Orthokeratology and high myopia

To report the effect of stopping orthokeratology (ortho-k) lens wear on the changes in refractive errors and axial elongation in a girl who has been wearing ortho-k lenses for myopic control for over 2 years. A girl with a history of fast myopic progression enrolled in ortho-k treatment when she was 6 years old. She switched to spectacle wear after receiving ortho-k treatment for 38 months and then switched back to ortho-k lens wear. Refractive errors and axial lengths were monitored for 8 months with ortho-k lens wear, followed by about 6½ months of lens discontinuation and spectacle wear, and finally another 6 months of resumed ortho-k lens wear. The residual refractive errors in the 8 months before discontinuation of ortho-k lens wear were not more than ±0.25 diopter (D) and -0.50 D in spherical and cylindrical powers, respectively, and the average increases in axial length were 0.02 mm (OD) and 0.03 mm (OS) per month. Myopia increased by 0.75 D (OD) and 1.25 D (OS) during the lens discontinuation period, with corresponding axial elongations of 0.06 mm (OD and OS) per month. No significant changes were observed in axial elongation or residual refractive errors during the 6-month period of resumed lens wear. When a child who had been wearing ortho-k lenses for myopic control for over 2 years ceased lens wear, small net amounts of axial elongation were observed during the subsequent months with spectacle wear. These changes took place at a faster rate relative to the ortho-k lens wear period. Ortho-k lens wear appeared to slow myopic progression for this child.

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.

Purpose: To investigate the cause of failure in the correction of childhood myopia using orthokeratologic (Ortho-K) lenses. Methods: The failure group was 29 patients who stopped wearing the lenses for various reasons, while the success group was 29 patients who bought lenses more than twiceand wore them for two years and more. Statistical analyses were performed to identify significant differences between the groups. Results: Among the failure group, failure to continuously wear the Ortho-K lenses was attributed to undercorrection (19 patients), corneal erosion (2 patients), and sleep disorders (1 patient). Initial spherical diopter and initial spherical equivalent diopter showed statistical diffence between the success group and failure group. Of these two factors, as the initial spherical equivalent diopter increased, the chance of failure to use Ortho-K lens increased. According to a logistic multiple regression analysis, the odds of failure of using Ortho-K lens increased by 1.59 when the initial spherical diopter increased by 1. If the absolute value of the initial spherical diopter was over 6.24, the chance of failure increased by 80%. Conclusions: The failure of continuously wearing Ortho-K lenses due to undercorrection was found to be the major cause of failure in the correction of childhood myopia. The initial spherical diopter and initial spherical equivalent diopter were significant factors influencing the undercorrection. From these results, we predict that the odds of failure of continuously wearing Ortho-K lenses increases along with increases in the initial spherical diopter. In conclusion, clinicians should be warned concerning the odds of failure due to low initial spherical diopter. J Korean Ophthalmol Soc 2015;56(3):317-322

To compare isolation of staphylococci from periorbital tissues and accessories of orthokeratology (ortho-k) lens and spectacle wearers and investigate prevalence of antiseptic-resistance (QAC) genes. To determine minimum inhibitory concentrations (MIC) of antiseptics and antibiotic susceptibility of isolates. Staphylococci were isolated from eyelids, eyelashes, and conjunctival sacs of 23 ortho-k lens wearers and 20 spectacle wearers. Samples were also collected from ortho-k lenses, lens cases, and spectacle frames. Isolations of Staphylococcus aureus were compared between ortho-k subjects and controls for all samples and for coagulase-negative staphylococci (CNS) from conjunctival sacs. QAC genes were amplified in 110 S. aureus and 59 CNS isolates and prevalence compared in isolates from ortho-k lens and spectacle wearers. Associations were assessed between presence of QAC genes and antibiotic and antiseptic susceptibility. Although isolation of S. aureus did not differ significantly in periorbital samples from ortho-k and control subjects, QAC genes were significantly more common in both S. aureus and CNS from ortho-k subjects (odds ratio 4.4 and 10.74, respectively). Overall, qacA/B was the predominant gene detected, being present in 26.5% CNS and 11% S. aureus. smr and qacH were present in 12% of CNS, but were less common in S. aureus. QAC gene-positive isolates had higher MICs to benzalkonium chloride and chlorhexidine digluconate. Our results suggest that long-term use of multipurpose solutions containing quaternary ammonium compounds may select for carriage of organisms harboring QAC genes. As these genes are associated with antibiotic resistance, their increased prevalence in isolates from contact lens wearers is a concern.

Comparison of the efficacy of orthokeratology and highly aspherical lenslets in slowing myopia progression.

Lens decentration is common and unavoidable to some extent during ortho-k treatment. By using a simplified method, we are able to predict the magnitude and direction of ortho-k lens decentration, which provides useful insights in screening for ideal ortho-k candidates and to make a quick decision when decentration happens. The aim of this study was to investigate the influence of corneal elevation asymmetry on ortho-k lens decentration. Thirty-six eyes of 36 subjects were fitted with four-curve reverse geometry ortho-k contact lenses. Corneal topography was collected before and 1 month after ortho-k lens wear. The difference in corneal elevation at the 8-mm chord of the respective two principal meridians of corneal astigmatism was calculated. Vector analyses were performed on these differences to calculate the magnitude and direction of a vector (corneal asymmetry vector). The relationship between the angle and magnitude of corneal asymmetry vector and lens decentration was analyzed. Baseline refractive sphere and cylinder for the 36 tested eyes were -2.84 ± 1.04 diopters (D) (range, -4.75 to -1.00 D) and -0.21 ± 0.28 D (range, -1.00 to 0 D), respectively. The mean magnitude of lens decentration was 0.72 ± 0.26 mm (0 to 1.34 mm). For overall displacement, inferotemporal decentration was the most common as observed in 24 eyes (67%). The mean angle of the corneal asymmetry vector (202 ± 39 degrees) was significantly correlated to the mean angle of lens decentration (200 ± 39 degrees) (r = 0.76, P < .001). The magnitude of corneal asymmetry vector significantly contributed to the magnitude of lens decentration (standardized β = 0.448, P = .002) whereas the other tested variables did not affect lens decentration (all P > .05). Lens decentration is a common phenomenon in ortho-k that mostly happens toward the inferotemporal quadrant of the cornea. The magnitude and direction of lens decentration are predetermined by paracentral corneal asymmetry.

BackgroundMany efforts have been invested in slowing progression of myopia. Among the methods, atropine administration and orthokeratology (OK) are most widely used. This study analyzed the efficacy of atropine and OK lens in controlling myopia progression and elongation of axial length.MethodsThis retrospective study included 105 patients (210 eyes) who wore OK lenses and 105 patients (210 eyes) who applied 0.125% atropine every night during the 3 following period. Student t-test, linear regression analysis, repeated measure ANOVA, and Pearson’s correlation coefficient were used for statistical analysis.ResultsThe change in axial length per year was 0.28 ± 0.08 mm, 0.30 ± 0.09 mm, and 0.27 ± 0.10 mm in the OK lens group, and 0.38 ± 0.09 mm, 0.37 ± 0.12 mm, and 0.36 ± 0.08 mm in the atropine group for years 1, 2, and 3, respectively. Linear regression analysis revealed an increase in myopia of 0.28 D and 0.34 D per year, and an increase in axial length of 0.28 mm and 0.37 mm per year in the OK lens and atropine groups, respectively. Repeated measure ANOVA showed significant differences in myopia (p = 0.001) and axial length (p < 0.001) between the atropine and OK lens groups; in astigmatism, there was no significant difference in these parameters (p = 0.320). Comparison of increases in axial length in relation to baseline myopia showed significant correlations both in the OK lens group (Pearson’s correlation coefficient, r = 0.259; p < 0.001) and atropine group (r = 0.169; p = 0.014). High myopia patients benefited more from both OK lenses and atropine than did low myopia patients. The correlation of baseline myopia and myopia progression was stronger in the OK lens group then in the atropine group.ConclusionsOK lens is a useful method for controlling myopia progression even in high myopia patients.

Background: Orthokeratology (Ortho-K) effectively slows axial elongation in myopic eyes, but its long-term effects on peripheral refraction (PR) and its relationship with myopia progression remains unclear. Aim: This study aimed to determine the changes in PR and myopia progression over 36 months of Ortho-K wear in children. Setting: This is a prospective cohort study. Methods: Twenty-nine myopic children aged 8–9 years old were enrolled in this study. Ortho-K lenses were prescribed, and analyses were conducted at baseline, 12, and 36 months (M). Assessments included axial length (AL) and cycloplegic refraction at central and peripheral (30°N, 20°N, 10°N, 10°T, 20°T, and 30°T). Intraocular pressure (IOP), corneal thickness and endothelial morphology were monitored throughout the study. Data were analysed using repeated-measures ANOVA or the Friedman test, with Bonferroni correction; p &lt; 0.05 was considered significant. Results: Relative peripheral refraction (RPR) shifted from baseline hyperopic to myopic defocus at 12M at 30°N, 20°N, 20°T, and 30°T (p &lt; 0.01). A further significant myopic shift was observed at 20°N after 12M, but no correlation with AL growth. Axial length decreased significantly in the first year (−0.16 ± 0.04 mm, p = 0.003), then elongated slowly thereafter (0.24 ± 0.08 mm in the next 24M, p = 0.02). Best corrected visual acuity remained stable, and no significant changes in ocular health parameters or complications were observed. Conclusion: Wearing Ortho-K lenses for 36 months slowed down axial elongation and sustained peripheral myopic defocus without compromising ocular health. Regular IOP and corneal health monitoring are recommended to ensure stable ocular physiology during long-term Ortho-K wear. Contribution: This study provides evidence on the effectiveness and ocular physiological responses of long-term wearing of Ortho-K lenses in children.

We investigated changes in choroidal vascularity and choriocapillaris blood perfusion during orthokeratology (Ortho-K) lens wear. Sixty-two children with low to moderate myopia were enrolled. The Ortho-K group (n = 42) continuously wore Ortho-K lenses for 3 months, and the controls (n = 20) wore single-vision distance spectacles. All of the patients were instructed to return for follow-up visits after 1 day, 1 week and 1 month and 3 months of treatment. The subfoveal choroidal thickness (SFChT), choroidal vascularity [including the total choroidal area, luminal area, stromal area, and choroidal vascularity index (CVI)] and percentage of choriocapillaris flow voids (FV%) were determined with a Cirrus HD-OCT instrument. Additionally, ocular parameters were measured. In the Ortho-K group, the SFChT significantly increased by 12.61 ± 5.90 μm, the CVI was significantly increased by 2.99 ± 2.07% and 3.01 ± 2.32% on the horizontal and vertical scans respectively, and the FV% was significantly decreased by 0.89 ± 0.34% from baseline at the 1-week visit (all p < 0.001). The choroidal parameters remained unchanged at the 1-month and 3-month follow-ups with respect to the 1-week follow-up. In the control group, the choroidal parameters did not change significantly at 1 month (all p > 0.05). At the 3-month visit, the changes in the axial length (AL) and vitreous chamber depth (VCD) were significantly greater in the control group than in the Ortho-K group (0.14 ± 0.23 and 0.03 ± 0.05 mm in AL, 0.15 ± 0.23 and 0.06 ± 0.03 mm in VCD respectively). Our longitudinal study showed several choroidal parameter changes in the early stage in Ortho-K lens wearers with low to moderate myopia, and these changes persisted over 3 months. We speculate that Ortho-K lenses regulate choroidal thickness and blood perfusion, affecting myopia development.

Myopia is increasing worldwide. Although the exact etiology of myopia is unknown, outdoor activity is one of the most important environmental factors for myopia control. We previously reported that violet light (VL, 360–400 nm wavelength), which is abundant in the outdoor environment, suppressed myopia progression for individuals under 20 years of age. However, whether VL is also effective for adult high myopia, which can be sight-threatening, has remained unknown. To investigate the influence of VL for adult myopia, we retrospectively compared the myopic progression and the axial length elongation over five years in adult high myopic patients over 25 years of age after two types (non-VL transmitting and VL transmitting) of phakic intraocular lens (pIOL) implantation. We found that high myopic patients with the non-VL transmitting pIOLs implanted are almost two times more myopic in the change of refraction and four times longer in the change of axial length, compared to those implanted with the VL transmitting pIOLs. This result indicated that the VL transmitting pIOL suppressed myopia progression and axial length elongation compared with the non-VL transmitting one. In conclusion, our study showed the VL possibly has an anti-myopia effect for human adults with high myopia.

Previous studies have linked high myopia (HM) to brain activity, and the difference between HM and low myopia (LM) can be assessed. To study the differences in functional networks of brain activity between HM and LM by the voxel-level degree centrality (DC) method. Twenty-eight patients with HM (10 men, 18 women), 18 patients with LM (4 men, 14 women), and 59 healthy controls (27 men, 32 women) were enrolled in this study. The voxel-level DC method was used to assess spontaneous brain activity. Correlation analysis was used to explore the change of average DC value in different brain regions, in order to analyze differences in brain activity between HM and LM. DC values of the right cerebellum anterior lobe/brainstem, right parahippocampal gyrus, and left caudate in HM patients were significantly higher than those in LM patients (P < 0.05). In contrast, DC values of the left medial frontal gyrus, right inferior frontal gyrus, left middle frontal gyrus, and left inferior parietal lobule were significantly lower in patients with HM (P < 0.05). However, there was no correlation between behavior and average DC values in different brain regions (P < 0.05). Different changes in brain regions between HM and LM may indicate differences in neural mechanisms between HM and LM. DC values could be useful as biomarkers for differences in brain activity between patients with HM and LM. This study provides a new method to assess differences in functional networks of brain activity between patients with HM and LM.

Myopia, also known as nearsightedness, is the most common vision disorder among children and young adults. In the last several decades, the prevalence of myopia has surged in East Asia. In some industrialized regions it has already reached an epidemic level (1,2). A smaller increase in the prevalence has also been observed in Western countries (2,3). The cost of visual aids or corrections put a great financial burden on individuals, families and the health care system. Myopia is not just an optical inconvenience. Early onset myopia is often accompanied with fast progression and very likely it will end up with high myopia (higher than 6.00 D myopia). High myopia poses a higher risk for developing glaucoma, retinal detachments and other vision threatening conditions. As our understanding of myopia was and is still poor, the research and development of an effective and safe tool in controlling myopia has been moving forward slowly. The current options for slowing down myopia progression include applying pharmaceutical agents such as atropine, wearing corrections with special optical design including bifocal spectacles, dual-focal contact lenses, and orthokeratology (ortho-K) (4). The most effective treatment up-to-date is 1% atropine, with well-established clinically relevant efficacy. However, the side-effect of long-term use and rebound effect after discontinuation of atropine were major concerns. Recently published results from a study conducted in Singapore clearly showed that atropine at a much lower dosage 0.01% could slow down myopia progression in children though its treatment size was smaller compared to the higher dosage levels: 1.0%, 0.5% and 0.1% (5). In addition, their results indicated that the group with 0.01% atropine had little rebound after cessation of the treatment while the other groups progressed much faster than the control group. More investigations on this promising strategy are still ongoing. Another promising option is ortho-K contact lenses. The benefit of wearing ortho-K in retarding axial elongation has been confirmed by randomized clinical trials (RCTs) (6). Prescribing contact lenses in very young children is still non-conventional due to hygiene and safety concerns. Other optical correction methods include multifocal and bifocal spectacles. Multifocal/bifocal spectacle provides minimal myopia control effect: statistically significant but without clinical significance (4). Finally, none of these intervention methods had been studied for a long period of time (>5 years) and thus their long-term effect is unknown. Unlike studies on retarding myopia progression, publications on myopia prevention methods are rarely seen in literature.

ObjectiveTo investigate the correlation between first-year axial elongation and 10-year (adulthood) axial length (AL) outcomes in children wearing orthokeratology (Ortho-K) lenses, and to develop predictive models for long-term myopia control.MethodsData from 101 children who wore Ortho-K lenses for 10 years (2011–2025 cohort) were analyzed. Feature selection was performed using Single- and multi-factor logistic regression, LASSO, and the Boruta algorithm. Outcomes included AL > 26 mm after 10 years and rapid late-stage progression (annual increase >0.1 mm between years 9 and 10). Predictive models were visualized via dynamic nomograms.ResultsFirst-year AL change (Change AL), baseline AL, and flat eccentricity (Flat E) were significant predictors for 10-year AL > 26 mm. The optimized model achieved an AUC of 0.952. A model only combining Chang AL predicted progression in years 9–10 with an AUC of 0.995. The optimal Chang AL cutoff for predicting stable 10-year progression was 0.28 mm overall (AUC = 0.978). Age-specific cutoffs were 0.28 mm for 8–9 years and 0.29 mm for 10–13 years.ConclusionThe first-year treatment response is an important indicator of adult-stage and long-term myopia progression in Ortho-K wearers. Monitoring the 0.28 mm first-year elongation threshold enables early identification of children at risk of poor long-term control.

To determine the repeatability of corneal hysteresis (CH) and corneal resistance factor (CRF) measurements in children wearing spectacles and children under orthokeratology (ortho-k) therapy using the Ocular Response Analyzer (ORA). CH and CRF were measured twice at a 10-min interval using ORA on the same day in both eyes of 25 children (mean age = 10.6 ± 1.2 years) wearing spectacles and 34 children (mean age = 10.9 ± 1.0 years) wearing ortho-k lenses. Four measurements were obtained from each eye in each set of measurements. Only data from the right eyes were analyzed. No significant between-measurement differences in CH and CRF were found in either group of subjects (paired t-tests, p > 0.05) and no correlations were found between the mean differences and their means (Pearson's correlations, -0.09 < r < 0.21, 0.24 < p < 0.85). The 95% limits of agreement (LA) were -1.87 mmHg to +2.59 mmHg and -1.53 mmHg to +1.41 mmHg for CH and -1.86 mmHg to +2.22 mmHg and -1.45 mmHg to +1.57 mmHg for CRF in the spectacle and ortho-k groups, respectively. A significant between-group difference in CRF was found (unpaired t-tests, p = 0.02). Repeatability of CH and CRF measurements using the ORA is within ± 2 mmHg in children wearing spectacles or ortho-k lenses. We suggest that the ORA can be used to monitor long-term corneal biomechanical changes during ortho-k treatment.

A trend that myopia is becoming gradually more common is shown in studies worldwide. Highest frequencies have been found in East Asian urban populations (96.5%) but also a study in Europe shows that nearly half of the 25-29 year olds has myopia. With the increase in prevalence, high myopia, i.e. a spherical equivalent of -6 or more and an axial length of 26 mm or more is also on the rise. High myopia particularly carries a significant risk of ocular pathology related to the long axial length. This highlights the need for myopia management in children with progressive myopia, in particular progression to high myopia. During the last decade, many intervention studies for myopia progression have emerged. Although lifestyle adjustments are effective, pharmacological and optical interventions have shown the highest efficacy on reduction of eye growth. High concentration atropine (0.5%-1.0%) shows the most reduction in axial length progression, but has drawbacks of light sensitivity and loss of accommodation. Nevertheless, when these side effects are mitigated by multifocal photochromatic glasses, the long-term adherence to high dose atropine is high. Lower concentrations of atropine are less effective, but have less side effects. Studies on optical interventions have reported reduction of progression for Ortho-K and multifocal contact lenses, but are in need for replication in larger studies with longer duration. The field of myopia management is rapidly evolving, and a position on the best approach for daily clinics is desirable. Over the last 10 years, our team of clinical researchers has developed a strategy which involves decision-making based on age, axial length, position on the axial length growth chart, progression rate, risk of high myopia, risk profile based on lifestyle and familial risk, side effects, and individual preference. This personalised approach ensures the most optimal long-term myopia control, and helps fight against visual impairment and blindness in the next generations of elderly.