Orthokeratology Lenses Research Articles

Different efficacy in myopia control: Comparison between orthokeratology and defocus-incorporated multiple segment lenses

PurposeTo compare the efficiency of orthokeratology (OK) and defocus-incorporated multiple segment (DIMS) lenses in myopia control in children. MethodsThis prospective study involved 540 subjects (7–14 years) categorized into three groups: DIMS lenses (180 cases), OK lenses (180 cases), or single-vision spectacles (SVS) (180 cases). After a one-year follow-up, changes in axial length (AL) and differences among the groups were analyzed. The subjects were further divided into a low myopia degree subgroup (LM, −1.50 D ≤ SE ≤ −0.50 D), a moderate myopia degree subgroup (MM, −3.00 D ≤ SE ＜ −1.50 D), and a high myopia degree subgroup (HM, −5.00 D ≤ SE ＜ −3.00 D). A one-way ANOVA and multiple linear regression analysis were used to compare AL elongation and the factors influencing the different groups. ResultsA total of 496 (92 %) subjects completed the study. The mean AL change in the OK lenses, DIMS lenses, and SVS were 0.20±0.18 mm, 0.30±0.22 mm, and 0.38±0.19 mm, respectively (P < 0.001). In the LM subgroup, the OK and DIMS groups showed similar AL changes, but both exhibited slower changes than the SVS group (P = 0.001). In the MM and HM subgroups, the OK lens performed the shortest AL elongation compared with the DIMS lenses and SVS (P < 0.001). Multiple regression analysis showed that the AL change was associated with age (β = −0.038 and P = 0.005), initial AL (β = −0.010 and P = 0.011), initial SE (β = 0.028 and P = 0.007), and interventions using OK lenses (β = −0.172 and P = 0.020) and DIMS lenses (β = −0.089 and P = 0.020). ConclusionOver a one-year treatment period, OK and DIMS lenses can significantly retard AL elongation compared with SVS. In addition, the OK lenses were more effective than the DIMS lenses in controlling AL in patients with higher degrees of myopia.

Evaluation of the corneal topography based on deep learning.

The current study designed a unique type of corneal topography evaluation method based on deep learning and traditional image processing algorithms. The type of corneal topography of patients was evaluated through the segmentation of important medical zones and the calculation of relevant medical indicators of orthokeratology (OK) lenses. The clinical data of 1,302 myopic subjects was collected retrospectively. A series of neural network-based U-Net was used to segment the pupil and the treatment zone in the corneal topography, and the decentration, effective defocusing contact range, and other indicators were calculated according to the image processing algorithm. The type of corneal topography was evaluated according to the evaluation criteria given by the optometrist. Finally, the method described in this article was used to evaluate the type of corneal topography and compare it with the type classified by the optometrist. When the important medical zones in the corneal topography were segmented, the precision and recall of the treatment zone reached 0.9587 and 0.9459, respectively, and the precision and recall of the pupil reached 0.9771 and 0.9712. Finally, the method described in this article was used to evaluate the type of corneal topography. When the reviewed findings based on deep learning and image processing algorithms were compared to the type of corneal topography marked by the professional optometrist, they demonstrated high accuracy with more than 98%. The current study provided an effective and accurate deep learning algorithm to evaluate the type of corneal topography. The deep learning algorithm played an auxiliary role in the OK lens fitting, which could help optometrists select the parameters of OK lenses effectively.

Efficacy of the DRL orthokeratology lens in slowing axial elongation in French children.

This study aims to assess and compare the impact of Orthokeratology Double Reservoir Lens (DRL) versus Single Vision Lenses (SVL) on axial elongation and anterior chamber biometric parameters in myopic children over a 6- and 12-month treatment period in France. A retrospective study involving 48 patients aged 7 to 17 years, who underwent either orthokeratology treatment or single-vision spectacle correction, was conducted. Changes in refractive error, axial length, and anterior chamber depth were examined. Twenty-five patients comprised the Orthokeratology (OK) group, while twenty-three were in the control group (single-vision spectacle group). Significant increases in mean axial length were observed over time in both the control (0.12 ± 0.13 mm and 0.20 ± 0.17 mm after 6 and 12 months, respectively; F (2,28.9) = 27.68, p < 0.001) and OK groups (0.02 ± 0.07 mm and 0.06 ± 0.13 mm after 6 and 12 months, respectively; F (2,29.1) = 5.30, p = 0.023). No statistically significant differences in axial length were found between male and female children (p > 0.620). Age-specific analysis revealed no significant axial elongation after 12 months in the 14-17 years group in the OK group. Anterior biometric data analysis at 6 and 12 months showed statistical significance only for the DRL group. Orthokeratology resulted in an 86 and 70% reduction in axial elongation after 6 and 12 months of lens wear, respectively, compared to the single-vision spectacles group. Myopia progression was more pronounced in younger children, underscoring the importance of initiating myopia control strategies at early ages.

Targeting reactive oxygen species to ameliorate T cell-mediated inflammation in dry eye syndrome: a novel therapeutic approach.

Dry eye syndrome (DES) is a prevalent condition linked to oxidative stress from Orthokeratology (OK) lens use, causing significant discomfort and impacting quality of life. Herein, this study investigates the role of Reactive Oxygen Species (ROS) in modulating T cell responses, particularly Th17 cells and IL-17A production, which are central to DES pathogenesis. We propose a novel therapeutic strategy using ceria nanoparticles (CeNPs) for ocular ROS clearance, hypothesized to attenuate Th17 activation and IL-1β and IL-17A production, thereby reducing DES symptoms. We developed a hybrid coating for OK lenses using Schiff base reactions to link tannic acid with CeNPs, aiming to neutralize ROS and mitigate inflammation. This approach could offer a transformative treatment for DES, especially among OK lens users. In comparison to existing therapies, our approach demonstrated a 70% reduction in corneal inflammation markers and a 2.5-fold increase in tear secretion, offering a transformative treatment for DES, especially among OK lens users.

Comparison of myopic control between orthokeratology contact lenses and defocus incorporated multiple segments spectacle lenses.

Purpose: The purpose of this study was to compare the differences in myopic control effects between orthokeratology (OK) contact lenses and defocus incorporated multiple segments (DIMS) spectacle lenses. Methods: A retrospective cohort study was conducted that included patients who had received OK lens, DIMS spectacle lens or single-vision spectacle treatments. A total of 54 eyes from 27 individuals, 38 eyes from 19 individuals and 42 eyes from 21 individuals were enrolled into the OK lens, DIMS and control groups, respectively. The primary outcomes were the changes in the spherical equivalent refraction (SER) and axial length (AXL) among the groups. A repeated-measure ANCOVA was adopted to calculate the SER progression and AXL elongation of the OK lens group compared with the DIMS group. Results: The difference in the SER progression was clinically non-significant in the OK lens group compared with the DIMS and control groups (P = 0.001). The total AXL elongation results were similar between the OK lens and DIMS groups, but these were lower than in the control group (P = 0.005). The repeated-measure ANCOVA revealed that the SER progression difference during the study interval was clinically non-significant in the OK lens group when compared with the DIMS group (P = 0.028). The AXL elongation results between the OK lens and DIMS populations did not illustrate a significant difference (P = 0.607). In a subgroup analysis of moderate astigmatism, better AXL control was observed in the DIMS subgroup compared with the OK lens subgroup (P = 0.016). Conclusions: The OK lens demonstrated a clinically non-significant effect on the SER and AXL controls compared with the DIMS spectacle lens.

Влияние ортокератологических контактных линз на анатомо-функциональное состояние роговицы

Aim: To analyze the potential impact of orthokeratological lenses when correcting myopia on the anatomical and functional state of the cornea. 160 eyes (80 patients) were examined – 60 eyes (30 patients) with mild myopia, 100 eyes (50 patients) with moderate myopia, average age 12.0 ± 0.38 years. Control group – 40 eyes (20 patients), with emmetropia, average age – 13.0 ± 0.45 years. All patients used reverse geometry orthokeratological lenses «Moonlens» from «Sky Optix» in night mode. Research methods. Special research methods were carried out: keratotopography, OCT of the anterior segment of the eye, autorefractometry, ophthalmometry, biometry, skiascopy against the background of cycloplegia, ultrasound of the eye, biomicroscopy, ophthalmoscopy. Results. After the use of orthokeratological lenses, flattening of the cornea from the center to the periphery was revealed with the formation of a negative value of the asphericity index «Q» – exactly (-) 0.57±0.054 (p &lt;0.01); an increase in refraction in the middle and peripheral zones of the cornea with an increase in the asymmetry index «l-S» is 3.0±0.12D (p &lt;0.01). According to the SimK1 and SimK2 meridians, the degree of weakening of refraction in the center of the cornea was revealed (-) 2.32±0.19D and the degree of enhancement of refraction of the cornea in the middle and peripheral zones – (+) 61±0.53D and (+) 0.97 0, 11D. Conclusion. Thus, the identified changes in the anatomical and functional state of the cornea during the treatment of myopia with orthokeratological lenses in the night mode indicate a transformation of the induced myopic defocus.

Значение анатомо-структурных параметров глаза в эффективности лечения близорукости ортокератологическими линзами

Aim of the study. To study the importance of anatomical and structural parameters of the eye in the effectiveness of treatment with orthokeratological lenses in myopia. 200 eyes (100 patients) were examined, including 160 eyes (80 patients) with myopia – 60 eyes (30 patients) with a mild degree and 100 eyes (50 patients) with an average degree; mean age 12.0± 0.38 years, control group – 40 eyes (20 people) – healthy individuals with emmetropia. Research methods. Along with the generally accepted methods, autorefractometry (Grand Seiko VR-2100), ophthalmometry (Topcon KR-7309), biometry (Zeiss IOLMaster 500), keratotopography (root otopographic system SW-600), accommodation study – AKA-01 device, and Shapovalov S.L. method, skiascopy against the background of cycloplegia, ultrasound of the eye, ultrasound of the retinal vessels, OST-angiography, study of the hydrodynamics of the eye (Glau Test 60). Follow-up in 1-3-6-12-24 Months. Results. With the formation of induced myopia against the background of the use of orthokeratological lenses in mild and moderate myopia, an increase in the difference in corneal curvature between the central and peripheral zones was revealed – the coefficient «Q» is equal to (-) 0,56±0,05 mm and (-) 0,57 ±0,054 mm (Р &lt;0,001), in CG (-) 0,26±0,03 mm; increase in the index (asymmetry) «I-S» – before 2,78±0,18D and 3,22 0,12D (Р &lt;0,001), in CG –&gt;1,2±0,18D (Р &lt;0,01); increase in the frequency of refractive power amplification along the vertical and horizontal meridians (SimK1, Sim K2) by 37% and 44%; Normalization of hydrodynamic parameters: «Po» is normal in в 30%; increase «C» – up to 0,22 мм3/min (Р&lt;0,05); increase in AAA to 7,6 D±0,23 and 8,5D±0,01 (Р &lt;0,05) and 1,5 times – ZOA; increase in LSC in CAC to 15.0±0.64 cm/sec and in CVD – up to 5.5±0,59 cm/sec (Р &lt;0,05) with choroidal thickening to 301±1,9 мкм (Р &lt;0,05). Effectiveness of treatment with orthokeratological lenses: increase in NCOZ to 0.9-1.0 in 100%; reduction of the degree of myopia to (-) 0.55D±0.21 (P &lt;0.01); lack of reliable stretching of the AXL. Conclusion: One of the additional factors contributing to the effectiveness of the use of orthokeratological lenses in mild and moderate myopia are: activation of accommodation, normalization of hydrodynamics and hemodynamics of the eye.

Prediction of Myopia Eye Axial Elongation With Orthokeratology Treatment via Dense I2I Based Corneal Topography Change Analysis.

While orthokeratology (OK) has shown effective to slow the progression of myopia, it remains unknown how spatially distributed structural stress/tension applying to different regions affects the change of corneal geometry, and consecutive the outcome of myopia control, at fine-grained detail. Acknowledging that the underlying working mechanism of OK lens is essentially mechanics induced refractive parameter reshaping, in this study, we develop a novel mechanics rule guided deep image-to-image learning framework, which densely predicts patient's corneal topography change according to treatment parameters (lens geometry, wearing time, physiological parameters, etc.), and consecutively predicts the influence on eye axial length change after OK treatment. Encapsulated in a U-shaped multi-resolution map-to-map architecture, the proposed model features two major components. First, geometric and wearing parameters of OK lens are spatially encoded with convolutions to form a multi-channel input volume/tensor for latent encodings of external stress/tension applied to different regions of cornea. Second, these external latent force maps are progressively down-sampled and injected into this multi-scale architecture for predicting the change of corneal topography map. At each feature learning layer, we formally derive a mathematic framework that simulates the physical process of corneal deformation induced by lens-to-cornea interaction and corneal internal tension, which is reformulated into parameter learnable cross-attention/self-attention modules in the context of transformer architecture. A total of 1854 eyes of myopia patients are included in the study and the results show that the proposed model precisely predicts corneal topography change with a high PSNR as 28.45dB, as well as a significant accuracy gain for axial elongation prediction (i.e., 0.0276 in MSE). It is also demonstrated that our method provides interpretable associations between various OK treatment parameters and the final control effect. Our project code package is available at https://github.com/Rongdingyi/PhyIntNet.

Efficacy of repeated low-level red-light therapy combined with optical lenses for myopia control in children and adolescents.

To evaluate the efficacy of repeated low-level red-light (RLRL) therapy combined with optical lenses in children and adolescents with myopia. This retrospective study included 108 children and adolescents. Based on the difference in the combination intervention scheme participants were divided into four groups based on the intervention they received: the RLRL+orthokeratology (OK) lens intervention group (RLRL+OK group), the RLRL+defocus distributed multi-point (DDM) lens intervention group (RLRL+DDM group), the RLRL+single-vision spectacles (SVS) intervention group (RLRL+SVS group), and a control group. Visual acuity, spherical equivalent refraction (SER), and axial length (AL) were measured before and after the intervention. Binary logistic regression was used to identify factors influencing vision recovery. The SER and AL at baseline were statistically different (P<0.01). After the intervention, the AL increase in the RLRL+OK, RLRL+DDM, and RLRL+SVS groups was significantly better than the control group across time points (P<0.001). Changes in SER were also statistically significant in the RLRL+DDM and RLRL+SVS groups compared to the control group across time points (P<0.001). The intervention method was identified as a significant factor influencing vision recovery (P<0.001). RLRL therapy combined with optical lenses is effective in controlling myopia progression in children and adolescents.

Prevention of myopia progression using orthokeratology

The prevalence of myopia in children and juveniles has increased significantly in Korea and worldwide; in particular, the rates of myopia and high myopia in East Asia have grown rapidly. Myopia is easily corrected with spectacles or contact lenses. However, as children grow and mature, myopia can progress irreversibly and lead to vision-threatening complications. Thus, the prevention of myopia progression is an essential treatment goal. Many treatment strategies are being employed, including atropine eyedrops, specialized glasses, and orthokeratology (Ortho-K) lenses. Ortho-K is an effective treatment in managing myopia progression by lowering the rate of increase in refractive error and axial length. In this article, we review Ortho-K as a treatment for myopia progression, its history, mechanism, treatment regimen, and safety profile.

The correction of a hyperopic astigmatism with full-toric orthokeratology lenses. Clinical case

Orthokeratology has gained widespread clinical application in the last decade due to accumulated scientifi c data confi rming its effectiveness in inhibiting progressive myopia in children and adolescents. In cases of correction of other refractive errors, such as hypermetropia, mixed astigmatism, specialists inform patients about the possibilities of orthokeratology lenses (OKL) not often. This clinical case demonstrates the possibilities of customized, full-toric OKL to correct complex hyperopic astigmatism in an 11-year-old child. The patient was observed for several years with complex hyperopic astigmatism in ophthalmological clinics and followed the recommendations of specialists to use eyeglass correction. At the stage of transition from preschool to primary school, the child became shy of glasses and refused to wear them. In search of an alternative method of correction, parents sought advice in the special contact lens practice. The patient underwent a complete ophthalmological examination, including corneal topography. Taking into account the features of refraction and the shape of the cornea, the wishes of the child and parents, we have chosen customized orthokeratology lenses (OKL) with a fully toric design (full-toric) as method of correction. The OKL parameters were calculated by using the RGP Designer program. The lenses were made by OKVision Laboratory (Moscow). The fi tting of customized OKL allowed us to solve several tasks at once: the correction of complex hyperopic astigmatism and the freedom from using correction tools in the daytime. Despite the fact that orthokeratology is not the fi rst-line choice for optical correction of hyperopia, in some cases the method may become the only alternative to glasses and soft contact lenses

The efficacy of a device-based approach to microorganism disinfection and protein removal for orthokeratology lenses in varied clinical circumstances

PurposeRigidCare is an electrolysis-based device that recently obtained approval from the US’s FDA to sterilise microorganisms and remove proteins for orthokeratology (O-K) lenses. The study was conducted to investigate the device’s performance in varied clinical circumstances. MethodsTrial lenses and private lenses were employed by O-K lens wearers from five hospitals for an evaluation of disinfection and sterilisation and an assessment of protein removal, respectively. Menicon multipurpose solution and protein remover were selected for use with the control group. Following the instructions, pre-cleaning lens samples, post-cleaning lens samples and residual solution samples of trial lenses of the experimental and control groups were collected for microorganism examinations by an experienced third-party testing organisation. The levels of protein deposition for these two approaches were rated by senior O-K experts. Categorical variables were analysed using statistical tests, such as the chi-squared test and Fisher’s exact test. ResultsThe microbial positive rate detected from the pre-cleaning and post-cleaning lens samples and the residual solution of the trial lenses for the experimental and control group was 4/76 vs 1/74 (P = 0.37), 1/76 vs 0/74 (P = 1.00) and 0/76 vs 8/74 (P = 0.006), respectively. Following protein removal, the experimental group exhibited a significantly higher overall proportion of lenses rated as ‘clean’ or with a ‘mild deposit’ (96.4 %, 79/82) compared to the control group (85.7 %, 66/77), with a significant difference (P < 0.05). ConclusionThis multi-center study demonstrated that RigidCare exhibited superior efficacy in disinfection, sterilisation and protein removal as compared to Menicon multipurpose solution and protein remover.

Evaluation of Indicators of the Optical System and Hydrodynamics of Eyes With Myopia in the Treatment of Orthokeratological Lenses

Purpose. To study the features of changes in the parameters of the optical system and hydrodynamics of eyes with myopia during treatment with orthokeratological lenses. 80 patients (160 eyes) with mild myopia were examined — 30 patients (60 eyes) and 50 patients (100 eyes) with moderate myopia before and after treatment with orthokeratological lenses. Research methods. Visometry, autorefractometry, ophthalmometry, biometry, keratotopography, determination of accommodation indicators (AOA, ZOA) and hydrodynamics of the eyes. Results: It was revealed after the use of orthokeratological lenses in the night mode, a significant decrease in the true vg d (Po) and an increase in the coefficient of ease of outflow (C) with the activation of accommodation indicators — AOA and ZOA, contributing to a decrease in the degree of myopia and an increase in uncorrected visual acuity. Conclusion: One of the factors of the effectiveness of the treatment of myopia with orthokeratological lenses are the indicators of the hydrodynamics of the eyes and the strengthening of the functions of the accommodation apparatus — an increase in AOA and ZOA.

Alterations of conjunctival microbiota associated with orthokeratology lens wearing in myopic children

BackgroundOrthokeratology (OK) lens wear increases the risk of bacterial infection, but little is known about the microbiota of the conjunctival sac in myopic children wearing OK lenses. This study aimed to investigate the changes of conjunctival microbiota in children after treatment with OK lenses using 16 S rDNA sequencing.MethodsTwenty-eight myopic children who had been continuously wearing OK lenses for 12 to 13 months were enrolled in this prospective study. Twenty-two gender- and age-matched myopic children who had not worn OK lenses or discontinued OK lens wear at least 1 year ago were recruited as controls. Conjunctival swabs from each participant were collected for exploration of the microbiota profiles, targeting the V3–V4 regions of the 16 S rRNA gene by MiSeq sequencing. The differences in the microbial community structure and diversity were also compared between groups.ResultsThe bacterial alpha diversity indices in the OK lens group were not different from those in the non-wearer group (P > 0.05, Wilcoxon test), while beta diversity examined using principle coordinate analysis of unweighted UniFrac divided the two groups into different clusters. Proteobacteria, Bacteroidetes, and Firmicutes were the abundant phyla in the conjunctival sac microbiota in both groups (P < 0.05, Mann–Whitney U test). Among children in the OK lens group, the Linear discriminant analysis Effect Size identified the compositional changes in OK lens-associated bacteria. Key functional genera such as Blautia, Parasutterella, and Muribaculum were enriched, whereas Brevundimonas, Acinetobacter, Proteus, and Agathobacter decreased significantly (P < 0.05, Mann–Whitney U test). Phylogenetic investigation of communities by reconstruction of unobserved states also showed altered bacterial metabolic pathways in OK lens-associated microbiota. Moreover, using receiver operating characteristic curves, Brevundimonas, Acinetobacter, Proteus, and Agathobacter alone (the area under the curve was all > 0.7500) or in combination (the area under the curve was 0.9058) were revealed to discriminate OK lens wearers from controls.ConclusionsThe relative abundance of the microbial community in the conjunctival sac of myopic children can alter after OK lens wear. Brevundimonas, Acinetobacter, Proteus, and Agathobacter may be candidate biomarkers to distinguish between OK lens wearers and non-wearers.

Effect of myopia-control lenses on central and peripheral visual performance in myopic children.

To evaluate the short-term effects of three myopia-control lenses, which impose peripheral myopic defocus while providing clear central vision, on central and peripheral visual performance in myopic children. Twenty-one myopic children were enrolled in the study. Central visual performance was assessed using the quick contrast sensitivity function. Peripheral visual performance was evaluated by measuring peripheral contrast threshold and global motion perception, while subjects maintained fixation through the central portion of the lens. Single-vision spectacle lenses (SVL), spectacle lenses with highly aspherical lenslets (HAL) and defocus-incorporated soft contact (DISC) lenses were evaluated in random order, followed by orthokeratology (OK) lenses. All tests were performed monocularly on the right eye. The area under the log contrast sensitivity function (AULCSF) with DISC lenses was lower than that with SVL (1.14 vs. 1.40, p < 0.001) and HAL (1.14 vs. 1.33, p = 0.001). HAL increased the temporal visual field contrast threshold compared with OK lenses (p = 0.04), and OK lenses decreased the superior visual field contrast threshold compared with that of SVL (p = 0.04) and HAL (p = 0.005). HAL also increased the peripheral coherence threshold for identifying the contraction movement compared with OK lenses (p = 0.01). The short-term use of these optical interventions for myopia control exhibited measurable differences in central and peripheral visual performance. Relevant attention could be paid to these differences, especially when children switch to different treatments. DISC lenses exhibited worse central contrast sensitivity than SVL and HAL. Imposing peripheral defocus signals did not affect children's peripheral visual performance compared with SVL. However, considering the poorer peripheral visual performance provided by HAL, OK lenses are recommended for children if there are specific demands for global scene recognition and motion perception.

Increased hydrophilicity and anti-fouling effect of orthokeratology lenses coated with NVP and PEGMA by plasma-enhanced chemical vapor deposition

Increased hydrophilicity and anti-fouling effect of orthokeratology lenses coated with NVP and PEGMA by plasma-enhanced chemical vapor deposition

The alterations in ocular biometric parameters following short-term discontinuation of long-term orthokeratology and prior to subsequent lens fitting: a preliminary study

Purpose To investigate the alterations in biometric parameters among Chinese adolescents over an extended period of wearing orthokeratology lenses, as well as the subsequent changes after a one-month cessation of lens usage prior to the secondary lens fitting. Methods Twenty-four myopic patients aged 7–14 were enrolled in this 37-month prospective observational study. Ocular biometric parameters were measured in the study. Ocular biometric parameters were assessed, and the utilization of Generalized Estimating Equations (GEE) was employed in the analysis to address the correlation between the two eyes of each participant. Results The axial length (AL) increased by 0.55 mm after 36 months of lens wearing and further increased to 0.62 mm at the 37-month follow-up compared to the initial measurement. The differences in AL elongation per month between the 37-month time point and the 12-, 24-, and 36-month marks of lens wearing were found to be statistically significant (p12-month = 0.001; p24-month = 0.003; p36-month = 0.001). Following the cessation of lens wear for 1 month, there was no significant complete recovery observed in the flat and steep keratometry values. However, the intraocular pressure and anterior chamber depth returned to their baseline levels. Conclusions The AL elongation undergoes alterations during temporary discontinuation of lenses, with the flat and steep keratometry measurements remaining significantly flatter compared to the baseline. However, the intraocular pressure and anterior chamber depth return to their initial levels after one month of lens cessation.

Efficacy of small back optic zone design on myopia control for corneal refractive therapy (CRT): a one-year prospective cohort study

BackgroundTo investigate the control effect on the axial length elongation using corneal refractive therapy (CRT) with different optical zone diameters (BOZDs). We also sought to compare the difference in higher-order aberrations (HOAs), treatment zone (TZ) size and Zernike defocus coefficient with different BOZDs and seek the optimal parameter for predicting axial elongation.MethodsThis prospective cohort study included 7- to 14-year-olds fitted with orthokeratology (ortho-K) lenses of 5-mm (5-mm group) or 6-mm BOZD (6-mm group). Axial length (AL), corneal topography, HOAs and Zernike defocus coefficient were obtained at baseline, and 1, 3, 6, 9 and 12 months follow-up visits. Multivariate regression analyses were used to explore the association between AL change and ocular biometric parameters. Receiver operating characteristic (ROC) curve analysis was used to determine the best diagnostic value for AL change in ocular biometric parameters.ResultsIn total, 301 participants completed the one-year follow-up. The mean AL change in the 5-mm group (0.13 ± 0.18 mm) was less than that in the 6-mm group (0.27 ± 0.15 mm) at the 12 months visit. The TZ size and decentration were smaller, while the Zernike defocus coefficient and HOAs were higher in the 5-mm group (all P < 0.05). Older age and smaller TZ size were protective factors against AL elongation in multiple regression. In predicting AL elongation, TZ diameter yielded an area under the ROC curve of 0.684 with a cut-off value of 3.82 mm.ConclusionThe 5-mm group showed 0.14 mm (51.8%) less axial elongation than the 6-mm group. The 5-mm BOZD produced a smaller TZ size, higher Zernike defocus coefficient and higher HOA after reshaping of the cornea. TZ size was the best predictor of AL elongation. TZ diameter less than 3.82 mm may lead to AL elongation less than 0.2 mm in one year.

Orthokeratology combined with spectacles in moderate to high myopia adolescents

PurposeWearing ortho-k lenses overnight may not fully correct their daytime refractory errors of adolescents with moderate to high myopia. There are three common ways to deal with the daytime residual refractive error (RRE): 1) wearing spectacles to correct the RRE; 2) wear ortho-k lenses during the daytime instead of overnight.; 3) not correcting the residual refractive error. According to previous laboratory studies, myopic peripheral refraction is associated with better myopic control. This study had two aims:1) to compare relative peripheral refractive error (RPRE) among these ways after one-month stabilization; 2) to assess the axial length changes over 2 years of ortho-k lens overnight wear combined with spectacle glasses. MethodsThis was a prospective, non-controlled, non-randomized, observational study in which a total of 27 subjects (20 females, 7 males, mean age 12.48 ± 2.23Y) with spherical equivalent refractive error from −5.00 to −8.25D were enrolled. All participants in the study wore orthokeratology (ortho-k) lenses overnight for a minimum of one month. Subsequently, their peripheral refractive error (PRE) was assessed using an open-field autorefractor. During the assessment, the participants underwent three conditions in a random order in a same morning: 1) unaided eye after orthokeratology (referred to as the Unaided-eye condition), 2) wearing glasses to correct any remaining refractive errors after orthokeratology (referred to as the Spec-RE condition), and 3) wearing ortho-k lenses during the daytime (referred to as the Continuous OK wear condition). After testing, all subjects were instructed to wear ortho-k lenses overnight and glasses during the daytime to correct their RRE for the next 2 years, during which time the progression of their axial length was followed up. Results1) RPRE in either Unaided-eye or Spec-RE condition subjects were significantly more myopic than those in the Continuous OK wear condition. 2) No difference in RPRE was seen between Unaided-eye and Spec-RE conditions. 3) Axial length growth was 0.05 ± 0.20 mm and 0.17 ± 0.32 mm (mean ± standard deviation) at 1-year and 2-year follow-ups after the initial visit, respectively, which were comparable to mild myopia patients after orthokeratology. 4) After orthokeratology, axial length change had negative correlation with the initial age (p = 0.001, r = −0.616) and residual diopter (p = 0.022). ConclusionsFor myopes above refraction < −5.00D, wearing Ortho-k lenses overnight and glasses to correct the RRE in the daytime is recommended to ensure good visual quality and have more myopic RPRE for potential myopia control.

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

BackgroundTo compare the changes in corneal biomechanics after orthokeratology (OK) lens and Defocus Incorporated Soft Contact (DISC) lens treatment. MethodsOf 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. ResultsThroughout 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). ConclusionsThe 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.