Orthokeratology Contact Research Articles

The Impact of Antibiotic Usage Guidelines, Developed and Disseminated through Internet, on the Knowledge, Attitude and Prescribing Habits of Orthokeratology Contact Lens Practitioners in China.

It has been previously reported that the improper prescribing of antibiotic eye drops is common among orthokeratology (ortho-k) practitioners. Guidelines have since been developed and disseminated to improve their understanding and implementation of antibiotic prescriptions. This study aimed to investigate the influence of these guidelines on the knowledge, attitude, and prescribing habits of ortho-k practitioners by means of a questionnaire, which was administered nationwide via an official online account to eye care practitioners (ECPs) involved in ortho-k lens fitting, 548 of whom completed the survey. Differences in characteristics before and after the dissemination of the guidelines and between the groups were explored using χ2 tests. The relationship between prescribing habits and demographics was analyzed using stepwise logistic regression models. The implementation of the guidelines significantly improved the overall prescribing habits of ECPs (p < 0.001), especially for prophylactic antibiotic use before and after ortho-k lens wear (p < 0.001). Most ECPs who prescribed antibiotics properly displayed significantly better knowledge of correct antibiotic use, which in turn affected the compliance in their ortho-k patients (p < 0.001). The ECPs’ occupations (professionals other than ophthalmologists and optometrists, including nurses and opticians), clinical setting (distributor fitting centers), and age (younger than 25 years) were risk factors for the misuse of antibiotics. Although the implementation of the antibiotic guidelines significantly improved overall prescribing habits, some practitioners’ prescribing behavior still needs improvement. A limitation of this study was that all questions were mandatory, requiring ECPs to recall information, and therefore was subjected to selection and recall bias.

A new approach for quantifying epithelial and stromal thickness changes after orthokeratology contact lens wear.

The aim of the study was to develop an automatic segmentation approach to optical coherence tomography (OCT) images and to investigate the changes in epithelial and stromal thickness profile and radius of curvature after the use of orthokeratology (Ortho-K) contact lenses. A total of 45 right eyes from 52 participants were monitored before, and after one month of, uninterrupted overnight Ortho-K lens wear. The tomography of their right eyes was obtained using optical OCT and rotating Scheimpflug imaging (OCULUS Pentacam). A custom-built MATLAB code for automatic segmentation of corneal OCT images was created and used to assess changes in epithelial thickness, stromal thickness, corneal and stromal profiles and radii of curvature before, and after one month of, uninterrupted overnight wear of Ortho-K lenses. In the central area (0–2 mm diameter), the epithelium thinned by 12.8 ± 6.0 µm (23.8% on average, p < 0.01) after one month of Ortho-K lens wear. In the paracentral area (2–5 mm diameter), the epithelium thinned nasally and temporally (by 2.4 ± 5.9 µm, 4.5% on average, p = 0.031). The stroma thickness increased in the central area (by 4.8 ± 16.1 µm, p = 0.005). The radius of curvature of the central corneal anterior surface increased by 0.24 ± 0.26 mm (3.1%, p < 0.01) along the horizontal meridian and by 0.34 ± 0.18 mm (4.2%, p < 0.01) along the vertical meridian. There were no significant changes in the anterior and posterior stromal radius of curvature. This study introduced a new method to automatically detect the anterior corneal surface, the epithelial posterior surface and the posterior corneal surface in OCT scans. Overnight wear of Ortho-K lenses caused thinning of the central corneal epithelium. The anterior corneal surface became flattered while the anterior and posterior surfaces of the stroma did not undergo significant changes. The results are consistent with the changes reported in previous studies. The reduction in myopic refractive error caused by Ortho-K lens wear was mainly due to changes in corneal epithelium thickness profile.

The relationship between myopia progression and axial elongation in children wearing orthokeratology contact lenses

PurposeTo investigate the relationship between myopia progression and axial length (AL) elongation in orthokeratology (ortho-k) patients. MethodsThis study investigated 184 patients (baseline age 9.0 ± 1.6 years), who underwent overnight ortho-k treatment for 12 to 72 months, and stopped lens wear for 1 to 2 months. Refractive sphere and cylinder after cycloplegia, corneal curvatures along both meridians, and AL were compared before the commencement and after discontinuation of ortho-k treatment. The effects of AL change, baseline AL, corneal curvature change, baseline age, and duration of ortho-k treatment on the change in spherical equivalent refractive error (SER) were analysed. ResultsMyopia significantly progressed and AL increased following 32.8 ± 13.0 months of ortho-k lens wear and 1 to 2 months washout period, as compared to baseline (all P < 0.001). Corneal curvature along the flat meridian (FK) became significantly flatter (P < 0.001) and corneal curvature along the steep meridian (SK) became steeper (P = 0.036). In the first stepwise multiple linear regression model (R2 = 0.696), the change in SER over time (ΔSER) is significantly correlated to the change in AL (ΔAL, P < 0.001), baseline AL (P < 0.001), baseline age (P = 0.028), change in SK (P = 0.002), and the duration of ortho-k lens treatment before discontinuation (P = 0.010). In a more simplified model (R2 = 0.628), the regression equation using ΔAL to predict ΔSER is: ΔSER = -0.094–1.608*ΔAL. ConclusionsThe change in SER was significantly correlated to the change in AL, change in SK, baseline AL, baseline age, and the duration of treatment among children undergoing ortho-k therapy. The ratio of axial elongation to myopia progression was approximately 1:1.6 between the ages of 6 to 14 years. A simplified equation was derived for clinical use to estimate myopia progression from repeated AL measurement in ortho-k patients.

A novel quantitative evaluation of deposits adhered to worn orthokeratology contact lenses.

Total deposition and deposition along the reverse curve of heavily deposited worn orthokeratology (OK) lenses were quantitatively evaluated using two novel imaging methods. In addition, the cleaning efficacies of a contact lens cleaning solution for daily use and an intensive cleaner and protein remover solution were evaluated using the same two methods. Experimental study. Twenty-six worn reverse-geometry OK lenses (MY Emerald, Technopia) were photographed for use in three experiments: (1) total deposition was assessed before and after cleaning with two cleaning solutions; (2) in addition to assessing total lens deposition, the feasibility of measuring the thickness of lens deposits along the reverse curve was assessed; and (3) after confirming it was possible to assess the thickness of lens deposits, the thickness of deposits was assessed before and after cleaning with a daily contact lens cleaning solution (O2 Care®, Menicon Co., Ltd.) and an intensive cleaner and protein remover (Progent®, Menicon Co., Ltd.). Total lens deposition was assessed as the total volume of cloudiness over the lens surface in terms of volume per unit pixel. Cross-sectional images were taken from worn OK lenses to assess the thickness of lens deposits on the reverse curve as the area of deposits/horizontal length. Significant differences in total deposition were found between the three cleaning conditions for the twenty worn OK lenses (mean total deposition ± SD for pre-cleaning = 0.209 ± 0.076; post-daily cleaning = 0.124 ± 0.078; and post-intensive cleaning = 0.045 ± 0.046) (p < 0.001). Mean total deposition and thickness of the deposits along the reverse curve for the three lenses from the second experiment were 0.310 and 6.0mm, respectively. The mean thicknesses of lens deposits found in the third experiment under the 3 conditions were as follows: pre-cleaning = 3.4µm; post-daily cleaning = 2.3µm; and post-intensive cleaning = 0.0µm. The two novel imaging methods used in this study detected significant amounts of deposits attached to worn OK lenses and were sensitive enough to detect a reduction in deposition following the use of the two cleaning solutions tested. Furthermore, these methods could visualize and quantify the thickness of lens deposits along the reverse curve.

Integrating Clinical Data and Tear Proteomics to Assess Efficacy, Ocular Surface Status, and Biomarker Response After Orthokeratology Lens Wear.

PurposeThis study evaluated the efficacy and ocular surface status of Breath-O Correct, novel orthokeratology (OK) lenses, worn overnight for 3 months. Lens-induced changes in the tear proteome were evaluated.MethodsThirty-one subjects, aged 19 to 26 years with refractive error from −1.00 to −5.00 D, were randomly assigned 1:1 to the treatment or control group. Refraction, visual acuity, corneal integrity, biomechanics and endothelial health, ocular surface changes, and subjective symptoms were assessed at the baseline, one-month, and three-month visits. The tear proteome was characterized over time using sequential window acquisition of all theoretical ion spectra mass spectrometry.ResultsLenses improved uncorrected visual acuity and reduced spherical powers with similar efficacy to other OK lenses. Significant reductions (P < 0.05) in corneal hysteresis (11.12 ± 1.12 to 10.38 ± 1.36 mm Hg) and corneal resistance factor (11.06 ± 1.32 to 9.90 ± 1.45 mm Hg) were observed in the treatment group after one month of lens wear, whereas other assessed factors remained unchanged. Thirteen and eight differentially expressed proteins were found after one month and three months of lens wear, respectively. Two proteins (proline-rich protein 27 and immunoglobulin V regions) were differentially expressed at both visits.ConclusionsOver a three-month period, Breath-O Correct lenses were overall safe, well tolerated, efficacious in refractive power reduction, and comparable with other OK lenses. Furthermore, their use caused only minor noninflammatory protein expression changes in the tear proteome.Translational RelevanceThis study investigated the safety of orthokeratology contact lenses on the ocular surface in molecular aspects and standard clinical parameters.

Epidemiology of Myopia in Children of the Russian Federation and Analysis of Its Control Methods

The increasing prevalence of myopia is observed all over the world, and Russia is no exception. In this regard, obtaining new data on its epidemiology among children and assessing methods of its control in real clinical practice are highly topical matters.Purpose. The purpose of this work was to assess the current issues of the epidemiology and treatment of progressive myopia in children in various regions of the Russian Federation.Materials and methods. We conducted a prospective multicenter epidemiological observational questionnaire study. This study involved 106 doctors from 53 regions of Russia and 2931 parents of myopic children.Results. 50% of the surveyed doctors noted that the manifestation of myopia is diagnosed in children aged 10–12 years, while 43% noted the same in children aged 7–9 years. According to 74.5% of doctors, the degree of the newly diagnosed myopia ranges from –1.25 to –3.00 diopters, 25.5% of doctors reported that it is below –1.0 diopters. The majority of doctors (73.6%) assess accommodation in myopic children, considering it one of the progression factors. 52.9% of ophthalmologists prescribe optical correction in cases when monocular distance visual acuity amounts to 0.6 (decimal scale) or lower values, while 29.2%, 16% and 1.9% of the surveyed ophthalmologists prescribe optical correction in cases when monocular distance visual acuity amounts to 0.7, 0.8 and 0.9 respectively.The following optical methods for juvenile myopia control are recommended by the doctors: orthokeratology contact lenses (53.8%), spectacles for full correction (51.9%), peripheral defocus-inducing (bifocal) soft contact lenses (18.9%), while 4.7% of the surveyed doctors utilized other methods of myopia control, which were not indicated in the questionnaire.Conclusion. In most cases, manifestation of myopia is diagnosed in children aged 7–12 years. Its degree ranges from –1.25 to –3.0 diopters, which indicates its late diagnosis; optical correction is prescribed mainly in cases when monocular distance visual acuity is 0.6 or lower; most ophthalmologists assess accommodation in myopic children, considering it a progression factor. As methods of myopia control, doctors utilize optical correction, device-assisted therapy and pharmacological treatment of accommodative disorders, while parents prefer methods that require minimum time expenditures.

Our Experience of Using Soft Bifocal Contact Lenses in Children with Progressive Myopia

Introduction. According to the studies, one out of three myopic patients with refraction greater than –6.00 D and an axial length greater than 26 mm is at high risk of facing low vision and loss of sight in the future. According to the results of medical examinations and screenings in carried out in Ivanovo, the prevalence of myopia in primary school children has increased three times during the past twenty years. Myopic children under 7 years old are six times more likely to have myopia progressed to higher degrees than children in which myopia onset took place later (at the age of 11–12 years). Optical interventions for myopia control such as orthokeratology and soft bifocal contact lenses have a strong body of evidence and are well accepted by ophthalmologists.Purpose. The purpose of the present study was to investigate the effect of soft bifocal contact lenses on refraction, accommodation and axial length in children with progressive myopia.Materials and methods. We observed 30 children aged 8–15 years with myopia progression rate of 0.82 D/year and accommodative weakness and instability. We prescribed OKVision PrimaBio Bi-focal design soft bifocal contact lenses (OKVision, Russia) that feature +4.00 D addition power on periphery. The effectiveness was estimated by monitoring refraction, accommodation and axial length every three months within a year.Results. After 12 months of wearing soft bifocal contact lenses, the annual myopia progression rate decreased 4.3 times on average. We were able to stabilize myopia in 50% of the children during the period of monitoring. The use of this intervention had a strong effect on accommodation resulting in an increase of its amplitude and reserve.Conclusion. The use of soft bifocal contact lenses has been proven to have a strong inhibitory effect on myopia progression rate. Myopia stabilization manifested itself as the absence of increase in myopic refraction and axial length as well as normalization of accommodative function.

Role of Short Term Open Eye OrthoK Lens Wear in Inducing Myopia Control Changes in Eyes With Moderate Myopia

Purpose: To assess peripheral refraction, corneal, and visual acuity changes after open eye use of orthokeratology (OrthoK) contact lenses. Methodology: OrthoK contact lenses were worn on separate occasions for half an hour and 2 hours in open eye condition. The peripheral refraction (PR) changes were assessed monocularly up to 30° nasally and temporally in the horizontal visual field using the open field autorefractometer. Average corneal power (ACP), central corneal thickness (CCT), and visual acuity (VA) was recorded using corneal topographer, specular microscope, and LogMAR chart respectively. Results: Mean baseline PR at 25° and beyond both nasally and temporally was -0.54 ± 1.68D (mean ± SD) which increased to mean -1.29 ± 1.43D (p < 0.01) post half an hour of lens wear and further increased to mean -1.62 ± 1.53D (p < 0.01) after 2 hours lens wear. The mean baseline ACP was 43.45 ± 1.34D that reduced to mean 43.11 ± 1.37D (p < 0.01) after half an hour of lens wear and a further reduction to mean 42.73 ± 1.34D (p < 0.01) 2 hours post lens wear. Mean CCT changes after half an hour lens wear were not significant but it reduced by mean 14.92 ± 4.68 µm (p < 0.01) 2 hours post lens wear as compared to baseline. The unaided VA improved from mean 0.85 + 0.37 log at baseline to mean 0.49 + 0.35 log (p < 0.01) after half an hour of lens wear and mean 0.39 + 0.35 log (p < 0.01) after 2 hours of OrthoK lens wear. Conclusion: Rapid corneal and peripheral refraction shifts are seen after half an hour of open-eye wear of the OrthoK lens with a gradual rise in impact for 2 hours of lens wear.

Role of Short Term Open Eye Orthok Lens Wear in Inducing Myopia Control Changes in Eyes with Moderate Myopia

Purpose: To assess peripheral refraction, corneal, and visual acuity changes after open eye use of orthokeratology (OrthoK) contact lenses. Methodology: OrthoK contact lenses were worn on separate occasions for half an hour and 2 hours in open eye condition. The peripheral refraction (PR) changes were assessed monocularly up to 30° nasally and temporally in the horizontal visual field using the open field autorefractometer. Average corneal power (ACP), central corneal thickness (CCT), and visual acuity (VA) was recorded using corneal topographer, specular microscope, and LogMAR chart respectively. Results: Mean baseline PR at 25° and beyond both nasally and temporally was -0.54 ± 1.68D (mean ± SD) which increased to mean -1.29 ± 1.43D (p &lt; 0.01) post half an hour of lens wear and further increased to mean -1.62 ± 1.53D (p &lt; 0.01) after 2 hours lens wear. The mean baseline ACP was 43.45 ± 1.34D that reduced to mean 43.11 ± 1.37D (p &lt; 0.01) after half an hour of lens wear and a further reduction to mean 42.73 ± 1.34D (p &lt; 0.01) 2 hours post lens wear. Mean CCT changes after half an hour lens wear were not significant but it reduced by mean 14.92 ± 4.68 µm (p &lt; 0.01) 2 hours post lens wear as compared to baseline. The unaided VA improved from mean 0.85 + 0.37 log at baseline to mean 0.49 + 0.35 log (p &lt; 0.01) after half an hour of lens wear and mean 0.39 + 0.35 log (p &lt; 0.01) after 2 hours of OrthoK lens wear. Conclusion: Rapid corneal and peripheral refraction shifts are seen after half an hour of open-eye wear of the OrthoK lens with a gradual rise in impact for 2 hours of lens wear.

Lenses and Spectacles to Prevent Myopia Worsening in Children

&#x0D; A total of 5 relevant systematic reviews and 7 randomized controlled trials (RCTs) were identified.&#x0D; Myopia progression and axial length elongation was less with omafilcon A (MiSight) contact lenses compared to single-vision lenses (1 RCT; statistical significance of difference was not reported).&#x0D; Myopia progression and axial length elongation was less with defocus incorporated multiple segments spectacle lenses compared to single-vision spectacle lenses (1 RCT; the between-group difference was statistically significant).&#x0D; Myopia progression was less with orthokeratology contact lenses compared to single-vision contact lenses or single-vision lenses (2 systematic reviews and 2 RCTs; between-group difference was statistically significant or statistical significance was not reported) and axial length elongation was less (5 systematic reviews and 2 RCTs; between-group difference was statistically significant or statistical significance was not reported).&#x0D; Myopia progression and axial length elongation was less with multifocal lenses compared with single-vision contact lenses (1 systematic review and 2 RCTs; between-group difference was statistically significant).&#x0D; Findings need to be interpreted in the light of limitations, such as limited quantity and quality of the included primary studies, limited information regarding adverse events, and lack of long-term data.&#x0D; No economic evaluations reporting on the cost-effectiveness of these interventions were identified.&#x0D;

Efficacy of software-based fitting in orthokeratology

Purpose: Some markets fit ortho-keratology (OK) using trial contact lenses (CLs). This can make the procedure complicated; more experience is needed, it can be time consuming and there is a risk of cross infection with trial lenses. In western markets, most OK CLs are fitted empirically with digital software, calculating the unique CLs based on topography and subjective refraction. This study was to analyse the overall success of digital OK fitting and the quantity of lens exchanges needed to reach success.

Tear Lipid Layer Thickness in Children after Short-Term Overnight Orthokeratology Contact Lens Wear

Meibomian gland lipid secretion is important to the stability of the tear film and ocular surface comfort. Changes in the tear film’s lipid layer thickness (LLT) after orthokeratology treatment may reflect underlying changes to the meibomian gland function. The purpose of this study was to investigate the features of the tear lipid layer in normal children and the effects of short-term orthokeratology treatment. Altogether, 163 myopic children (age: 10.7 ± 1.9 years, 8–15 years; 71 males) with no contact lens use history were enrolled in this study, of whom 56 were successfully fitted with orthokeratology lenses and completed the 1-month study. The tear film’s LLT (average, maximum, and minimum) and blinking pattern were measured by a LipiView® interferometer in 163 participants at baseline and in 56 orthokeratology participants at 1 week and 1 month after overnight lens wear. Results show that LLT (average) was 58.09 ± 21.66 nm in Chinese normal children. LLT was significantly correlated with rate of partial blinks at every follow-up (all p &lt; 0.05 ). Compared to baseline, the LLT (average and minimum) and partial blinks (number and rate) at 1 week and 1 month after orthokeratology treatment both significantly increased, and the increase of LLT was correlated with elevation of rate of partial blinks. In conclusion, LLT was shown to be elevated after short-term overnight orthokeratology treatment and was related to change in rate of partial blinks. Further studies are needed to clarify the long-term effect and the underlying mechanism.

Manipulation of Front-Surface Profile of Scleral Contact Lenses to Alter Peripheral Refraction

The front optic zone diameter of scleral contact lenses was manipulated to mimic the central treatment zone induced by orthokeratology contact lens wear, to explore potential effects on the peripheral refraction profile. The purpose of this study was to investigate effects on the peripheral refraction profile of changing front optic zone diameters of scleral contact lenses. Twelve young adults were fitted with scleral contact lenses (diameter, 16.5 mm) with two front optic zone diameters (6 and 4 mm) on one eye only on 2 separate days. Both lenses were fabricated with front optic zone power of -3.00 D and plano power outside the optic zone to mimic the orthokeratology treatment effect. All lenses had the same spherical back-surface design with a toric lens periphery. Peripheral refraction was measured at 10° increments along horizontal (±35°) and vertical (±30°) meridians before lens insertion and after 10 minutes of lens wear. Mixed-model analysis and post hoc t tests with Bonferroni correction were performed. Compared with baseline, no significant change in relative spherical equivalent refraction M was observed with 6-mm optic zone lenses along the horizontal meridian. However, a significant difference in relative M profile was found with 4-mm optic zone lenses (P = .009). M became myopic at all locations in the nasal visual field (P < .05) except at 35°. In contrast, compared with baseline, no significant changes in relative M were found with either 6- or 4-mm optic zone lenses along the vertical meridian. The greater myopic shift in relative peripheral refraction with 4-mm compared with 6-mm front optic zone lenses suggests that a reduced treatment zone diameter in orthokeratology may induce more myopic peripheral refraction changes. This may guide us toward novel orthokeratology lens designs for more effective myopia control.

CONTROLLING MYOPIA PROGRESSION IN CHILDREN

Main aim of this article was a systematic review on causes and management of Myopia progression in children. Myopia is a general disorder, affecting just about one-third of the US popula­tion and over 90% of the population in some East Asian countries. Elevated amounts of myopia are connected with a bigger risk of sight-threatening troubles, such as retinal detachment, choroidal degeneration, cataracts and glaucoma. Slowing the progression of myopia could potentially advantage millions of children in the India. Few approaches used for myopia organize have proven to be useful. Treatment options such as undercorrection of myopia, gas permeable contact lenses, and bifocal or multifocal spectacles have all been proven to be inef­fective for myopia control, although one recent randomized clinical trial using executive top bifocal spectacles on children with progressive myopia has shown to decrease the progression to nearly half of the control subjects. The most effective methods are the use of orthokeratology contact lenses, soft bifocal contact lenses, and pharmaceutical agents such as atropine, timolol or pirenzepine.&#x0D; Keyword: Myopia progression, pharmaceutical agents, lenses, treatment.

Orthokeratology for myopia control in Covid-19 era

Philip Morgan, Lyndon Jones and Kate Gifford evaluate considerations on using orthokeratology contact lenses for myopia control during the Covid-19 pandemic

Use of orthokeratology contact lenses in the treatment of progressive myopia

Orthokeratology is a method of non-surgical correction of refraction, which is based on the principle of biomechanical changes in the curvature of the cornea under the influence of «reverse geometry». This method was developed more than 50 years ago, however, it became widely used only in the early 2000s. The basis of this method is the use of special orthokeratology lenses that patients wear during the night. Peculiarity of these lenses is the ability to change curvature of the cornea, resulting in a flattening of its central part and thickening of the paracentral and peripheral sections, which leads to the formation of positive spherical aberration of the optical system. Such changes in the cornea resulting from partial desquamation of keratocytes and changes in their shape during 7–8 hours of influence during the night, lead to the normalization of refraction, which persists for the next 24 hours. Most often this method of vision correction is used in children and adolescents, since it allows not only to optimize visual acuity for a certain period of time, but also to stop the progression of myopia. Another indication for the correction of vision using orthokeratology lenses includes active sports and situations that exclude the possibility of wearing glasses or soft contact lenses.

Is It Possible to Predict Progression of Childhood Myopia Using Short-Term Axial Change After Orthokeratology?

To investigate changes in axial length in children undergoing orthokeratology (OK) and evaluate short-term axial change in predicting post-OK myopia progression. In this retrospective study, the subjects included 70 myopic children aged 8 to 15 years wearing OK contact lenses for more than 3 years. Axial length changes at 0.5, 1, 2, and 3 years relative to the baseline were measured. Patients were evaluated for age, spherical equivalent refraction (SER), pupil size, and half-year axial change using repeated analysis of variance and multivariate linear regression analysis to predict half to 3 year-axial elongation (AE, seventh-36th month post-OK). The axial length grew significantly during the 3 years; the mean annual axial growth was 0.20±0.12 mm. The half-year axial change was 0.04±0.12 mm. The univariate linear analyses showed that half to 3-year AE was correlated with baseline age (r=-0.393, P<0.001) and half-year axial change (r=0.379, P=0.001), but not pupil diameter (P=0.692) or SER (P=0.673). In a multiple linear regression model, the half to 3-year AE was related with the baseline age (standardized β=-0.312, P=0.007) and half-year axial change (standardized β=0.293, P=0.01). The model was fair (adjusted R=0.21) and statistically significant (F=10.24, P<0.001). It is practical to predict long-term AE with half-year axial change for children with OK correction. Therefore, this may aid in fast and timely measures in children who are predicted to have rapid myopia progression.

Effect of orthokeratology on precision and agreement assessment of a new swept-source optical coherence tomography biometer

BackgroundTo evaluate the effect of orthokeratology on precision of measurements in children using a new swept-source optical coherence tomography (SS-OCT) optical biometer (OA-2000), and agreement between its measurements and those provided by the commonly used IOLMaster based on partial coherence interferometry (PCI).MethodsThis study recruited fifty-one eyes of 51 normal children (8–16 years). An operator took measurements with the two biometers. Then, a second operator took measurements with the SS-OCT biometer. After orthokeratology was performed for one month, the same operators repeated the same procedures. Axial length (AL), mean keratometry (Km) at 2.5 mm and 3.0 mm diameters (Km2.5 and Km3.0), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and corneal diameter (CD) were analyzed.ResultsWith the SS-OCT optical biometer, the test-retest repeatability of AL measurements was < 0.06 mm. For all parameters, the coefficients of variation were < 1.23% and the intraclass correlation coefficients were > 0.95. The 95% limits of agreement of difference between the two devices for CD parameter were up to 1.53 mm. After orthokeratology, the fluctuation ranges of difference for Km3.0 measurement was 1.11 times higher than before orthokeratology, while the absolute values of difference for AL, Km2.5, ACD and CD measurements were comparable.ConclusionsBefore and after orthokeratology, the SS-OCT biometer showed high repeatability and reproducibility for all measurements. Wearing orthokeratology contact lenses affected the agreement between SS-OCT and PCI biometers for Km3.0 measurements. The CD measurement showed poor agreement between the two devices.

Redistribution of the corneal epithelium after overnight wear of orthokeratology contact lenses for myopia reduction

BackgroundTo investigate changes in the corneal thickness profile in juvenile myopia after overnight wear of orthokeratology lenses (OK). MethodsA total of 53 juveniles (53 right eyes) successfully wore OK between January 2016 and July 2017 and they were reviewed one day, one week and one month after first wearing it. Epithelial and corneal data were obtained by optical coherence tomography (OCT). Changes in uncorrected visual acuity, refractive error, corneal refractive power, and epithelial and corneal thickness were analyzed before and after wear of OK. ResultsThe corneal epithelium was reshaped after 1 day of OK; the myopia degree was reduced, and uncorrected visual acuity reached 0 logMAR at 1 week. The central (2 mm) average epithelial thickness was 52.04 ± 2.35 μm, 49.25 ± 2.67 μm, 45.91 ± 2.80 μm, and 47.53 ± 3.44 μm before and after 1 day, 1 week, and 1 month of OK, respectively (t = 4.497, 9.741, and 7.340, respectively, P<0.001). The central epithelium was thinnest at 1 week, when the average thinning of 6.13 ± 1.67 μm accounted for approximately 11.78 % ± 3.21 % of the total epithelium thickness at baseline. The epithelial thickness of the reverse curve zone was 51.83 ± 2.49 μm, 57.62 ± 3.01 μm, 59.43 ± 3.19 μm, and 60.22 ± 2.75 μm before and after 1 day, 1 week, and 1 month of OK, respectively, showing a significant increase over time (t=-4.752, -6.208, and -6.848, respectively, P < 0.001). ConclusionIn the early stage of OK, the corneal epithelium was redistributed very quickly. The central epithelium became thin, while the epithelium of the reverse curve zone correspondingly thickened. Effectively reduced the refractive power of the cornea equivalent to the effect of adding a concave spectacle lens, which ensures uncorrected vision after removal of the lenses.

Treating Uncomfortable Contact Lens Wear With Orthokeratology.

Many contact lens (CL) users permanently discontinue wear because of ocular dryness and discomfort. This study aimed to determine whether refitting symptomatic soft CL wearers in to orthokeratology could improve ocular symptoms and signs. This was a prospective, 3-month, open-label study of symptomatic (Contact Lens Dry Eye Questionnaire [CLDEQ-8] ≥12) soft CL wearers who were between the ages of 18 and 45 years. All subjects were refit into orthokeratology CLs (Emerald, Euclid Systems). The following tests were completed: CL history, Standardized Patient Evaluation of Eye Dryness (SPEED) questionnaire, CLDEQ-8, CLDEQ-4, logarithm of the minimum angle of resolution visual acuity, pupil size, refractive error, slit-lamp biomicroscopy, noninvasive tear break-up time, tear meniscus height, phenol red thread, conjunctival staining, corneal aesthesiometry, and corneal topography. Twenty-nine of 40 qualifying subjects (age=24.43±4.62 years) completed the study. No significant differences were detected between completed and noncomplete subjects. Completed subjects had significantly better CLDEQ-8, CLDEQ-4, and SPEED scores at 3 months compared with baseline. Completed subjects had significantly better conjunctival staining scores and flatter keratometry values at 1 month compared with baseline. Although not all symptomatic soft CL wearers were able to be refit into orthokeratology, subjects who were wearing orthokeratology at 3 months had a significant and clinically meaningful improvement in ocular symptoms. Additional work is needed to determine the mechanism leading to improved comfort because few clinical signs were changed after switching to orthokeratology.