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

BACKGROUND: To evaluate the long-term effectiveness of orthokeratology (ortho-K) lenses with small treatment zone (STZ) or conventional treatment zone (CTZ) in controlling axial elongation in children with myopia as well as the impact on visual quality. We also sought to determine the effect of retinal visual signal quality on axial elongation. METHODS: This is a prospective randomized controlled study. A total of 140 participants (age ranging from 8 to 12 years) were randomly assigned to wear either STZ or CTZ ortho-K lenses. STZ ortho-K lenses design was achieved by changing the depth of reverse zone and the sagitta height of the optical zone. Using the IOL-Master 500, axial length (AL) was measured at baseline and after 6, 12 and 18 months of ortho-K treatment. Spherical aberration (SA) and corneal topographic parameters were obtained by the Pentacam anterior segment analyzer at baseline and the 1-month follow-up visit, and optical qualities were assessed by optical quality analysis system-II (OQAS-II) at baseline and after 1 month of lens wearing. Optical quality parameters mainly included the modulation transfer function (MTF) cutoff, Strehl ratio (SR), objective scattering index (OSI), and predicted visual acuity (PVA). RESULTS: A total of 131 participants completed the study, including 68 in the STZ group and 63 in the CTZ group. The STZ group had significantly reduced AL elongation compared to the CTZ group after treatment (12 months: 0.07 ± 0.11 mm vs. 0.14 ± 0.12 mm, P = 0.002; 18 months: 0.17 ± 0.15 mm vs. 0.26 ± 0.16 mm, P = 0.002). The topography in the STZ group showed a smaller treatment zone (TZ) diameter (2.50 ± 0.23 mm vs. 2.77 ± 0.18 mm, P < 0.001), a wider defocus ring width (2.45 ± 0.28 mm vs. 2.30 ± 0.30 mm, P = 0.006), and larger values of total amount of defocus (119.38 ± 63.71 D·mm2 vs. 91.40 ± 40.83 D·mm2, P = 0.003) and total SA (0.37 ± 0.25 µm vs. 0.25 ± 0.29 µm, P = 0.015), compared with the CTZ group. Objective visual quality decreased in both groups (P < 0.001). This was evidenced by a greater decrease in MTF cutoff (- 14.24 ± 10.48 vs. - 10.74 ± 9.46, P = 0.047) and SR values (- 0.09 ± 0.07 vs. - 0.06 ± 0.07, P = 0.026), and an increase in OSI value (0.84 ± 0.72 vs. 0.58 ± 0.53, P = 0.019). PVA9% decreased significantly in the STZ group but not the CTZ group. A statistically significant negative correlation was found between the changes in total SA and MTF cutoff values (r = - 0.202, P = 0.025). AL changes were associated with sex, change of MTF cutoff value, increment of total SA and TZ area. CONCLUSIONS: Compared with CTZ ortho-K lenses, STZ ortho-K lenses significantly inhibited axial elongation in children with myopia while moderately reducing their objective visual quality. Axial elongation was affected by retinal visual quality, and it may be a possible mechanism for ortho-K slowing myopia progression. Trial registration This trial is registered at Chinese Clinical Trial Registry on November 5, 2019 with trial registration number: ChiCTR1900027218. https://www.chictr.org.cn/showproj.html?proj=45380.

Clinical Features and Visual Outcome of Infectious Keratitis Associated with Orthokeratology Lens in Korean Pediatric Patients.

Purpose: To investigate the clinical features and visual outcome of infectious keratitis associated with Orthokeratology (Ortho-K) lens in Korean pediatric patients. Methods: We retrospectively reviewed medical records of patients diagnosed with Ortho-K lens-associated infectious keratitis from June 2005 to April 2020 at a tertiary referral hospital. Patients' demographics, clinical features, microbiological evaluation, and treatment methods were assessed and factors related to final visual outcomes were analyzed. Results: The study included 26 eyes of 26 patients (19 female, 7 male; mean age: 11.9 years), with an average Ortho-K lens wear duration of 33.7 ± 21.2 months. The highest number of cases occurred in summer (42.3%, 11/26). Central or paracentral corneal lesions were observed in 96.2% (25/26) of cases, with a mean corneal epithelial defect size of 5.13 mm². Pseudomonas aeruginosa was the most commonly isolated organism (n = 5), followed by Serratia marcescens (n = 4). All patients responded to medical treatment without needing surgical intervention. 72% of cases achieved favorable visual outcomes (Snellen BCVA > 6/12), while 8% experienced severe visual impairment (Snellen BCVA ≤ 6/60) due to residual central corneal opacities. Multivariable analysis showed that non-summer seasons, duration from symptom onset to presentation, and corneal epithelial defect size were significantly associated with final logMAR BCVA (p = 0.043, p = 0.040, and p = 0.002, respectively). Failed autorefraction at presentation due to an Ortho-K-related infectious keratitis lesion was a significant predictor of poor final visual outcome (Snellen BCVA ≤ 6/12) (OR = 38.995, p = 0.030). Conclusions: Ortho-K lens-related infectious keratitis can lead to permanent corneal opacities and potentially devastating visual outcomes in children. Delayed time to presentation, large corneal lesions, failure of autorefraction, and non-summer seasons were associated with poorer outcomes. Proper education and early detection would be key to safe use of orthokeratology lenses in pediatric patients.

Development and evaluation of a deep neural network model for orthokeratology lens fitting.

PURPOSE: To optimise the precision and efficacy of orthokeratology, this investigation evaluated a deep neural network (DNN) model for lens fitting. The objective was to refine the standardisation of fitting procedures and curtail subjective evaluations, thereby augmenting patient safety in the context of increasing global myopia. METHODS: A retrospective study of successful orthokeratology treatment was conducted on 266 patients, with 449 eyes being analysed. A DNN model with an 80%-20% training-validation split predicted lens parameters (curvature, power and diameter) using corneal topography and refractive indices. The model featured two hidden layers for precision. RESULTS: The DNN model achieved mean absolute errors of 0.21 D for alignment curvature (AC), 0.19 D for target power (TP) and 0.02 mm for lens diameter (LD), with R2 values of 0.97, 0.95 and 0.91, respectively. Accuracy decreased for myopia of less than 1.00 D, astigmatism exceeding 2.00 D and corneal curvatures >45.00 D. Approximately, 2% of cases with unique physiological characteristics showed notable prediction variances. CONCLUSION: While exhibiting high accuracy, the DNN model's limitations in specifying myopia, cylinder power and corneal curvature cases highlight the need for algorithmic refinement and clinical validation in orthokeratology practice.

The corneal biomechanical differences after wearing orthokeratology lenses and multifocal soft lenses in children: A self-control study.

BACKGROUND: To compare the changes in corneal biomechanics after orthokeratology (OK) lens and Defocus Incorporated Soft Contact (DISC) lens treatment. METHODS: Of 28 myopic children were recruited, with one eye wearing OK lens and the other eye wearing DISC lens for one year, and the data after discontinued for 4 weeks were also collected. Major outcomes were corneal biomechanics and axial length (AL) elongation. RESULTS: Throughout the follow-up period, the DISC group had longer the first applanation (A1) time, larger A1 deformation amplitude, A1 deflection length (A1 DLL), and A1 deflection amplitude than the OK group. AL elongation was less in the OK group at each visit (all P < 0.05) but faster in the OK group than in the DISC group after discontinuation (P = 0.006). Moreover, AL elongation was related to baseline A1 time, A1 velocity and whole eye movement max in the DISC group, and in the OK group, was related to the baseline the second applanation (A2) DLL, A2 delta arc length and stiffness parameter A1 (all P < 0.05). CONCLUSIONS: The cornea was more deformable after wearing DISC lens than OK lens, and corneal biomechanical parameters were associated with AL elongation. Eyes showed less AL elongation during OK lens treatment while faster AL elongation after discontinuation than DISC lens. The baseline corneal biomechanics may help to predict AL elongation in myopic control strategies.

Influence of orthokeratology lens decentration on periretinal defocus in my-opic eyes / 眼科新进展

Objective To investigate the effect of orthokeratology(OK)lens decentration on peripheral retinal defo-cus in myopic eyes.Methods Totally 154 patients(234 eyes)continuously wearing OK lenses for one month or more were recruited in this study.According to the location of defocus rings in corneal topography,these eyes were divided into the centration group(118 eyes)and the decentration group(116 eyes).Peripheral retinal defocus data of each patient was collected by multispectral refraction topography,including total refraction difference value(TRDV),refraction difference value at 15°(RDV-15),refraction difference value at 30°(RDV-30),refraction difference value at 45°(RDV-45),superior refraction difference value(RDV-S),inferior refraction difference value(RDV-I),temporal refraction difference value(RDV-T)and nasal refraction difference value(RDV-N).An independent sample t-test was used to compare the differ-ences in these parameters between the two groups,and multivariate correlation analysis(generalized estimating equation,GEE)was conducted to analyze the relationship between clinical parameters and the amount of peripheral retinal defocus within the group.Results The RDV-N of patients in the decentration group was significantly lower than that in the cen-tration group(t=2.668,P=0.008),and there were no significant differences in other parameters(all P＞0.05).GEE showed that age was the determinant of RDV-S,and they were positively correlated;steep K was the determinant of RDV-I,and they were negatively correlated;gender was the determinant of RDV-T,and female OK lens wearers showed less RDV-T;the determinants of RDV-N include the alignment of OK lens,eye distribution and age,among which,RDV-N was positively corrected with age,and RDV-N of the left eyes was significantly superior to that of the right eyes.Conclusion Subclinical decentration of the OK lens may result in better RDV-N of myopia patients.The peripheral retinal defocus is influenced by factors such as age,gender,steep K,amount of decentration and eye distribution of OK lens wearers.

Meta-analysis of the myopia control effect of orthokeratology lenses with dif-ferent back optical zone diameters / 眼科新进展

Objective To systematically evaluate the changes in axial length and treatment zone diameter among my-opic patients wearing orthokeratology lenses with different back optic zone diameters.Methods A comprehensive litera-ture search was conducted on PubMed,Embase,the Cochrane Library,Web of Science,Wangfang Med Online and CNKI databases in both Chinese and English to identify randomized controlled trials or controlled trials investigating orthokeratol-ogy lenses with varying back optical zone diameters.The literature was thoroughly reviewed by two researchers,who ex-tracted relevant data and conducted a methodological quality evaluation.Finally,meta-analysis was performed using Rev-Man 5.3 software.In all the included studies,orthokeratology lenses with a conventional back optic zone diameter were taken as the control group,while orthokeratology lenses with a reduced back optic zone diameter were utilized as the ex-perimental group.Results Eight studies involving 437 patients(459 eyes)with myopia were included.The results of me-ta-analysis showed that the axial length changes in the experimental group were significantly lower than those of the control group after wearing orthokeratology lenses for 6 months and 12 months(6 months:MD=-0.09,95％CI:-0.10 to-0.07,Z=10.50,P＜0.05;12 months:MD=-0.11,95％CI:-0.13 to-0.09,Z=12.19,P＜0.05);significant differ-ences in treatment zone diameter were observed between the experimental and control groups at various time points follow-ing orthokeratology lens wearing(MD=-0.82,95％CI:-1.04 to-0.59,Z=7.03,P＜0.05).Conclusion Orthoker-atology lenses designed with smaller back optical zone diameters can effectively delay axial length growth in myopic pa-tients,but their long-term efficacy needs to be confirmed.

Role of spherical aberration and coma in orthokeratology for myopia control / 国际眼科杂志(Guoji Yanke Zazhi)

As a highly prevalent global condition, myopia significantly impacts the ocular health of young individuals in China. Orthokeratology lens, as a rigid corneal contact lens, has demonstrated effective control over the progression of myopia; however, its mechanism of action remains incompletely elucidated. As one of the factors influencing visual acuity, higher-order aberrations will undergo marked changes after orthokeratology, with particular emphasis on the alterations in spherical aberrations and coma. The changes in corneal morphology induced by orthokeratology lead to significant positive increase in both spherical aberration and coma. Furthermore, the elevation of spherical aberration and coma demonstrates a negative correlation with the rate of axial length growth following orthokeratology. The interplay among spherical aberration, coma, defocus, accommodation, astigmatism, and pseudo-accommodation may constitute the underlying mechanism governing the control of myopia through orthokeratology.

Feasibility and ethnic differences of 0.005% atropine eye drops combined with orthokeratology in controlling low myopia in adolescents / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To observe the effectiveness, safety and ethnic differences of 0.005% atropine eye drops combined with orthokeratology in controlling adolescents' low myopia between different ethnic groups.METHODS:A total of 246 Han and Hani patients(246 eyes)with low myopia treated in our hospital from January to October 2021 were selected, with 120 patients(120 eyes)treated with 0.005% atropine eye drops combined with orthokeratology in experimental group, and 126 patients(126 eyes)treated with orthokeratology in control group. The uncorrected visual acuity, spherical equivalent(SE), axial length(AL), intraocular pressure, tear film break-up time(BUT), corneal curvature and corneal thickness of the two groups before and 1 a after wearing lenses were observed, and the incidence of complications were recorded.RESULTS:At 1 a after wearing lenses, the changes of AL and SE in the experimental group(0.16±0.35 mm, -0.39±0.47 D)were lower than those in the control group(0.22±0.89 mm, -0.48±0.54 D), uncorrected visual acuity(LogMAR)was better than the control group(0.11±0.25 vs 0.14±0.19; P&#x0026;#x003C;0.05), there were differences in BUT, anterior chamber depth, corneal curvature and corneal thickness(P&#x0026;#x003C;0.05), but there were no differences in intraocular pressure of the two groups(P&#x0026;#x003E;0.05). In the Han and Hani groups, there were no differences in the changes of uncorrected visual acuity, AL and SE(P&#x0026;#x003E;0.05). During the follow-up period, no significant local or systemic adverse reactions occurred in the two groups, and there was no difference in the incidence of ocular complications between the two groups of patients(P&#x0026;#x003E;0.05).CONCLUSION: The 0.005% atropine eye drops combined with orthokeratology can effectively delay the progression of low myopia in adolescents without significant adverse reactions and ethnic differences.

Comparison of the control effect of corneal refractive therapy with vision shaping treatment designed orthokeratology on corneal morphology myopia at low E-values / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To observe and analyze the effectiveness and safety of wearing corneal refractive therapy(CRT)and vision shaping treatment(VST)designed orthokeratology in controlling myopic progression in adolescents with low E-value corneal morphology.METHODS: This prospective study involved 100 cases(100 eyes)of adolescent myopia patients fitted with orthokeratology at our optometry clinic from January 2020 to December 2021. The data of right eye were collected for research, and they were divided into low myopia group(-1.00 to -3.00 D)and moderate myopia group(-3.25 to -5.00 D)according to spherical equivalent, with 50 cases in each group. Each group of patients was further randomly divided into the CRT group and the VST group, with 25 cases in each group. Uncorrected visual acuity, refractive error, axial length(AL), tear film break-up time(BUT), corneal endothelial cell density, corneal staining grading, lens decentration, and refractive power at 15°-30° were measured before and after wearing orthokeratology, with a follow-up duration of 1.5 a.RESULTS: The uncorrected visual acuity of CRT and VST subgroups in the low myopia group showed no statistical significance at any time point after wearing orthokeratology. However, in the moderate myopia group, CRT subgroup showed better uncorrected visual acuity than the VST subgroup, with significant differences at 1 d and 1 wk(t=-9.474, -12.067, both P&#x003C;0.01); no significant differences were noted at other time points. After wearing lens for 6 mo and 1.5 a, the AL growth for the CRT subgroup in low and moderate myopia was less than the VST subgroup, with no statistically significant differences. There were no statistically significant differences in binocular BUT and corneal endothelial cell density after wearing lens for 6 mo and 1.5 a. Corneal injury was lower in the CRT subgroup than that in the VST subgroup, but the difference was not statistically significant(Z=-1.803, P=0.071). Lens decentration was significantly better in the CRT subgroup than in the VST subgroup(Z=-4.629, P&#x003C;0.001). In the periphery of the retina at 15°-30°, there were no significant differences in the amount of myopic defocus between the two groups, while it was statistically significant at 1, 3, and 6 mo in the moderate myopia subgroup(t=-3.949, P=0.008; t=-5.833, P&#x003C;0.001; t=-6.231, P&#x003C;0.001), indicating that CRT subgroup could produce a greater amount of myopic defocus.CONCLUSION: For patients with low E-value corneal morphology, CRT, using the vector height at 8 mm on the cornea for fitting, is not limited to the corneal E-value. It shapes faster and improves uncorrected visual acuity after shaping, especially for moderate myopia, achieving better daytime vision. In terms of controlling myopia, CRT fitting elevates return zone depth(RZD), creating a small central optical zone to produce more peripheral myopic defocus. However, there was no significant difference between the two groups in controlling AL growth. Both groups showed minimal corneal damage, indicating consistent safety in myopia control.

Analysis of the effect and safety of orthokeratology lens on myopia control in adolescents and children with different diopters / 中国现代医生

Objective To investigate the effect and safety of orthokeratology lens on myopia control in adolescents and children with different diopters.Methods Ninety-three patients(171 eyes)with myopia who received orthokeratology lens treatment in the Affiliated Jiangning Hospital of Nanjing Medical University from February to August 2021 were selected for the study.They were divided into a low degree group(88 eyes,-0.5D to-3.0D)and medium degree group(83 eyes,-3.0D to-6.0D)according to the equivalent spherical lens degree.The naked eye distant vision,diopter,optic axis,breakup time of tear film(BUT),corneal endothelial cell count and complications were compared between two groups.Results After 1 year of lens wear,growth of optic axis in low degree group was significantly greater than that in medium degree group(Z=-2.035,P=0.042).After 1 year of lens wear,naked eye distant vision of both groups was significantly higher than that before lens wear(P<0.05),and increase of visual acuity in medium degree group was significantly greater than that in low degree group(P<0.05).The equivalent spherical degree of two groups was significantly lower than that before lens wear(P<0.05),and reduction of equivalent spherical lens degree in medium degree group was significantly greater than that in low degree group(P<0.05).After 1 year of lens wear,BUT in both groups was significantly shorter than that before lens wear,and corneal endothelial cell count was lower than that before lens wear(P<0.05),but there were no significant differences in BUT and corneal endothelial cell count between two groups(P>0.05).There was no statistically significant difference in complication rate between two groups(χ2=2.000,P=0.157).Conclusion Orthokeratology lens has good control effect and safety for adolescents and children with different diopters,and the effect is more prominent for moderate myopia.

Changes in axial length in anisometropic children wearing orthokeratology lenses.

Purpose: There is a particular anisometropia occurring in one eye with myopia, while the other eye has very low myopia, emmetropia, or very low hyperopia. It is unclear how the binocular axial length changes when these children wear unilateral OK lenses only in the more myopic eyes. This study investigates the changes in the axial elongation of both eyes. Methods: This is a 1-year retrospective study. In total, 148 children with myopic anisometropia were included. The more myopic eyes were wearing orthokeratology lenses (treated eyes), whereas the contralateral eyes were not indicated for visual correction (untreated eyes). The untreated eyes were classified into three subgroups based on the spherical equivalent refraction (SER): low myopia (≤ -0.50 D, n = 37), emmetropia (+0.49 to -0.49 D, n = 76), and low hyperopia (≥0.50 D, n = 35). Changes in the axial length (AL) were compared between the untreated and treated eyes and among the three subgroups. Results: The axial elongation was 0.14 ± 0.18 mm and 0.39 ± 0.27 mm in all treated and untreated eyes, respectively (p < 0.001). The interocular AL difference decreased significantly from 1.09 ± 0.45 mm at the baseline to 0.84 ± 0.52 mm at 1 year (p < 0.001). The baseline median (Q1, Q3) SER of the untreated eyes were -0.75 D (-0.56, -0.88 D), 0.00 D (0.00, -0.25 D), and +0.75 D (+1.00, +0.62 D) in low myopia, emmetropia, and low hyperopia subgroups, respectively. The axial elongation was 0.14 ± 0.18 mm, 0.15 ± 0.17 mm, and 0.13 ± 0.21 mm (p = 0.92) in the treated eyes and 0.44 ± 0.25 mm, 0.35 ± 0.24 mm, and 0.41 ± 0.33 mm in the untreated eyes (p = 0.11) after 1 year. Multivariate linear regression analyses only showed significant differences in axial elongation between the emmetropia and low myopia subgroups of untreated eyes (p = 0.04; p > 0.05 between other subgroups). Conclusion: Unilateral orthokeratology lenses effectively reduced axial elongation in the more myopic eyes and reduced interocular AL differences in children with myopic anisometropia. The refractive state of the untreated eyes did not affect the axial elongation of the more myopic eye wearing the orthokeratology lens. In the untreated eyes, AL increased faster in the low myopia subgroup than in the emmetropia subgroup.

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

PURPOSE: To compare the effect of orthokeratology (ortho-k) using aspheric or spherical base curve (BCA vs. BCS) contact lenses on axial elongation and the relative peripheral refraction change (RPRC) in Chinese children. METHODS: Children aged 8-12 years with myopia between -0.75 and -4.00 D and astigmatism ≤1.00 D were randomly assigned to the BCA or BCS group. Peripheral refraction was assessed at 10°, 20° and 30° along the temporal and nasal retina at baseline and at the 12-month visit. Axial length (AL) was measured under cycloplegia at baseline and at the 6- and 12-month visits. Only right eye data were analysed. Repeated-measures analysis of covariance was performed to examine the differences in axial elongation and the RPRC between the BCA and BCS groups. RESULTS: The 1-year results from 31 BCA and 32 BCS subjects were analysed. No significant between-group differences were found at baseline (p ≥ 0.28). At the 12-month visit, the BCA lens produced a greater absolute RPRC along the horizontal meridian than the BCS lens (p < 0.001). Axial elongation was slower in the BCA group (0.19 ± 0.20 mm) than in the BCS group (0.29 ± 0.14 mm; p = 0.03). Axial elongation was correlated with the RPRC at 10° (r = 0.43, p = 0.02) and 20° (r = 0.39, p = 0.03) along the temporal retina in the BCA group; however, these correlations were not observed in the BCS group. CONCLUSION: The BCA ortho-k lens could improve the efficacy of slowing axial elongation in children. The improved myopia control observed in the BCA group may be the result of a larger myopic shift in relative peripheral refraction within 20° along the temporal retina.

Machine learning models for orthokeratology lens fitting and axial length prediction.

PURPOSE: In order to improve the efficiency of orthokeratology (OK) lens fitting and predict the axial length after 1 year of OK lens wear, machine learning models were proposed. METHODS: Clinical data from 1302 myopic subjects were collected retrospectively, and two machine learning models were implemented. Demographic and corneal topographic data were collected as input variables. The output variables were the parameters of the OK lens and the axial length after 1 year. Eighty percent of input variables was used as the training set and the remaining 20% was used as the validation set. The first alignment curve (AC1) of the OK lenses, deduced using machine learning models and formula calculation, were compared. Multiple regression models (support vector machine, Gaussian process, decision tree and random forest) were used to predict the axial length after 1 year. In addition, we classified data based on lens brand, and carried out more detailed parameter fitting and analysis for spherical and toric OK lenses. RESULTS: The OK lens fitting model showed higher (R2 = 0.93) and lower errors (mean absolute error [MAE] = 0.19, mean square error [MSE] = 0.09) when predicting AC1, compared with the formula calculation (R2 = 0.66, MAE = 0.44, MSE = 0.25). The machine learning model still had high R2 values ranging from 0.91 to 0.96 when considering the brand and design of the OK lenses. Further, the R2 value for the axial length prediction model was 0.94, which indicated that the machine learning model had high accuracy and good robustness. CONCLUSION: The OK lens fitting model and the axial length prediction model played an important role in guiding OK lens fitting, with high accuracy and robustness in prediction performance.

Effects of orthokeratology lenses on tear film and tarsal glands and control of unilateral myopia in children.

Introduction: To investigate the effects of an orthokeratology lens on the tear film and tarsal glands and myopia control in children with unilateral myopia using an intelligent analysis model. Methods: We retrospectively reviewed the medical records from November 2020 to November 2022 of 68 pediatric patients with unilateral myopia in Fujian Provincial Hospital who had been wearing an orthokeratology lens for more than 1 year. The 68 myopic eyes were included in the treatment group, while the 68 healthy, untreated contralateral eyes were included in the control group. Tear film break-up times (TBUTs) were compared between the two groups at various intervals, and an intelligent analysis model was used to compare the deformation coefficients of 10 meibomian glands in the central area and the different positions of the glands in the two groups after 12 months of treatment. Changes in axial length and equivalent spherical power were also compared between the groups before and after 12 months of treatment. Results: In the treatment group, TBUTs differed significantly between 1 and 12 months after treatment, although no significant differences from baseline were observed at 3 or 6 months. No significant differences in TBUTs were observed at any time point in the control group. After 12 months of treatment, significant between-group differences were observed for glands 2, 3, 4, 5, 6, 7, 8, and 10 (numbered from the temporal to nasal regions). The treatment group also exhibited significant differences in deformation coefficients at different detection positions in the central region, with glands 5 and 6 exhibiting the highest deformation coefficients. Increases in axial length and equivalent spherical power were significantly greater in the control group than in the treatment group after 12 months of treatment. Discussion: Wearing orthokeratology lenses at night can effectively control myopia progression in children with unilateral myopia. However, long-term use of these lenses may lead to meibomian gland deformation and impact tear film function, and the extent of deformation may vary at different positions in the central region.

Long-term effects of tear film component deposition on the surface and optical properties of two different orthokeratology lenses.

PURPOSE: To understand the effects of long-term deposition of tear film components on the surface and optical properties of orthokeratology (ortho-k) lenses, two different lenses, Brighten 22 and Optimum Extra, were tested here. METHODS: Ortho-k lenses were immersed in artificial tears and cleaned with a commercial care solution repeatedly for up to 90 days. Both the daily and accumulated lysozyme deposition amounts using an Enzyme-Linked ImmunoSorbent Assay were then analyzed. The base curve, central thickness, power, and transmission of visible light, ultraviolet A, and ultraviolet B were analyzed before and after repeated tear film component deposition procedures. The surface roughness using atomic force microscopy was observed and an energy dispersive spectrometer was used to analyze the composition of the deposits. RESULTS: The highest levels of lysozyme were adsorbed on both lens materials during the first four days of the procedure and became saturated by day 6. For both lens materials, contamination on the lenses was easily observed by day 30, and the degree of surface roughness was higher. The transmission levels of different light spectrums were reduced showing that the optical characteristics of both lenses were also affected. CONCLUSIONS: The results provide in vitro evidence that lysozyme could not be completely removed from orthokeratology lenses. Both surface and optical properties were affected by the deposition of tear film components. However, only one commercial multipurpose care solution was used to clean the lens in this study when the main ingredient was a surfactant, and the results might be different when other care regimens with other key ingredients are used. In addition, whether tear film component deposition might result in increased risks of infection or corneal abrasion will require further investigation.

Biomechanical study of cornea response under orthokeratology lens therapy: A finite element analysis.

Orthokeratology (OK) is becoming a mainstream modality for myopia correction and control, but its underlying mechanism is not yet fully understood. In this study, the biomechanical response of cornea under the OK lens was investigated to further understand the mechanism of OK therapy. Numerical models of the cornea and OK lens with different corneal refractive powers and myopia degrees were established to analyze features and differences of the spatial displacement and stress distribution in different areas of the anterior corneal surface by finite element method. Displacement distributions on the anterior cornea surface with refractive powers of 39.5, 43, 46 D, and myopia degrees of -1.0, -3.0, -6.0 D demonstrate similar deformation trends and nearly rotationally symmetrical attributes of different corneal parameters. Displacement of mid-peripheral cornea was significantly high compared with that of the central and peripheral cornea, peaking at ~2.4 mm off the corneal apex. The stress increased with the increase in myopia degrees and was significantly large for the myopia degrees of -6.0 D at S1; the stress at S2 and S6 was low and stable and did not differ much at S3; the stress at S4 and S5, however, was extremely high. In summary, simulation result of orthokeratology can effectively evaluate the performance of OK lens and it properly associates with the differential map of the corneal topography. The base curve of the OK lens may also play a role in mid-peripheral corneal steepening. The design around the OK lens' alignment curve needs to be optimized.

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

BACKGROUND: To investigate the effects of orthokeratology (ortho-k) lenses with aspheric and spherical base curve designs on corneal refractive power (CRP) and peripheral refraction. METHODS: Children aged 8 to 12 years with myopia between -0.75 D to -4.00 D, astigmatism ≤1.00 D, and corneal astigmatism ≤1.50 D were randomly assigned to the base curve aspheric (BCA) and base curve spherical (BCS) ortho-k lens groups. CRP was assessed for the central 8 mm cornea along horizontal and vertical meridians, and peripheral refraction was measured at 10°, 20°, and 30° along the nasal and temporal retina. Primary measurements included relative corneal refractive power change (RCRPC) and relative peripheral refraction change (RPRC). RESULTS: The 3-month results of the 33 and 29 subjects (right eye only) in the BCA and BCS groups, respectively, were obtained. Nonsignificant differences were found in the baseline data between the two groups (p > 0.05). At the 3-month follow-up visit, the mean RCRPC in the BCA group (2.08 ± 0.65 D) was significantly greater than that in the BCS group (1.32 ± 0.81 D) (F1,51 = 25.25, p < 0.001). The BCA group (-1.82 ± 0.65 D) exhibited a larger absolute RPRC than the BCS group (-0.98 ± 0.54 D) (F1,57 = 33.73, p < 0.001). CONCLUSIONS: It was found that the BCA ortho-k lens resulted in a more aspheric treatment zone and a more myopic relative peripheral refraction (RPR) along the horizontal meridian. The more myopic RPR was contributed by a more hyperopic central refraction and a more myopic peripheral refraction in the BCA group.

[Observational Comparison of the Safety and Effectiveness of Myopic Children Wearing Defocus Incorporated Soft Contact Lenses or Orthokeratology Lenses].

Objective: To observe and compare the effectiveness and safety of controlling myopia in children by wearing defocus incorporated soft contact (DISC) lenses or orthokeratology (OrthoK) lenses. Methods: A total of 75 children who came to our hospital between January 2018 and September 2020 were enrolled for this retrospective study. The DISC group consisted of 30 myopic children (60 eyes) wearing peripheral defocal soft incorporated contact lenses during daytime. There were 10 males and 20 females aged (9.9±1.00) years old in this group and their spherical equivalent refractions were (-2.78±0.70) D. The OrthoK group consisted of 45 myopic children (90 eyes) wearing OrthoK lenses. There were 30 female and 15 males aged (9.67±1.11) and their spherical equivalent refractions were (-2.67±0.71) D. All subjects had previously worn prescription glasses for 12 months or longer before they started wearing contact lenses. The subjects were followed up for 12 months once they started wearing contact lenses. The axial changes and corneal and conjunctival complications of the two groups of myopic children were compared and analyzed. Results: Myopic children in both groups experienced relatively rapid increase in ocular axial length while they were wearing prescription glasses, with the ocular axial length increase in the prescription-glass-wearing period being (0.34±0.09) mm in the OrthoK group and (0.37± 0.07) mm in the DISC group. In the 12 months of wearing contact lenses, the ocular axial length of children in the OrthoK group increased by (0.18±0.04) mm, while that of the DISC group increased by (0.19±0.05) mm. The increase in ocular axial length was reduced in both groups after the children were switched to the new myopia prevention methods, showing significant difference ( P<0. 05). The two groups using two different contact lenses had similar axial length increase, showing no significant difference ( P>0.05). During the 12-month period while the subjects wore the two types of contact lenses, the incidence of chronic follicular conjunctivitis was 11.20% in the OrthoK group and 20.00% in the DISC group, with that of the DISC group being slightly higher without showing significant difference ( P>0.05). The incidence of grade-1corneal staining was 66.70% in the OrthoK group and 56.70% in the DISC group, and the incidence of grade-2 corneal staining was 17.80% in the OrthoK group and 16.70% in the DISC group. In other words, the OrthoK group had slightly higher findings, but the difference was not significant ( P>0.05). The incidence of contact lens-associated papillary conjunctivitis was 2.20% in the OrthoK group and 10.00% in the DISC group, which was slightly higher than that in the orthokeratology lens group, but the difference was not significant( P>0.05). Conclusion: Both DISC lenses and OrthoK lenses can effectively control the increase in axial length in myopic children, and their have better effects than those of prescription glasses. The two tyes of contact lenses showed similar effects for controlling axial length increase. Both contact lenses have fewer corneal and conjunctival complications and better safety.

Long-term changes in the ocular surface during orthokeratology lens wear and their correlations with ocular discomfort symptoms.

PURPOSE: To evaluate the changes in ocular surface parameters during orthokeratology lens wear and determine their correlations with ocular discomfort symptoms. METHODS: Fifty individuals were enrolled in this prospective pilot study. Clinical evaluation of the ocular surface included the ocular surface disease index, slit-lamp examination, Keratograph 5M, optical quality analysis system, and corneal staining. After baseline examinations, clinical tests were performed at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months after orthokeratology lens wear. Correlations between ocular discomfort symptoms and signs of ocular discomfort were evaluated. RESULTS: Overall ocular surface disease index score and two subscale scores (ocular symptoms and vision-related function) significantly increased at the 3-month visit (P < 0.05), and decreased to levels close to baseline at the12-month visit (P > 0.05). The basic objective scatter index and the mean tear film objective scatter index increased, peaking at 3-month visit (P < 0.05) and gradually decreased thereafter. The modulation transfer function cut-off significantly decreased at the 3-month visit (P < 0.05). During the 12-month study period, the overall ocular surface disease index score and vision-related function score were significantly and positively correlated with the basic objective scatter index and mean tear film objective scatter index (P < 0.05). After 1 week of lens wear, Grade 1 corneal staining increased to 16.4 %, mostly involving the central and inferior cornea. CONCLUSIONS: Orthokeratology lens wear increased ocular discomfort symptoms and decreased the function of tear film, mainly within 3 months of lens wear. Tear-related visual function parameters were correlated with ocular discomfort. A new parameter, tear film objective scatter index, measured with the optical quality analysis system, was more sensitive in detecting the quality and stability of tear film than traditional indicators.

Effects of wearing orthokeratology lens on ocular surface and meibomian gland in children and adolescents of different ages / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the effect of orthokeratology lens on ocular surface and meibomian gland in children and adolescents of different ages.METHODS: A total of 120 cases(240 eyes)of myopic children and adolescents treated in the optometry clinic of our hospital from December 2020 to February 2021 were retrospectively selected, and they were divided into the orthokeratology group(60 cases, 120 eyes)and the frame glasses group(60 cases, 120 eyes)according to the myopia correction methods. The changes in ocular surface and meibomian gland after wearing glasses were analyzed, and those changes in patients of different ages were compared between the two groups.RESULTS: Corneal curvature decreased, non-invasive tear film break-up time(NIBUT)shortened and meibomian gland score increased at 3, 6, 9 and 12mo in the orthokeratology group after wearing lens, while lower tear meniscus height increased at 6, 9 and 12mo compared with that before wearing lens. In the frame glasses group, the lower tear meniscus height was higher at 6 and 9mo than that before wearing glasses(both P&#x003C;0.05). At the same time point, the corneal curvature of the orthokeratology group was significantly lower than that of the frame glasses group at all time points, the NIBUT at 3, 9 and 12mo after wearing the lens was shorter than that of the frame glasses group and the meibomian gland scores were higher at 6, 9 and 12mo than those at the same time point in the glasses group(all P&#x003C;0.05). After wearing lens for 12mo, the corneal curvature of the orthokeratology group at all ages was significantly lower than that of the frame glasses group, the NIBUT of the orthokeratology group at 8 to 12 years old and 13 to 15 years old was significantly lower than that of the frame glasses group, and the meibomian gland score was significantly higher than that of the frame glasses group(all P&#x003C;0.05).CONCLUSION: Orthokeratology lens may affect the ocular surface and meibomian glands function, and the effects on ocular surface are more pronounced in children and adolescents under 12 years old. Therefore, younger children and adolescents could be prioritized for myopia correction with framed glasses, and then wearing orthokeratology lens when they get older.