cylindrical lens cases (CC), 98 flat cases with ridges (FCR), and 71 flat cases without ridges (FC). FCRs were the most heavily contaminated and CC showed least contamination (FCR > FC, OR 2.16, CI 1.11-4.18, p =  0.023; FCR > CC, OR 8.86, CI 2.97-26.44, p <0.001; FC > CC, OR 2.33, CI 1.35-12.45, p =  0.013). Replacing lens cases monthly significantly reduced the risk of high contamination (OR 0.013, CI 0.06-0.30, p <  0.001), compared to those used for three months. Cases that were not rinsed (OR 3.44, CI 1.50-7.86, p =  0.003) or rinsed by other methods (OR 4.07, CI 1.67-9.92, p =  0.002) had significantly more contamination, compared to those rinsed with multipurpose solution. Lens cases, which were not dried (OR 11.36, CI 2.06-62.93, p =  0.005) or air-dried (OR 8.71, CI 1.16-65.56, p =  0.036), showed more contamination compared to those wiped with tissue daily., Conclusion: Case design (cylindrical), monthly replacement, daily rinsing with MPS, and wiping with tissue daily can effectively reduce biofilm formation in contact lens cases., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose : To measure changes in visual performances and optical quality in myopic children during the first month of wearing orthokeratology lens, and to reveal the association between those two. Methods : Thirty-five myopic children participated in this study. Visual performances were evaluated with visual acuity and shape discrimination threshold (SDT) for radial frequency patterns. Placido disc-based corneal topography for central 4 mm and 6 mm zones was collected and decomposed by Fourier analysis into the spherical, asymmetric, and regular astigmatic components. Root-mean-square of third-order, fourth-order, and total higher-order aberrations (HOA) were extracted for the 4 mm and 6 mm zones. All examinations were conducted at baseline, 1-week, and 1-month after lens dispensing. The changing trends over time and association between SDT and optical quality were analysed with linear-mixed model. Results : All subjects' uncorrected visual acuity improved to 0.1 logMAR or better at 1-week and 1-month lens wear ( P < .01). SDT did not change significantly from the baseline at 1-week and 1-month after lens wear ( P > .05). For the two zones with diameters of 4 mm and 6 mm, the spherical component decreased significantly at 1-week ( P < .01) and remained stable thereafter ( P < .01); the asymmetric component increased significantly at 1-week ( P < .01) and remained high at 1-month ( P < .01); and the regular astigmatism did not show any significant change throughout ( P > .05). At the two zones with diameters of 4 mm and 6 mm, the third-order, fourth-order, and total HOA increased significantly over time ( P < .05). Change of SDT did not correlate with impairments in optical quality ( P > .05 for all parameters). Conclusions : While corneal optical quality decreased steadily during the first month following lens wearing, the visual acuity and shape discrimination sensitivity assessed by SDT remained very satisfactory.

Purpose: To determine whether orthokeratology (OK) induced treatment zone (TZ) diameter can be reduced by altering OK lens design, and if so the impact of modifying TZ diameter on relative peripheral refraction (RPR)., Methods: 16 subjects (mean age 23.4 ± 1.5 years; 8 female) completed the study. Standard (Control) OK lens design (PJ, Capricornia, Australia) or a modified version (Test) where the back optic zone diameter was reduced, and back optic zone asphericity and intermediate lens curves were altered, were worn overnight only for 7-nights in a randomised double masked order, with a minimum 1-week wash out (no lens wear) between lens designs. Full correction of refractive error was targeted. Refraction; best corrected visual acuity (BCVA); RPR (Shin-Nippon NVision-k 5001) along the horizontal and vertical meridians; and corneal topography (Medmont E300) were measured before starting lens wear and in the morning after lens removal after the seventh night of lens wear for both lens designs. TZ diameter and decentration was calculated from corneal topography., Results: After 7-nights of wear both lens designs created -2.00D refraction effect with no significant difference in refractive effect or change to BCVA between the designs. The Test design created a significantly smaller horizontal (4.78 ± 0.37 vs 5.70 ± 0.37 mm, p < 0.001) and vertical (5.09 ± 0.51 vs 5.92 ± 0.51 mm p < 0.001) TZ diameter. The TZ was decentered inferior temporal with no significant difference between designs. There was no significant difference between the lens designs in RPR along the horizontal and vertical meridians at any measurement period., Conclusions: OK induced TZ diameter can be reliably reduced by altering OK lens design without detrimentally effecting lens centration or refractive effect. Reducing TZ diameter did not alter RPR, though measurement artifacts could be responsible for masking an effect. Longitudinal studies are needed to assess whether smaller TZ OK lens designs increase efficacy for slowing progression of myopia., (Copyright © 2019. Published by Elsevier Ltd.)

Purpose: To evaluate changes in refractive and corneal responses in myopic children wearing orthokeratology (ortho-k) lenses with conventional compression factor (CCF, 0.75 D) and increased compression factor (ICF, 1.75 D)., Methods: This was a double-blind self-controlled study. Subjects were randomly fitted with CCF in one eye and ICF in the fellow eye. Weekly monitoring of refraction, visual acuity (VA), external ocular health, and corneal responses were performed over one month of lens wear and after discontinuation of lens wear until stabilization was achieved., Results: Twenty-five subjects, aged 9.4 ± 1.0 years, completed one-month lens wear, of whom 23 completed the washout period. The first fit success rates for CCF and ICF were 93% and 96%, respectively. Myopia, unaided VA, central corneal thickness, anterior corneal curvatures (K), apical power (AP), and corneal resistance factor (CRF) all changed significantly during the study period (P <  0.003). Between-eye difference was significant only for myopia reduction (P =  0.001). About 4% and 8% of ICF and CCF eyes were under-corrected. The attempted target was achieved in about 80% of CCF and 60% of ICF eyes at week 4. At the end of the washout period (3 weeks), myopia, K, and AP were significantly different compared to baseline (P <  0.001)., Conclusion: Increasing the compression factor did not affect the first fit success rate and external ocular health, but did allow faster correction of refractive error within one month of lens wear. Further investigation is warranted to investigate the long-term effects of ICF on myopia control compared to CCF., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To investigate the effect of overnight orthokeratology (OK) lens wear on axial growth in anisometropic children., Methods: The study involved 17 males and 12 females with an average age of 11.4 ± 2.9 years. Cycloplegic spherical equivalent error (SER) was -0.50D to -6.00D, and anisometropia ≥1.00D. The eyes with greater myopia were assigned to the G eye group and the fellow eyes with less myopia to the L eye group. All eyes were fitted with OK lenses. Axial length (AL) was measured at the beginning of the study and at 6-, 12-, 18-, and 24-month follow-up visits. Refractive error was measured at the beginning and at the 24-month visit. Linear mixed model analysis was used to evaluate the effect of time, group, and time*group on axial growth. Paired t test was used to compare the myopia increase over 24 months between the two groups., Results: The mean baseline AL was 25.06 ± 0.61 mm for the G eyes and 24.48 ± 0.61 mm for the L eyes. After 24 months, AL had increased by 0.31 ± 0.23 mm in the G eye group and by 0.41 ± 0.31 mm in the L eye group. Axial growth of the L eyes was significantly greater than that of the G eyes (p = 0.006). The mean baseline myopia of the G eye and the L eye was -3.62 ± 1.27D [-5.75D to -1.75D] and -1.93 ± 1.02D [-4.00D to -0.50D] respectively. At 24 months, the increase in myopia in the G eyes was significantly less than that in the L eyes (-0.84 ± 0.63D vs, -1.21 ± 0.89D, p < 0.001)., Conclusions: In anisometropic children who wore OK lenses, axial growth was greater in the eye with less baseline myopia than in the fellow eye with greater baseline myopia after 2 years., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To report a case of reduced aniseikonia in a myopic axial anisometrope during orthokeratology (OK) lens wear., Case Report: A 19-year-old female university student with myopic anisometropia presented for an OK lens fitting consultation. At baseline, perceptual interocular image size difference or aniseikonia of 1.45% was found, with a smaller image seen by the right eye compared to the left eye. The patient was fitted with a pair of OK lenses and interocular image size differences, subjective refraction and corneal topography were measured after 7, 14 and 47 days of overnight lens wear. Hyperopic shifts in central refraction and corresponding flattening of the central cornea was measured during OK treatment. Aniseikonia reduced after OK wear with the most significant change measured from baseline to day 7. Aniseikonia recorded after 7, 14 and 47 nights of lens wear was 0.05%, 0.35% and 0.85%, respectively. Although minimum differences in refractive error between eyes was reached after 47 days of OK, aniseikonia was greater than that measured after 7 and 14 days of OK., Conclusion: This case report demonstrates reduction in aniseikonia with OK lens wear in a myopic patient with axial anisometropia, although this effect was not sustained beyond 1 week of lens wear. As the impact of corneal curvature changes on aniseikonia is not well understood, future studies on the impact of OK on aniseikonia and associated asthenopia is required., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: To compare axial length (AL) elongation in myopic children with four Orthokeratology (OrthoK) lenses and spectacles., Methods: The medical records of 266 patients (532 eyes) who were fitted with OrthoK lenses or spectacles (control group) were reviewed. Data collection included baseline age, gender, baseline objective sphere and cylinder, baseline flat and steep corneal meridian power, corneal asphericity coefficient (Q value), AL at baseline and after 1-year, and 2-years of OrthoK or spectacle wear analyzed using analysis of repeated measures data ANOVA. Stepwise linear regressions between the changes in AL after 2 years relative to baseline parameters were calculated for the OrthoK and control groups separately., Results: The baseline subject parameters for each of the four OrthoK lenses were not statistically different. Statistically significant differences between time points were found between 12- and 24- months (all P < 0.05). AL growth was slower in all OrthoK groups than in the control group (all P < 0.05). AL grew 0.081±0.034 mm per year slightly less than average with Essence compared to the Mouldway OrthoK group (P = 0.019). The coefficient of regression weakly expressed between the increases in AL over 2-years study period and baseline spherical equivalent refraction was 0.065 in Essence, 0.079 in Euclid and 0.087 in Mouldway. The coefficient of regression was also weakly between age and the increases AL over 2-years study period and baseline age in all groups., Conclusion: Different OrthoK lenses differ minimally in slowing axial elongation effectively in myopic children during 2-years lens wear., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Background: To investigate the influence of compression factor upon changes in ocular higher-order aberrations (HOAs) in young myopic children undergoing orthokeratology treatment., Methods: Subjects aged between six and < 11 years, with low myopia (0.50-4.00 D inclusive), low astigmatism (≤ 1.25 D), and anisometropia (≤ 1.00 D), were randomly assigned to wear orthokeratology lenses of different compression factors in each eye (one eye 0.75 D and the fellow eye 1.75 D). HOAs were measured weekly over one month of lens wear. Wavefront analysis was conducted over a 5-mm pupil using a sixth order Zernike polynomial expansion. Linear mixed models were used to examine the individual Zernike co-efficients and specific root-mean-square (RMS) error (spherical, comatic, total HOAs) metrics and their changes between the two eyes during the study period., Results: Twenty-eight myopic (mean manifest spherical equivalent refraction: -2.10 ± 0.58 D) children (median [range] age: 9.3 [7.8-11.0] years) were analysed. Significant interocular differences in HOAs at baseline were observed for Z 6 - 6 and Z 6 - 4 only (both p < 0.05). During the lens wear period, eyes fitted with the increased compression factor showed greater changes in primary spherical aberration ( Z 4 0 , p = 0.04) and RMS values for spherical and total HOAs (both p < 0.01). Considering data from both eyes together, after adjusting for the paired nature of the data, some other Zernike terms ( Z 3 1 and Z 6 0 , both p < 0.01) and the RMS value of comatic aberrations (p < 0.001) significantly increased after one month of orthokeratology treatment. The increase in primary spherical aberration ( Z 4 0 ) was positively correlated with the reduction in spherical equivalent refractive error, but only in eyes fitted with the increased compression factor (r = 0.69, p < 0.001)., Conclusions: Increasing the orthokeratology compression factor by 1.00 D significantly altered some HOAs, particularly spherical aberration. Given the association between positive spherical aberration and eye growth in children, further research investigating the influence of orthokeratology compression factor on axial eye growth is warranted., (© 2019 Optometry Australia.)