Effect of Lens Deviation on Peripheral Defocus and Optic Quality in Adolescents With Moderate and Severe Myopia.

OBJECTIVES: The aim of this study was to analyze the effects of lens deviation on peripheral defocus and optic quality in adolescents with moderate and severe myopia. METHODS: This prospective study enrolled 81 children (81 eyes). The spherical equivalent was -5.0≤SE≤-6.0 diopter. The participants were divided into two subgroups based on their eccentricity (inferior temporal) after wearing the lenses for 12 months. Between them, the low eccentric subgroup (A) had a total eccentric distance of less than 0.5 mm, and the moderate and severe eccentric subgroup (B) had a total eccentric distance of ≥0.5 mm. Peripheral defocus and eccentricity were measured before and after wearing the lenses, and the Spearman test was used to compare the parameters. RESULTS: Parameters such as the total peripheral defocus (TRDV) were significantly lower in subgroup B than in subgroup A after 12 months of orthokeratology lens usage. The axial length growth (ΔAL) in subgroup A was higher than that in subgroup B. Axial length growth, TRDV, and other parameters were significantly associated with eccentricity. The modulation transfer function cutoff and Strehl ratio were also significantly associated with eccentricity. CONCLUSIONS: Greater eccentricity within a certain range can induce greater periretinal defocus and improve the ΔAL.

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.

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

PURPOSE: To investigate axial elongation (AE) and changes in relative peripheral refraction (RPR) in anisomyopic children undergoing orthokeratology (ortho-k). METHODS: Bilateral anisomyopic children, 7-12 years of age, were treated with ortho-k. Axial length (AL) and RPR, from 30° nasal (N30°) to 30° temporal (T30°), were measured at baseline and every 6 months over the study period. AE, changes in RPR and changes in the interocular AL difference were determined over time. RESULTS: Twenty-six of the 33 subjects completed the 2-year study. The AE of the higher myopic (HM) eyes (at least 1.50 D more myopia than the other eye) (0.26 ± 0.29 mm) was significantly smaller than for the less myopic (LM) eyes (0.50 ± 0.27 mm; p = 0.003), leading to a reduction in the interocular difference in AL (p = 0.001). Baseline RPR measurements in the HM eyes were relatively more hyperopic at T30°, N20° and N30° (p ≤ 0.02) and greater myopic shifts were observed at T20° (p < 0.001), T30° (p < 0.001), N20° (p = 0.02) and N30° (p = 0.01) after lens wear. After 2 years of ortho-k lens wear, temporal-nasal asymmetry increased significantly, being more myopic at the temporal locations in both eyes (p < 0.001), while AE was associated with the change in RPR at N20° (ß = 0.134, p = 0.01). The interocular difference in AE was also positively associated with the interocular difference in RPR change at N30° (ß = 0.111, p = 0.02). CONCLUSIONS: Ortho-k slowed AE in bilateral anisomyopia, with slower growth in the HM eyes leading to a reduction in interocular AL differences. After ortho-k, RPR changed from hyperopia to myopia, with greater changes induced in the HM eyes, and slower AE was associated with a more myopic shift in RPR, especially in the nasal field of both eyes.

Changes in the Objective Vision Quality of Adolescents in a Mesopic Visual Environment After Wearing Orthokeratology Lenses: A Prospective Study.

PURPOSE: This study aimed to investigate changes in objective vision quality in mesopic environments in teenagers with myopia after wearing orthokeratology (OK) lenses. METHODS: This prospective clinical study included 45 patients (80 eyes) who received OK lenses at the First Affiliated Hospital of Jinan University from March 2021 to September 2021. An Optical Path Difference-Scan III refractive power/corneal analyzer was used to determine the corneal topographic parameters (corneal e, corneal Q, surface asymmetry index (SAI), and surface regularity index (SRI)), higher-order aberrations (HOAs), axial length (AL) change, lens decentration, induced astigmatism, target power, and Strehl ratio (SR) in a mesopic visual environment after wearing OK lenses for 6 months. In addition, corneal morphological parameters, HOAs, and SR were analyzed in a mesopic visual environment. Finally, we investigated the correlations among corneal morphology, HOAs, AL change, lens decentration, induced astigmatism, and SR. RESULTS: The SAI value was significantly higher ( P <0.01), and the corneal e was significantly lower ( P <0.01), in a mesopic visual environment after wearing OK lenses for 1 week than baseline. A significant increase was observed in total HOAs and spherical aberrations, compared with before the OK lenses were worn ( P <0.01). In addition, SR in the mesopic visual environment decreased significantly after wearing the lenses ( P <0.01). No significant differences were observed ( P >0.05) among the 1-week, 1-month, 3-month, and 6-month follow-up findings. After 6 months, AL and lens decentration did not differ significantly compared with before ( P >0.05), whereas induced astigmatism significantly increased ( P <0.05). Negative correlations were observed between corneal Q, SAI, SRI, HOAs, induced astigmatism, and SR, and positive correlations were found between corneal e, AL change, lens decentration, and SR, after wearing OK lenses. KEY POINTS: • Wearing orthokeratology lenses significantly altered corneal morphology and HOAs in myopic teenagers within 1 week. • The changes that we observed in the eyes of adolescents with myopia after wearing orthokeratology lenses decreased vision quality in mesopic environments. • Strehl ratio is significantly correlated with multiple parameters, including HOAs, AL change, and lens decentration. CONCLUSIONS: In teenagers with myopia wearing OK lenses, significant changes in vision quality and corneal morphology were observed, leading to increased aberrations and affecting optical imaging quality. Furthermore, SR is significantly correlated with multiple parameters, including HOAs, AL change, and lens decentration. REGISTRATION NUMBER: This study is registered with the United States Clinical Trials Registry under registration number NCT04929119.

Three optical intervention methods for low myopia control in children: a one-year follow-up study.

OBJECTIVE: This study aimed to compare the one-year efficacy of myopia prevention and control using three optical intervention methods - single vision lens (SVL), high aspherical lenticule (HAL), and orthokeratology (OK) lens - in children with low myopia. METHODS: A cohort of 150 children aged 7-13 years with low myopia was recruited and divided into three groups: SVL (n = 50), HAL (n = 50), and OK lens group (n = 50), based on their preference for glasses. Follow-up assessments were carried out over one year, focusing on data from the right eye for statistical analysis. Baseline characteristics such as gender, age, axial length (AL), spherical equivalent refractive error (SER), flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), white-to-white corneal diameter (WTW), and non-contact tonometry (NCT) measurements were gathered and compared among the three groups before any intervention. Changes in AL growth after 1 year of intervention were assessed across the three groups. Subsequently, the AL growth control rates between the HAL and OK lens groups were compared, with the SVL group serving as the reference standard. RESULTS: The study found no statistically significant variances in baseline characteristics (gender, age, SER, AL, K1, K2, WTW, and NCT) among the SVL, HAL, and OK lens groups (all p > 0.05). Following a one-year intervention, AL growth rates were as follows: HAL group (0.163 ± 0.113 mm) < OK lens group (0.280 ± 0.170 mm) < SVL group (0.516 ± 0.190 mm), with statistically significant disparities (p < 0.05). The HAL group demonstrated a higher 1-year AL growth control rate (68.41%) compared to the OK lens group (45.74%) for children aged 7-13 with low myopia, with a statistically significant differences (p < 0.001). And there was significant difference in the SER change between SVL group and HAL group (p < 0.001). CONCLUSION: Compared to SVL, HAL and OK lens are more effective in controlling axial growth in mild myopia. Specifically, HAL maybe shows superior outcomes in both preventive and corrective measures, also it needs to be supported by more studies from randomized controlled experiments.

Optical coherence tomography angiography reveals macular microvascular changes in myopic adolescents following orthokeratology lens wear.

BACKGROUND: This study aimed to investigate the 6-month effects of wearing orthokeratology (OK) lenses on the retina vessel density (VD), vessel diameter index (VDI), and foveal avascular zone (FAZ) of myopia children using optical coherence tomography angiography, and to further investigate the underlying mechanisms of Orthokeratology in myopia control. METHODS: Sixty-two eyes form 62 subjects were included in the study. Baseline and 6-month measurements of axial length (AL), anterior chamber depth (ACD), FAZ area, FAZ perimeter, FAZ circularity, vessel density (VD) and VDI from both the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were obtained. RESULTS: The mean age of the participants was 11.02 years (range: 8 years to 15 years), with 41.9% males and 58.1% females. Six months after orthokeratology, ACD decreased significantly, and AL remain unchanged. SCP-VD and DCP-VD significantly increased after treatment without obvious change of VDI, and FAZ parameters remained unchanged. During follow-up period, SCP-VD increased in all subgroups especially in mild myopia group, and DCP-VD increased significantly in all subgroups except for the group 8-10 years. CONCLUSION: After the 6-month treatment of orthokeratology in myopia children, the macular microvasculature changed significantly. We observed a significant increase of vessel densities in both SCP and DCP without obvious effect on vascular morphology. The changes of DCP-VD tended to be more sensitive in the elder subgroup, and the efficacy of orthokeratology might be greater in mild myopia group. OCT-A may provide additional information on myopia progression and the mechanisms of controlling myopia with OK lens treatment.

Efficacy and safety of 0.01% atropine combined with orthokeratology lens in delaying juvenile myopia: An observational study.

It aims to study the efficacy and safety of low-concentration Atropine combined with orthokeratology (OK) lens in delaying juvenile myopia. This is a prospective study, 172 adolescents aged 8 to 12 years who were admitted to the diopter department of Hengshui People Hospital from April 2021 to May 2022 were selected. According to the equivalent spherical diopter measured at the time of initial diagnosis, myopic patients were randomly divided into low myopia group (group A) and moderate myopia group (group B). At the same time, according to the different treatment methods, the patients were divided into the group wearing frame glasses alone (group c), the group wearing frame glasses with low-concentration Atropine (group d), the group wearing corneal shaping glasses alone at night (group e), and the group wearing corneal shaping glasses at night with low-concentration Atropine (group f). The control effect of myopia development and axial elongation in group f was better than that in groups d and e (P < .05). The effect of controlling myopia development and axial elongation in group f is with P > .05. The probability of postoperative adverse reactions in group f was lower and lower than that in the other groups. Low-concentration atropine combined with OK lens could effectively delay the development of juvenile myopia, and had a high safety. Low-concentration of Atropine would not have a significant impact on the basic tear secretion and tear film stability. Nightwear of OK lens also had no significant impact, but it would significantly reduce the tear film rupture time in the first 3 months, and at the same time, the tear film rupture time would be the same after 6 months as before treatment.

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

PURPOSE: This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects. METHOD: 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. RESULTS: 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. CONCLUSIONS: 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.

Analysis of Treatment Discontinuation in Orthokeratology: Studying Efficacy, Safety, and Patient Adherence Over Six Months.

PURPOSE: This study aimed to evaluate the efficacy, safety, and participant compliance of orthokeratology treatment for the correction of myopic refractive errors over a six-month prospective study and to define the potential reasons for early treatment discontinuation. METHODS: A total of 32 participants with low-to-moderate myopia were fitted with the spherical model of corneal refractive therapy (CRT) orthokeratology lenses (Paragon Vision Sciences) and followed over six months, with specific attention to alterations in refractive error, corneal topography, and epithelial thickness. Concurrently, participant feedback and reasons for any treatment discontinuation were documented. RESULTS: Significant changes in refractive error and in corneal topography were observed, with approximately 50% of the refractive error being corrected on the first night of use and 100% by the first two weeks ( P <0.001). Central epithelial thickness experienced substantial thinning, reducing to 15.65±4.49 µm (67.38%) ( P <0.001) after 6 months of lens use. Six participants withdrew from this study for varied reasons, including unmet visual expectations and difficulty adhering to the lens-wearing regimen. Notably, the dropout group exhibited higher baseline low-order aberrations and less prolate corneas than those who persisted with the treatment ( P <0.05). CONCLUSIONS: Orthokeratology with CRT is efficacious and safe for the correction of low-to-moderate myopia in adults, but a portion of patients discontinue the treatment in the first 6 months of contact lens wear. Special care should be taken when recommending orthokeratology in patients with higher levels of myopia and corneas with less prolate shape, providing more realistic expectations and even changing to dual axis or more sophisticated designs.

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

BACKGROUND: This meta-analysis reviews the evidence for the risks and benefits associated with orthokeratology (OK) treatment compared with other methods of myopia control in children and adults. METHODS: A systematic search of Cochrane Central Register of Controlled Trials, Pubmed, Embase and Ovid was conducted from database inception to 22nd August 2021. Studies that reported on risks, visual and ocular biometric effects of OK in patients > 5 years of age with myopia (- 0.75 to - 6.00D) were included. Main outcomes are change in axial length and any adverse event. RESULTS: Fourty-five papers were included in this systematic review and meta-analysis. The quality of data was variable and of moderate certainty, and selection bias likely skewed the results towards a relative benefit for OK. The rate of axial elongation in children was lower for OK treatment compared to other treatment modalities at one year (MD - 0.16 mm, 95% CI - 0.25 to - 0.07). Rate of change in axial length in children rebounded after OK discontinuation compared to participants who continued treatment (MD 0.10 mm, 95% CI 0.06 to 0.14). Adults and children wearing OK were up to 3.79 times more likely to experience an adverse event when compared with conventional contact lenses (OR 3.79, 95% CI 1.24 to ll.), though this evidence base is underdeveloped and requires additional well-designed studies for substantial conclusions to be drawn. CONCLUSIONS: OK arrests myopia progression while in use, however, there remain unanswered questions about the optimal duration of treatment, discontinuation effects and long-term risk for adverse events.

[The role of peripheral retinal defocus in myopia progression].

The increasing incidence of myopia has become a global public health concern. Exploring the mechanisms underlying the onset and progression of myopia is crucial for prevention and control. This paper reviews the role of peripheral retinal defocus mechanisms in the development of myopia, with particular emphasis on the interaction between accommodation lag and peripheral retinal defocus, as well as the impact of optical intervention on myopia control effectiveness. In recent years, researchers have developed various optical tools for myopia prevention and control based on the peripheral retinal defocus theory, such as peripheral defocus spectacle lenses, orthokeratology lenses, and peripheral defocus soft contact lenses. This paper aims to provide clinicians with the latest research findings to deepen their understanding of the mechanisms involved in myopia development and to guide the future development and clinical application of myopia prevention and control products.

Artificial Intelligence-Assisted Prescription Determination for Orthokeratology Lens Fitting: From Algorithm to Clinical Practice.

OBJECTIVES: To explore the potential of artificial intelligence (AI) to assist prescription determination for orthokeratology (OK) lenses. METHODS: Artificial intelligence algorithm development followed by a real-world trial. A total of 11,502 OK lenses fitting records collected from seven clinical environments covering major brands. Records were randomly divided in a three-way data split. Cross-validation was used to identify the most accurate algorithm, followed by an evaluation using an independent test data set. An online AI-assisted system was implemented and assessed in a real-world trial involving four junior and three senior clinicians. RESULTS: The primary outcome measure was the algorithm's accuracy (ACC). The ACC of the best performance of algorithms to predict the targeted reduction amplitude, lens diameter, and alignment curve of the prescription was 0.80, 0.82, and 0.83, respectively. With the assistance of the AI system, the number of trials required to determine the final prescription significantly decreased for six of the seven participating clinicians (all P <0.01). This reduction was more significant among junior clinicians compared with consultants (0.76±0.60 vs. 0.32±0.60, P <0.001). Junior clinicians achieved clinical outcomes comparable to their seniors, as 93.96% (140/149) and 94.44% (119/126), respectively, of the eyes fitted achieved unaided visual acuity no worse than 0.8 ( P =0.864). CONCLUSIONS: AI can improve prescription efficiency and reduce discrepancies in clinical outcomes among clinicians with differing levels of experience. Embedment of AI in practice should ultimately help lessen the medical burden and improve service quality for myopia boom emerging worldwide.

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.

The Impact of Back Optic Zone Design in Orthokeratology on Visual Performance.

Purpose: To evaluate the visual performance in adolescents undergoing orthokeratology (OrthoK) treatment with two different optical zone diameters (OZDs). Methods: This randomized, double-masked, self-controlled prospective study was conducted at Tianjin Eye Hospital (Tianjin, China) in June 2022. Thirty-six eligible schoolchildren were enrolled and fitted with corneal refractive therapy lenses with two sizes of OZDs (5 mm [5OZ] and 6 mm [6OZ]). Each participant was randomized to wear the 5OZ in one eye and the 6OZ in the contralateral eye. Subjective visual quality was assessed using visual acuity, refraction, contrast sensitivity function, and visual symptoms, and the objective optical quality was assessed using ocular higher order aberrations (HOAs) and modulation transfer function (MTF). Results: Thirty-five myopic children completed a 1-month follow-up visit. The 5OZ lens induced significantly smaller treatment zone diameters than the 6OZ lens (P < 0.001). Subjective visual quality did not differ significantly between the two groups. Compared to baseline, aberrations of Z40, coma-like, spherical-like, and total HOAs in both groups increased significantly (P < 0.05). For the 3-mm pupils, spherical aberration in the 5OZ group was significantly higher than that in the 6OZ group (P < 0.05). The MTF value of the 6OZ group was significantly higher than that of 5OZ group for 0.3 and 1.5 cycles per degree for the 3-mm pupils (P = 0.006 and P = 0.026, respectively). However, HOAs or MTF did not differ significantly between the two groups for the 5-mm pupils. Conclusions: The difference induced by varying OZD was significant only in the smaller pupil condition. The selection of OZD in OrthoK designs in real-world patient management should be done while considering individual pupil size. Translational Relevance: This study revealed that the objective visual quality of small OZD lenses was only slightly affected for the small pupil size.

Effectiveness of orthokeratology and myopia control spectacles in a real-world setting in China.

OBJECTIVE: To compare the effectiveness of myopia control in Chinese children, who had been wearing either orthokeratology (ortho-k) lenses or myopia control spectacles (MCS) for one year. METHODS: Relevant data were retrieved from 212 patients, with baseline myopia of -5.00 to -0.75 D, astigmatism ≤ 1.50 D, who had been undergoing myopia control treatment with either ortho-k (Euclid (OK1) or CRT (OK2)) or MCS (Stellest (MCS1) or DIMS (MCS2)) for at least one year. Myopia control effectiveness among the four groups was compared based on the change in spherical equivalent refraction (SER) (for the spectacle groups) and axial length (AL) (for all groups). Data retrieved, from the right eye only, included best corrected visual acuity (BCVA), SER, and AL at both the initial clinic visit (baseline) and the one-year visit was analysed. RESULTS: Although no significant differences in gender, cylindrical power, or BCVA were observed at the baseline visit (P > 0.05), there were significant differences in baseline age, myopia, and AL among the four groups (P < 0.05). No significant difference in axial elongation (AE) was found among the four groups after one year of treatment (P = 0.49). AE, adjusted for baseline age and spherical power, were 0.19 ± 0.15, 0.18 ± 0.14, 0.19 ± 0.19, 0.20 ± 0.18 mm for OK1, OK2, MCS1, MCS2, respectively. Only age was a significantly factor associated with AE and SER increase (P < 0.05), with negative associations between AE and age in all groups and positive association between SER increase and baseline age in the spectacle groups observed. CONCLUSION: Both brands of ortho-k lenses and MCS had similar myopia control effectiveness for mild to moderate myopic children treated in a real-world setting in China. Average AE in one year ranged from 0.18 to 0.20 mm, comparable to previous reports on myopia control using ortho-k.

The relationship between accommodative and binocular function with myopia progression in myopic children undergoing orthokeratology.

PURPOSE: To determine the relationship between changes in accommodative and binocular function with myopia progression in myopic children over a two-year follow-up period, and to determine when changes in visual functions stabilized after switching from spectacles to orthokeratology (Ortho-K). METHODS: This prospective, self-controlled study followed thirty-six participants (aged 8-14 years) for two years after they switched from spectacles to Ortho-K. Accommodative and binocular function were assessed prior to and 1, 3, 6, 12, 18 and 24 months after commencing Ortho-K. Measurements included accommodative amplitude, accommodative response, accommodative facility, accommodative convergence/accommodation (AC/A), ocular alignment, positive relative accommodation (PRA), negative relative accommodation (NRA), horizontal vergence range, reading ability and stereoacuity. Myopia progression was quantified by the change in axial length. RESULTS: Ocular alignment, monocular and binocular accommodative facility, and PRA stabilized after 1 month. The distance blur point in the convergence range, the distance break and recovery point in the divergence range, accommodative amplitude, calculated AC/A, stereoacuity and reading ability stabilized within 6 months. After two years of Ortho-K, NRA significantly increased (p = 0.044), while it showed no significant difference after one-year of lens wear (p = 0.49). The distance break point in the convergence range showed no significant difference (p = 0.20), but significantly decreased after one-year (p = 0.005). There were no significant correlations between the change in axial length with changes in accommodative or binocular function (p > 0.05). CONCLUSION: Accommodative and binocular function changed significantly after switching from spectacles to Ortho-K and most of the parameters stabilized within the first 6 months. There was no association between the change in accommodative or binocular function and myopia progression.

In vivo assessment of human corneal epithelial cells in orthokeratology lens wearers: A pilot study.

SIGNIFICANCE: Central corneal epithelial thinning associated with midperipheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet, the cellular mechanism governing the regional change in refractive power remains elusive. PURPOSE: This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers. METHODS: A new human prototype of a polarization-dependent optical coherence microscope was developed to enable noncontact and noninvasive in vivo imaging of corneal epithelial cells in ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and midperipheral corneal locations in four ortho-k wearers and four spectacle wearers serving as controls. RESULTS: Polarization-dependent optical coherence microscope achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view of 0.5 × 0.5 mm 2 with an isotropic resolution of ~2.2 mm. The central epithelial thinning and midperipheral epithelial thickening were consistent across all ortho-k wearers. However, the inconsistency in their regional epithelial cell density highlighted a great variability in individual response to ortho-k treatment. There was no strong correlation between epithelial thickness and cell density, especially at the midperipheral cornea, in ortho-k participants. CONCLUSIONS: This study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cells before and during ortho-k treatment to identify factors governing individual response to ortho-k treatment and ultimately inform the dynamics of epithelial cells taking place during the ortho-k treatment.

Association Between Serratia marcescens Contamination and Hygiene Compliance in Orthokeratology.

BACKGROUND/AIM: Given the characteristics of Serratia marcescens (S. marcescens), this study aimed at investigating its presence in the hands and contact lens cases of orthokeratology wearers, along with the status of bacterial contamination. PATIENTS AND METHODS: The 39 patients received the questionnaires about the background of orthokeratology and hygiene habits. A total of 39 contact lens cases and 39 hand samples from the patients were collected at Show Chwan Memorial Hospital from June to August in 2020 and sent to National Chung Cheng University for DNA extraction and PCR identification. RESULTS: The results indicated a detection rate of 5.13% for S. marcescens in the contact lens cases and 12.82% in the hand samples. Additionally, 66.67% of contact lens case samples and 30.77% of hand samples found positive for 16s bacterial amplicons. The relationship between hand contamination and the duration of contact lens usage were revealed for both S. marcescens (p=0.021) and 16s bacterial amplicons (p=0.048). CONCLUSION: The results indicated that hand hygiene is more critical than focusing on contact lens hygiene when it comes to preventing S. marcescens infections. Nevertheless, both proper hand and contact lens hygiene practices can reduce the detection of bacterial eye pathogens, especially a common intestinal bacterium.

Redistribution of Epithelium and Stroma and Their Relationship With Corneal Curvature After 1-Month Cessation of Overnight Orthokeratology.

OBJECTIVES: To investigate the changes in the thickness of epithelium and stroma and their relationship with corneal curvature following the cessation of overnight orthokeratology for a period of 1 month. METHODS: This prospective study consecutively included 20 juveniles (20 right eyes) who had undergone overnight orthokeratology for a minimum of one year and were willing to discontinue the treatment. The study measured and compared epithelial and corneal curvature using optical coherence tomography and Medmont topographer at the first day of cessation and 1 month after cessation. In addition, changes in uncorrected visual acuity and refractive error before and after the cessation of the treatment were analyzed. RESULTS: The study found a significant increase in the thickness of the epithelium in the central 2-mm area after the cessation of the treatment (t = -4.807, P <0.001). Moreover, the stroma in the paracentral area (2-5 mm) and peripheral area (5-6 mm) showed a general thinning trend ( P =0.016, P =0.016). Regarding the correlation analysis, the change in central epithelial thickness (ΔCET) was significantly correlated with the change in paracentral corneal curvature (ΔPCCC) (r=0.610, P =0.007) and the change in peripheral corneal curvature (ΔPCC) (r=0.597, P =0.009). Similarly, the change in central stromal thickness (ΔCST) was significantly correlated with the change in central corneal curvature (ΔCCC) (r=0.500, P =0.035), ΔPCCC (r=0.700, P =0.001), and ΔPCC (r=0.635, P =0.005). CONCLUSIONS: The study found that the corneal remodeling induced by orthokeratology was reversible after the cessation of the treatment. Specifically, changes in the epithelium were found to be more prominent in the central area, while changes in the stroma were more pronounced in the paracentral and peripheral areas. In addition, the study established a significant correlation between central corneal remodeling and changes in curvature.

[Effect of corneal e-value on myopia control in children and adolescents with orthokeratology].

Objective: To investigate the influence of corneal e-value on the effectiveness of orthokeratology in controlling myopia in children and adolescents. Methods: A retrospective cohort study was conducted, involving the data from 1 563 myopic patients (1 563 eyes) who underwent orthokeratology at the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine from June 2015 to August 2021 and adhered to lens wear for at least 2 years. The cohort consisted of 737 males and 826 females with an average age of (10.84±2.13) years. Based on corneal e-value parameters obtained from corneal topography, patients were categorized into a low e-value group (n=425) and a high e-value group (n=1 138). Data on gender, age, parental myopia history, and baseline measures such as spherical equivalent (SE), axial length, and corneal e-value were collected. Differences in axial length change and corneal fluorescein staining rates were compared between the two groups at 1 and 2 years after the start of lens wear. A generalized linear mixed model was established with axial length change as the dependent variable to analyze the correlation between axial length change and baseline corneal e-value. Results: The initial age of the 1 563 myopic patients was (10.84±2.13) years, with a baseline SE of (-3.05±1.30) D. After 1 year of lens wear, the axial length change was (0.20±0.19) mm in the low e-value group and (0.24±0.20) mm in the high e-value group. After 2 years, the changes were (0.38±0.25) mm and (0.43±0.27) mm, respectively, with statistically significant differences (all P<0.05). The incidence of corneal staining after 1 year of lens wear was 9.2% (39/425) in the low e-value group and 14.1% (160/1 138) in the high e-value group. After 2 years, the rates were 15.8% (67/425) and 21.8% (248/1 138), respectively, with statistically significant differences (all P<0.05). After adjusting for parental myopia history, age, SE, and baseline axial length, the baseline corneal e-value was positively correlated with axial length change at 1 and 2 years after lens wear (all P<0.05). Conclusions: Corneal e-value is an independent factor influencing the effectiveness of orthokeratology in controlling myopia. A smaller corneal e-value is associated with slower axial length growth after orthokeratology, indicating better control of myopia in treated eyes.