Orthokeratology Lenses Research Articles

Incidence of microbial keratitis associated with overnight orthokeratology: a multicenter collaborative study.

To investigate the incidence of microbial keratitis among Japanese patients wearing orthokeratology (ortho-k) lenses STUDY DESIGN: Retrospective multicenter study METHOD: This study was conducted at 4 hospitals in Japan and involved 1438 patients who had been prescribed ortho-k lenses and had worn them for at least 3 months. Data on patient demographics, lens characteristics, lens care systems, and presence of microbial keratitis were extracted from the medical records. Duration of ortho-k lens wear was calculated from the original fitting date to the patient's last visit, with the total years of lens wear used as person-years of lens wear. The incidence of microbial keratitis was calculated by dividing the number of infected cases by the total person-years of lens wear for all enrolled participants. Among the 1438 patients, 753 were male and 685 were female, with a mean age of 12.7 ± 5.4 years. The mean duration of ortho-k lens wear was 5.2 ± 4.5 years, and the mean lens power was -3.52 ± 1.41 D. The total person-years of lens wear for all enrolled patients was 7415. Four cases of microbial keratitis were identified, resulting in an overall incidence of microbial keratitis of 5.4 (95% CI: 1.0-9.8) per 10,000 patient-years among ortho-k lens wearers. This study represents the largest sample size to date for estimating the incidence of microbial keratitis associated with ortho-k lenses. The incidence was similar to or slightly lower than that of previous studies on ortho-k-related microbial keratitis and also comparable to that of daily wear soft contact lenses.

Corneal asymmetry contributes decentration in both sphericaland toric orthokeratology lenses.

To discuss the characteristics of anterior corneal elevation asymmetry in myopic eyes and clarify which kind of asymmetry most influenced lens position. 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. 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. 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.

Efficacy comparison of repeated low-level red-light therapy and orthokeratology lenses for myopia control.

This study aimed to compare and analyze the efficacy of repeated low-level red-light therapy and orthokeratology lenses for myopia control in children. Exactly 138 participants were enrolled in this retrospective study. Comprehensive eye examinations were performed prior to treatment. The repeated low-level red-light therapy and orthokeratology lenses groups comprised 67 and 71 patients, respectively. The age range was between 6 and 14 years, with myopia of ≤-0.50 D and astigmatism of ≤2.50 D after cycloplegia. Follow-up data were collected during the initial visit and the treatment period. Changes in axial length over a 2-year period and associated factors were analyzed. Over the 2-year period, the repeated low-level red-light therapy group exhibited significantly less axial length growth compared with the orthokeratology lenses group (0.17 ± 0.40 vs. 0.50 ± 0.27 mm, p<0.001). In the first year, the axial length growth in the repeated low-level red-light therapy group was significantly less than that in the orthokeratology lenses group (0.03 ± 0.22 vs. 0.28 ± 0.18 mm, p<0.001), with no significant difference observed in the second year (0.14 ± 0.29 vs. 0.21 ± 0.14 mm, p=0.06). The repeated low-level red-light therapy group showed a 55% reduction in axial length after 1 month and a 42% reduction after 1 year, compared with 4% and 3% reductions in the orthokeratology lenses group, respectively. Linear mixed-effects model analysis indicated that the annual axial length change rate in the repeated low-level red-light therapy group was 0.10 mm (95% confidence interval [CI], 0.07 to 0.14), compared with 0.25 mm in the orthokeratology lenses group (95% CI, 0.24 to 0.27), with an average difference of 0.15 mm (95% CI, -0.17 to -0.12, p<0.001). Repeated low-level red-light therapy demonstrated slightly superior efficacy in controlling myopia progression in children compared with orthokeratology lenses.

Multifocal Rigid Gas Permeable Contact Lenses with Multi-Tangential Positioning and Corrected Spherical Aberration for Myopia Control

Slowing the progression of myopia has become an extensive concern for parents of children with myopia. According to research findings in animals, eye growth is primarily influenced by the peripheral retina. Treatment options such as orthokeratology, daytime bifocal or multifocal soft contact lens usage are available because they can induce relative myopia in the periphery. In this work, a new multifocal rigid gas permeable (MFRGP) contact lens for myopia prevention and control in adolescents was designed specifically for preventing and controlling myopia in adolescents. This lens features a multi-tangent alignment curve, smaller spherical aberration, and transition defocus. FocalPoints and UPC 100 Vision were used for lens design and lathing, respectively. The lens structure and power profile were measured using IS830 and CONTEST 2, respectively. The elimination of lens aberrations was achieved through design optimization using ZEMAX with ray tracing. Lens fitting was evaluated using slit-lamp microscopy and corneal topography.

Orthokeratology lens care: Surface treatment by an atmospheric pulsed microwave air plasma jet

Orthokeratology lens care: Surface treatment by an atmospheric pulsed microwave air plasma jet

Orthokeratology for high myopia

Purpose. With an increasing proportion of children with myopia especially in Asia, efforts have been made to reduce chances of preventable sight loss related to high myopia in the future. Orthokeratology lens has been used as one of the modalities not just to correct myopia, but also to slow down myopic progression and axial elongation. This case report reviews a patient with clinically significantly high myopia, whose refractive errors was partially corrected with orthokeratology lens and spectacle lenses. Material and Methods. A now 14-year-old patient with a history of fast progressing myopia, was prescribed and commended orthokeratology to manage myopia, while regularly monitoring her refractive errors, axial length, binocular vision status, corneal topography, and anterior eye health was monitored regularly at the author’s practice. Results. Over a two year follow up period, a partial correction of high myopia with orthokeratology lenses and residual refractive errors with additional spectacle lenses was effective in managing this patient’s myopia, as well as slowing of axial elongation. An updated pair of orthokeratology lens with a steeper back optic zone radii were prescribed to reduce superficial corneal staining and to maintain corneal health. Conclusion. Patient commitment and adherence to close monitoring of eyes in terms refractive errors, axial length, and anterior eye health, are vital in achieving a successful orthokeratology lens wear for high myopia. A dual fitting strategy consisting of orthokeratology lens and spectacle wear can be a safe management strategy that is acceptable for patients with high myopia. It would be helpful for practitioners to be able to rely on robust evidence-based guidance when determining whether lens wear can be ceased, i.e. when further axial elongation and myopic progression are no longer likely.

Clinical Investigation of Short-Term Axial Elongation Control After Orthokeratology Lens Correction: Exploring Its Predictive Role in Long-Term Therapeutic Efficacy

Objective: This study was developed with the goal of exploring the efficacy of orthokeratology (OK) as an approach to controlling axial length (AL) growth and identifying factors predictive of the long-term efficacy of this approach. Methods: This was a retrospective study that enrolled 157 myopic children 7 to 15 years of age undergoing OK correction for over 3 years. The short- and long-term effectiveness of this approach at 1 and 3 years post-OK correction, respectively, was assessed. All participants were classified into two groups based on whether they exhibited good or poor long-term efficacy outcomes. Measurements of changes in AL were made at baseline and at 1 and 3 years post-OK. Univariate analyses and binary logistic regression approaches were used to evaluate baseline age, baseline spherical equivalent refraction, baseline keratometry (K) values of flat and steep meridians, and short-term effectiveness with the goal of identifying predictors of long-term efficacy. Results: Univariate analyses led to the identification of significant differences in baseline age, baseline spherical equivalent refraction, baseline AL, and short-term efficacy between these two groups (P&lt;0.05), whereas gender, baseline flat K, and baseline steep K did not differ significantly (P&gt;0.05). In binary logistic regression analyses, baseline AL (P=0.017) and short-term efficacy (P&lt;0.001) were both found to significantly influence long-term efficacy. Receiver operating characteristic curves demonstrated that short-term efficacy offered an area under the curve value &gt;0.8, consistent with its highly accurate performance as a predictor of long-term efficacy. Conclusion: These results suggest that short-term efficacy outcomes can feasibly be used to predict the long-term effectiveness of OK correction in children. In patients exhibiting poor short-term efficacy, timely replacement or the incorporation of additional treatment modalities may aid efforts to better control the progression of myopia.

Myopia control with orthokeratology lenses. A 3-year follow-up study including a cross-over design: Clinical study Of Near-sightedness; TReatment with Orthokeratology Lenses 2 (CONTROL2 study).

The purpose of this study is to investigate 3-year efficacy of orthokeratology lenses (OKL) in controlling axial length progression in myopic Scandinavian children. Through a cross-over design of the control group to compare the treatment efficacy in younger versus older children, with the latter having higher cycloplegic spherical refractive error (cSEQ) at treatment initiation. Further, the study aimed to evaluate the safety of the treatment. This was a continuation of the randomized controlled study Clinical study Of Near-sightedness; TReatment with Orthokeratology Lenses (CONTROL study) in which the follow-up period of the original intervention group, that received OKL, was extended from 18 months to 36 months. Meanwhile, the original control group was crossed-over to OKL after the 18-month follow-up visit and treated for 18 months. Biometry was measured using Lenstar LS900, and contact lens complications were graded according to Efron Grading Scale for Contact Lens Complications (Efron score). Mixed models were used for statistical analysis. Nineteen subjects in the OKL group and 28 in the control group completed the CONTROL study. Hereof, 17 and 24 subjects from the OKL group and control group, respectively, agreed to participate in the CONTROL2 study. In the OKL continue group, the treatment efficacy did not decline during the 3-year study period (p-values for follow-up visits were all ≥0.82). There was no statistically significant difference between treatment efficacy when OKL treatment was initiated in younger versus older children (p-value ≥0.14 for all follow-up visits). Low-grade corneal staining was seen in several subjects at some point during the study, but here were no treatment-requiring or sight-threatening adverse events during the study period. The efficacy of myopia control by OKL was stable during 3 years of treatment. Similar treatment efficacies were found regardless of the age at treatment initiation. No severe adverse events occurred during the study period.

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

To elucidate whether differences exist in the impact on retarding the elongation of axial length (AL) among children with myopia when utilizing orthokeratology (ortho-k) lenses employing the corneal refractive therapy (CRT) design versus those employing the vision shaping treatment (VST) design. This retrospective clinical trial aimed to collect and analyze AL data from individuals who wore ortho-k lenses for three years. A total of 654 subjects were enrolled and prescribed one of the three specific brands of ortho-k lenses: CRT, Euclid, and Mouldway. The study's primary focus was to compare the rates of AL elongation and myopic progression across these three brands of ortho-k lenses. In the 3-year follow-up, the AL elongation exhibited variations of 0.73±0.36 mm in the CRT lens group, 0.59±0.37 mm in the Euclid lens group, and 0.63±0.38 mm in the Mouldway lens group. A noteworthy disparity emerged between the CRT and Mouldway groups (P<0.01), as well as between the CRT and Euclid groups (P<0.001). Additionally, it was observed that 32.1% of participants who wore CRT lenses experienced a decelerated progression of myopia, in contrast to 47.2% in the Euclid group and 44.4% in the Mouldway group. Statistical analyses revealed a statistically significant distinction between the CRT and Euclid groups (P<0.01), and similarly, the CRT group demonstrated a statistically significant difference when compared to the Mouldway group (P<0.05). Ortho-k lenses represent a pragmatic strategy for mitigating the advancement of myopia. In contradistinction to ortho-k lenses utilizing the CRT design, those employing the VST design exhibited a more favorable impact regarding retarding AL elongation.

ATROPINE FOR MYOPIA CONTROL: EFFICACY, CHALLENGES AND FUTURE DIRECTIONS

Myopia, or near-sightedness, is rapidly emerging as a major global health issue, with projections indicating that by 2050, it will affect nearly 50% of the world’s population. This condition arises from excessive elongation of the eyeball, leading to blurred vision at a distance and increasing the risk of severe ocular complications, such as retinal detachment and glaucoma. Effective management strategies are critical to mitigating the public health impact of this growing epidemic. Atropine, a muscarinic antagonist, has gained attention for its potential in myopia control. By inhibiting muscarinic acetylcholine receptors (mAChRs) in the eye, atropine slows down axial elongation, the anatomical hallmark of myopia. Low-dose atropine (0.01%) has demonstrated efficacy in clinical trials, such as the ATOM2 study, which showed a 50% reduction in myopia progression with minimal side effects, including photophobia and blurred vision. Meanwhile, the LAMP study indicates that slightly higher concentrations (0.05%) may further balance efficacy and tolerability, especially in children at high risk of severe myopia. Despite these promising results, critical knowledge gaps persist, particularly concerning atropine’s long-term safety, optimal dosing, and the rebound effect, where myopia progression may accelerate after stopping treatment. Ethnic and genetic variability also calls for a more diverse research focus. Future studies should explore combining atropine with other interventions, such as orthokeratology or multifocal lenses, to optimize outcomes. As leading pharmacological option for myopia management, atropine holds potential for integration into multifaceted treatment strategies to address this pressing public health concern. KEYWORDS: Atropine, Myopia, Pediatric Populations, Muscarinic Acetylcholine Receptors, LAMP.

Corneal and intraocular pressure changes associated to the circadian rhythms: a narrative review.

To synthesize the current body of research regarding the diurnal variations in intraocular pressure (IOP) and corneal biomechanical and morphological parameters, highlighting their significance in various eye conditions. A comprehensive review of studies on the diurnal variations of IOP and corneal parameters was conducted. Tonometry findings from various studies were assessed, including the Goldmann applanation tonometry (GAT) and non-contact tonometers. Data on the variations in central corneal thickness (CCT), corneal curvature, and corneal biomechanics measured by the Ocular Response Analyzer system across different population groups was extracted and analyzed. In both healthy subjects and those with Fuchs dystrophy, IOP and CCT demonstrate marked diurnal declines. GAT remains the gold standard for tonometry, with the highest reliability. However, its measurements are influenced by CCT. Keratoconus patients and those with pseudoexfoliation showed significant diurnal variations in IOP. The biomechanical parameters, especially corneal hysteresis (CH) and the corneal resistance factor (CRF), largely remain stable throughout the day for most of eye conditions, with some exceptions. Notably, the corneal morphology diurnal variation, particularly curvature, yielded mixed conclusions across studies. Circadian rhythms significantly influence various corneal parameters, most notably IOP and CCT. Further studies should emphasize standardized approaches larger sample sizes, and delve deeper into less-explored areas, such as the effects of orthokeratology lenses on diurnal biomechanical shifts.

An integrative predictive model for orthokeratology lens decentration based on diverse metrics.

To develop a predictive model for orthokeratology (Ortho-K) lens decentration 1 month after wear. This study included myopic children who were fitted with Ortho-K lenses at Fujian Provincial Hospital between December 2022 and May 2024. Corneal topography parameters and other relevant metrics were collected pre- and post-treatment. Feature selection was conducted using univariate logistic regression and Lasso regression analysis. A machine learning approach was used to develop multiple predictive models, including Decision Tree, Logistic Regression, Multilayer Perceptron, Random Forest, and Support Vector Machine. Model performance was evaluated using accuracy, sensitivity, specificity, ROC curves, DCA curves, and calibration curves. SHAP values were employed to interpret the models. The Logistic Regression model demonstrated the best predictive performance, with an AUC of 0.82 (95% CI: 0.69-0.95), accuracy of 77.59%, sensitivity of 85%, and specificity of 61.11%. The most significant predictors identified were age, 8 mm sag height difference, 5 mm Kx1, and 7 mm Kx2. SHAP analysis confirmed the importance of these features, particularly the 8 mm sag height difference. The Logistic Regression model successfully predicted the risk of Ortho-K lens decentration using key corneal morphological metrics and age. This model provides valuable support for clinicians in optimizing Ortho-K lens fitting strategies, potentially reducing the risk of adverse outcomes and improving the quality of vision for patients. Further validation in clinical settings is recommended.

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

This study analyzed the corneal surface shape following overnight orthokeratology with different optical zone diameters. A total of 82 eyes belonging to 41 myopic children who completed 1 month of the orthokeratology (ortho-k) lens wear at the Eye Hospital of Wenzhou Medical University from January 2022 to January 2023 were retrospectively analyzed. According to the size of the base curve (BC) of ortho-k lens, patients were divided into BC 5.0 and BC 6.0 groups. The changes in decentration distance and corneal refraction of the two groups after the ortho-k lens wear were analyzed. Independent sample t-tests were used to compare these two outcome measures between the two groups. The decentration distance of BC 5.0 group (0.37 ± 0.19 mm) was significantly lower than that of BC 6.0 group (0.49 ± 0.25 mm, t = -2.330, p = 0.022). In the BC 5.0 group, the direction of decentration was superonasal in 3 cases, inferonasal in 2 cases, inferotemporal in 21 cases, and superotemporal in 6 cases. In the BC 6.0 group, the direction of decentration was superonasal in 2 cases, inferonasal in 2 cases, inferotemporal in 27 cases, and superotemporal in 19 cases. The optical zone area (8.19 ± 2.96 mm2) and reverse curve zone area (30.05 ± 6.74 mm2) in the BC 5.0 group were significantly lower than in the BC 6.0 group (10.42 ± 2.03 mm2, t = -4.043, p < 0.001; 38.21 ± 4.77 mm2, t = -6.422, p < 0.001). The change in the rate of refraction in the horizontal direction in BC 5.0 group were significant higher than in BC 6.0 group. Base curve 5.0 mm ortho-k lens is better positioned than BC 6.0 mm lens. A small BC ortho-k forms a smaller optical zone and reverse curve area, which might get a greater aiameter of alignment curve to facilitate positioning better than the traditional BC lens. In addition, a small BC lens increases positive refraction in the peripheral area, resulting in a greater negative pressure than the traditional BC lens.

Effects of orthokeratology and spectacle lenses with highly aspherical lenslets on unilateral myopic anisometropia control.

To evaluate the 1-year effects of orthokeratology (OK) lenses and spectacle lenses with highly aspherical lenslets (HALs) on axial length (AL) elongation in children with unilateral myopic anisometropia. This ambispective cohort study recruited 81 children aged 8-14 years with unilateral myopic anisometropia. Of these, 42 participants (mean age 11.07 ± 1.54 years; 23 males) were treated with monocular OK lenses (OK group), and 39 (mean age 10.64 ± 1.72 years; 22 males) with binocular HALs (HAL group). Changes in AL and spherical equivalent refraction (SER) from baseline at 3, 6 and 12 months were compared between eyes and groups. Kaplan-Meier estimation and Cox proportional hazard regression were performed to analyse the risk of myopia onset in the initially non-myopic eyes. Mean axial elongation in the myopic and non-myopic eyes at the 12-month follow-up visit were 0.17 ± 0.20 and 0.41 ± 0.26 mm in the OK group (p < 0.001) and 0.10 ± 0.15 and 0.12 ± 0.12 mm in the HAL group (p = 0.32), respectively. Compared with the OK group, the non-myopic eyes in the HAL group had less axial elongation, lower cumulative myopia incidence and percentage of participants with rapid myopic shift at the 6- and 12 month follow-up (all p < 0.05). Cox regression analysis showed that a higher initial SER decreased the risk of myopia onset significantly in the initially non-myopic eyes (B = -2.06; 95% CI, 0.03-0.49; p = 0.003). Monocular OK lenses suppressed axial elongation in the myopic eye and minimised anisometropia; however, the non-treated contralateral eye may experience faster myopia onset and myopic shift. Binocular HALs can effectively reduce axial elongation in both eyes of children with unilateral myopic anisometropia.

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

To investigate the clinical features and visual outcome of infectious keratitis associated with orthokeratology (Ortho-K) lens in Korean pediatric patients. We retrospectively reviewed medical records of patients diagnosed with Ortho-K lens-related 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. The study included 26 eyes from 26 patients (19 female and 7 male patients; 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 (11 of 26 cases, 42.3%). Central or paracentral corneal lesions were observed in 25 cases (96.2%), 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 best-corrected visual acuity [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 (p = 0.043), duration from symptom onset to presentation (p = 0.040), and corneal epithelial defect size (p = 0.002) were significantly associated with final logarithm of the minimum angle of resolution BCVA. 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; odds ratio, 38.995; p = 0.030). 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.

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

To compare the control effectiveness and periretinal defocus between orthokeratology (OK) and highly aspherical lenslets (HAL) in adolescents with myopia. In this prospective study, 211 children (211 right eyes) were enrolled in Beijing Ming Vision and Ophthalmology between October 2022 and February 2023. Based on the myopia correction method, participants were divided into three groups: OK, HAL, and single-vision spectacles (SVS). They were further divided into two subgroups according to the spherical equivalent (SE), namely, subgroup A with -1.0≤SE≤-2.0 D and subgroup B with -2.0<SE≤-3.0 D. All children were followed up for 12 months, and the changes in axial length (AL) and periretinal defocus before and after treatment were recorded, and the factors affecting the corneal shaping force for 1-day post-OK were analyzed. Axial length growth in those with OK lenses and HAL was lower than what was observed for those with SVS after 6, 9, and 12 months. Comparison of the difference in AL change between OK and HAL was not statistically significant with -1.0≤SE≤-2.0 D. The myopic defocus of RDV270° to 300° in group HAL was higher than that in group OK, the difference was statistically significant ( P <0.05), and in other regions, the myopic defocus was higher in the group OK. Em, SRI (corneal regularity index), variation in cell area, and corneal thickness were significantly associated with shaping force. Orthokeratology is one of the most effective optical treatments for controlling myopia, and the factors that affect the corneal shaping force under different corneal parameters are different. For mild myopia, HAL can achieve the same effectiveness as OK.

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

BackgroundTo 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.MethodsThis 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).ResultsA 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.ConclusionsCompared 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

Layer-by-layer self-assembled smart antibacterial coatings for surface management of orthokeratology lens

ABSTRACT Orthokeratology (OK) lenses are designed to reshape the cornea overnight, allowing users to see clearly during the day without glasses. However, prolonged wear increases the risk of microbial contamination and eye infections. Even with cleaning techniques, the surface of OK lenses can become contaminated due to residual bacterial debris. Therefore, developing self-cleaning antibacterial technology for OK lens surfaces is an urgent clinical challenge. Herein, we integrated the temperature responsiveness of PNIPAM molecular chains with the surface contact-killing mechanism of AMP into the surface of OK lenses for the first time, constructing an intelligent OK lens with synergistic antibacterial and self-cleaning properties. The modified OK lenses can achieve over 95% bacterial efficiency against Staphylococcus aureus and Pseudomonas aeruginosa. More importantly, in both worn and removed states, the modified OK lenses can achieve a surface bacterial debris self-cleaning efficiency of 50–75%. These research findings provide important references and insights for the future development of more efficient self-cleaning lens materials.

A protocol for a single center, randomized, controlled trial assessing the effects of spectacles or orthokeratology on dry eye parameters in children and adolescents

BackgroundThe prevalence of myopia among adolescents is increasing precipitously in China, and the popularity of orthokeratology (OK) lenses as an effective treatment for controlling myopia progression is rising. This protocol assessed and compared the clinical dry eye parameters in children and adolescents with myopia treated with spectacles or OK lenses. Methods and analysisThis single-masked randomized control trial will include 300 participants (aged 8–17 years) with myopia treated with OK lens (study group) or spectacles (control group). We will record the ocular surface disease index, visual analog scale score, noninvasive tear breakup time, tear meniscus height, meibomian gland score, ocular redness score, visual acuity, tear Matrix Metalloproteinase-9 concentration, tear Lymphotoxin alpha levels at baseline, and after 1-, 3-, 6-, and 12-month. DiscussionThis study will be a standardized, scientific, clinical trial designed to evaluate the dry eye parameters in children and adolescents with myopia treated with OK lenses for myopia control. Ethics and disseminationThis study has been approved by the Ethics Committee of He Eye Specialist Hospital [ethics approval number: IRB(2023)K024.01]. Before participating in the trial, written informed consent will be obtained from all patient's parents or guardians. The findings of this study will be showcased at both local and international conferences and will also be submitted for publication in reputable peer-reviewed journals. Trial registration numberClinicaltrials.gov: NCT06023108 {2a, 2b}

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

This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects. A meta-analysis was registered in PROSPERO (CRD42023408184). A comprehensive systematic database search was conducted, encompassing PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Ovid, CNKI and CBM, to identify relevant studies up to 25 March 2023. The primary inclusion criteria for this meta-analysis were studies that investigated the myopia control effect of OK lenses with a small optical treatment area (≤5 mm). To assess the quality of the retrieved articles, two researchers evaluated them using the Cochrane bias risk assessment criteria. The primary outcome measures were the changes in axial length (AL) and refractive error, using the weighted mean differences (WMD) and 95% confidence intervals (CI) to assess differences between small and traditional back optical treatment zone groups in terms of these outcomes. The analysis encompassed five eligible studies, with a 1 year duration. The average difference in AL between the groups was 0.12 mm (WMD = -0.12, 95% CI [-0.16, -0.09], p < 0.00001). Likewise, the average difference in refractive error between the two groups was 0.44 D (WMD = 0.44, 95% CI [0.30, 0.57], p < 0.00001). None of the studies reported severe adverse events. Current evidence suggests that OK lenses with smaller back optical treatment zone are more effective in preventing myopia progression than traditional lenses. However, a longer-term evaluation is warranted.