Orthokeratology Contact Lens Wear Research Articles

Epidemiology of myopia and the effect of orthokeratology on controlling the disease

Introduction and objective
 Myopia is a defect of vision, which makes it impossible to see remote objects clearly. The disease can also lead to serious ocular problems. Myopia affects about 30% of the world population and -according to the estimates- that percentage is about to increase up to 50% within the next 30 years. Orthokeratology is a relatively new method on non-surgical, reversible correction of myopia. Specially designed lenses, worn at night, affects the shape of the cornea, which results in proper vision during the day.
 Review methods
 The aim of the study was evaluation of effectiveness of wearing orthokeratology contact lenses based on a review of medical literature published on PubMed in the last 5 years.
 Abbreviated description of the state of knowledge
 Research results show that wearing orthokeratology lenses have beneficial effects. Reduction of axial length of the eyeball and curvature of the cornea were observed. Progression of myopia was five times slower in children study group and three times slower in adult study group compared to control groups. It was proved, that favourable health effects persist through the first eight years of treatment. Due to the fact, that cornea has a limited susceptibility, a decrease in efficiency occurs in the following years. Usually no undesirable side effects are reported, yet the possible side effects are mild and disappear after a short time.
 Summary
 According to the results of recent studies, we can assume that orthokeratology is a safe and effective method of inhibition of myopia progression. The method may be especially recommended to children, to people working in such conditions, that make wearing standard contact lenses impossible and to people not qualified for laser or surgical vision correction.

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.

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.

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.

Long-term Efficacy of Orthokeratology Contact Lens Wear in Controlling the Progression of Childhood Myopia

ABSTRACTPurpose: The primary outcome of this study is to compare the axial length growth of white European myopic children wearing orthokeratology contact lenses (OK) to a control group (CT) over a 7-year period.Methods: Subjects 6–12 years of age with myopia −0.75 to −4.00DS and astigmatism ≤1.00DC were prospectively allocated OK or distance single-vision spectacles (SV) correction. Measurements of axial length (Zeiss IOLMaster), corneal topography, and cycloplegic refraction were taken at 6-month intervals over a 2-year period. Subjects were invited to return to the clinic approximately 5 years later (i.e., 7 years after the beginning of the study) for assessment of their ocular refractive and biometric components. The CT consisted of 4 SV and 12 subjects who switched from SV to soft contact lens wear after the initial 2 years of SV lens wear. Changes in axial length relative to baseline over a 7-year period were compared between groups.Results: Fourteen and 16 subjects from the OK and CT groups, respectively, were examined 6.7 ± 0.5 years after the beginning of the study. Statistically significant changes in the axial length were found over time and between groups (both p < 0.001), but not for the time*group interaction (p = 0.125). The change in the axial length for the OK group was 22% (p = 0.328), 42% (p = 0.007), 40% (p = 0.020), 41% (p = 0.013), and 33% (p = 0.062) lower than the CT group following 6, 12, 18, 24, and 84 months of lens wear, respectively.Conclusion: A trend toward a reduction in the rate of axial elongation of the order of 33% was found in the OK group in comparison to the CT group following 7 years of lens wear.

Utility of orthokeratology contact lenses; efficacy of myopia correction and level of patient satisfaction in Iranian myopic/myope-astigmatic patients

PurposeTo investigate the medical profiles of patients referred to Iran Lens Clinic with myopic/myope-astigmatic refractive errors. MethodsMedical records of 182 patients (364 eyes) with myopic/myope-astigmatic refractive errors that underwent orthokeratology contact lens wear and fulfilled a 6-month period of follow-up were recruited. Efficacy and safety of these contact lenses in improving the visual acuity and correction of the refractive errors were investigated. Time needed to achieve final targeted visual acuity and association of various factors in this time course and level of acuity were investigated. Complications related to these lenses that were recorded in the medical profiles were studied. ResultsIn manifest refraction, the amount of spherical equivalent and myopia decreased significantly after orthokeratology contact lens wear (P < 0.001). A significant negative association was found between amount of mean baseline spherical equivalent and final achieved mean uncorrected visual acuity (P < 0.001). None of the parameters of age, gender, and keratometric findings influenced the outcomes significantly (P > 0.1). ConclusionPatients with myopic refractive error lower than −5.0 Diopters achieved higher final visual acuities rather than patients with higher amounts of myopic refractive errors.

Higher spherical equivalent refractive errors is associated with slower axial elongation wearing orthokeratology.

To investigate the relationship between axial length (AL) increase and baseline spherical equivalent refractive errors (SER) in myopic children wearing orthokeratology contact lenses (OK). One hundred fifteen Chinese (115 right eyes) children wearing OK were enrolled in this cohort study. Gender, age, baseline SER, corneal power, corneal astigmatism, and AL at baseline and 2 years after wearing OK were collected. Univariate analysis and trend test were used to estimate the relationship between change in AL and baseline SER. After univariate analysis, a statistically significant relationship was found between change in AL and baseline SER (β=0.061, 95% CI: 0.015-0.111, P=0.015). In the trend test, after adjusting for potential confounders, higher SER was associated with smaller increases in AL (P trend=0.041). The SER at baseline was associated with AL growth in myopic children wearing OK. The higher SER was associated with slower AL growth and control the development of myopia.

Evaluation of Optical Quality After Orthokeratology Contact Lens Wear

Evaluation of Optical Quality After Orthokeratology Contact Lens Wear

Two Cases of Corneal Toxicity inAcanthamoebaKeratitis by Combined Topical Anti-AcanthamoebaKeratitis Eye Solution

Purpose: To present a case of corneal toxicity caused by therapeutic duplication during treatment of acanthamoeba keratitis as a complication of contact lens use. Case summary: A 12-year-old girl with a history of wearing orthokeratology contact lenses and a 14-year-old girl with a history of wearing cosmetic contact lenses presented with ocular pain, injection, and decreased visual acuity. They were diagnosed as having acanthamoeba keratitis based on slit lamp examination, confocal microscopy and culture. After the patients were treated with polyhexamethylene biguanide (PHMB) and chlorhexidine, corneal epithelial defect and erosion occurred. Use of chlorhexidine was stopped, and PHMB was used to treat patients and recovery of the corneal epithelium with improvement in symptoms of acanthamoeba keratitis was found. Conclusions: Using PHMB and chlorhexidine together in treating acanthamoeba keratitis increases the risk of corneal toxicity. Therefore, these drugs should be avoided in combination. J Korean Ophthalmol Soc 2015;56(2):280-284

Factors Preventing Myopia Progression with Orthokeratology Correction

To examine which baseline measurements constitute predictive factors for axial length growth over 2 years in children wearing orthokeratology contact lenses (OK) and single-vision spectacles (SV). Sixty-one children were prospectively assigned to wear either OK (n = 31) or SV (n = 30) for 2 years. The primary outcome measure (dependent variable) was axial length change at 2 years relative to baseline. Other measurements (independent variables) were age, age of myopia onset, gender, myopia progression 2 years before baseline and baseline myopia, anterior chamber depth, corneal power and shape (p value), and iris and pupil diameters as well as parental refraction. The contribution of all independent variables to the 2-year change in axial length was assessed using univariate and multivariate regression analyses. After univariate analyses, smaller increases in axial length were found in the OK group compared to the SV group in children who were older, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had less myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris diameter, had larger pupil sizes, and had lower levels of parental myopia (all p < 0.05). In multivariate analyses, older age and greater corneal power were associated with smaller increases in axial length in the OK group (both p < 0.05), whereas in SV wearers, smaller iris diameter was associated with smaller increases in axial length (p = 0.021). Orthokeratology is a successful treatment option in controlling axial elongation compared to SV in children of older age, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had lower myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris and pupil diameters, and had lower levels of parental myopia.

Changes in Corneal Biometry and the Associated Histology in Rhesus Monkeys Wearing Orthokeratology Contact Lenses

This study compared the effect of orthokeratology (OK) lens wear on corneal topography and microstructure between the 1-night and 30-night wearers to predict any adverse responses of the eyes to long-term OK lens wear. Nine rhesus monkeys with one eye wearing an OK lens and the fellow eye wearing a rigid gas permeable (RGP) lens were used in this study. The lenses were worn for 11 hours, with the measurement of corneal curvature and thickness and axial components of the eye at 0 night (n = 9), 1 night (n = 9), and 30 nights (n = 6). Histology was performed at 1 and 30 nights of lens wear. Corneal surface power in the 3-mm central region was reduced in the OK eye when compared with the RGP eye (P < 0.05). Central corneal thickness was only reduced in 30 nights of OK lens wear (P < 0.05). Under light microscopy, the 1-night OK or RGP eyes showed normal morphology in all layers of the cornea. The 30-night OK eyes showed a thinned central corneal epithelium and a thickened but less stratified paracentral corneal epithelium when compared with the 30-night RGP eyes. Under electron microscopy, intercellular junctions of corneal epithelium in the 30-night OK eyes were much looser than those in the 1-night OK eyes. However, the density and morphology of hemidesmosomes were similar between the OK and RGP eyes at 30 nights of lens wear. Overnight OK can change the corneal curvature through anterior corneal remodeling, resulting in an effective correction of myopia. However, a decrease in intercellular junctions during long-term wear may compromise the functions of the corneal epithelium as a border mechanical barrier.

Myopia Control with Orthokeratology Contact Lenses in Spain: Refractive and Biometric Changes

To compare axial length growth between white children with myopia wearing orthokeratology contact lenses (OK) and distance single-vision spectacles (SV) over a 2-year period. Subjects 6 to 12 years of age with myopia -0.75 to -4.00 diopters of sphere (DS) and astigmatism ≤1.00 diopters of cylinder (DC) were prospectively allocated OK or SV correction. Measurements of axial length (Zeiss IOLMaster), corneal topography, and cycloplegic refraction were taken at 6-month intervals. Thirty-one children were fitted with OK and 30 with SV. Following 24 months, axial length increased significantly over time for both the OK group (0.47 mm) and SV group (0.69 mm; P < 0.001), with a significant interaction between time and group (P = 0.05) reflecting a greater increase in the SV group. Significant differences in refraction were found over time, between groups and for the interaction between time and group for spherical (all P < 0.001) but not cylindrical components of refraction (all P > 0.05). Significantly greater corneal flattening was evident in the OK group for the flatter and steeper corneal powers and for corneal shape factor (all P ≤ 0.05). Orthokeratology contact lens wear reduces axial elongation in comparison to distance single-vision spectacles in children.

Epithelial, Stromal, and Corneal Pachymetry Changes during Orthokeratology

To describe epithelial, stromal, and corneal thickness profile changes induced by orthokeratology treatment. This is a case report of a mild myopic patient (OD -3.25/-0.50 x 172 and OS -3.25/-0.50 x 45) treated with orthokeratology lenses. The patient was assessed before treatment (following 2 weeks of no orthokeratology contact lens wear) and during treatment (after 30 consecutive nights of wearing orthokeratology lenses). Epithelial, stromal, and corneal thickness profile in vivo was measured by Artemis very high-frequency digital ultrasound scanning across the central 10 mm diameter of the cornea before and during orthokeratology treatment. Manifest refraction, contrast sensitivity, corneal topography, and corneal front surface aberrations were also measured before and during orthokeratology treatment. Thickness changes were correlated with corneal topography changes and corneal front surface aberrations changes. The effects of these changes on the patient's quality of vision were measured with manifest refraction and contrast sensitivity. Orthokeratology lenses effectively corrected the patient's myopic refraction. Corneal topography demonstrated typical central flattening and an annulus of mid-peripheral steepening in both the eyes. The epithelial thickness profile was altered, with up to 18 microm of central epithelial thinning and up to 16 microm of annular mid-peripheral epithelial thickening. There also appeared to be a degree of stromal changes, with central stromal thickening and mid-peripheral stromal thinning, in particular in the left eye. There was a large increase in higher order aberrations, in particular in the left eye. This was associated with a decrease in contrast sensitivity in both the eyes. Refractive changes during orthokeratology treatment are mainly induced by changes in epithelial thickness profile, while stromal changes may also contribute to a small extent.

Myopia Control with Orthokeratology Contact Lenses in Spain (MCOS): Study Design and General Baseline Characteristics

Purpose Although previous studies suggest that orthokeratology contact lens wear slows eye growth in children with progressing myopia, some limitations in the methodology employed have become evident. Furthermore, the safety of this modality of visual correction has not been assessed. The study “Myopia Control with Orthokeratology Contact Lenses in Spain” (MCOS) is being conducted to compare axial length growth between white European myopic children wearing orthokeratology contact lenses (OK) and wearing distance single-vision spectacles (SV). Additionally, the incidence of adverse events and discontinuations is also recorded. We outline the methodology and baseline data adopted. Methods Subjects aged 6 to 12, with myopia ranging from 0.75 to 4.00 D and astigmatism ≤1.00 D were prospectively allocated OK or SV correction. Measurements of axial length, anterior chamber depth, corneal topography, cycloplegic autorefraction, visual acuity and corneal staining are performed at 6-month intervals. The incidence of adverse events and discontinuations are also recorded. Results Thirty one children were fitted with OK and 31 with SV correction. Eight subjects did not meet the refraction-related inclusion criteria for enrollment. No significant differences were found in baseline mean age and refractive and biometric data betwseen the two groups ( P>0.05). No adverse events were found in any of the two groups at baseline. Conclusion To the authors’ knowledge, MCOS is the first prospective clinical trial to assess the safety and efficacy of orthokeratology contact lens wear to slow myopia progression vs. single-vision spectacle wear. The MCOS offers a number of notable features: prospective design; well-matched samples and high-resolution ocular biometry measures, which should collectively elucidate whether orthokeratology contact lens wear is a feasible and safe method for myopia-progression control.

Trends in Microbial Keratitis Associated With Orthokeratology

Orthokeratology is a clinical technique that uses reverse-geometry rigid gas-permeable contact lenses to alter corneal shape to provide temporary reduction of refractive error. Microbial keratitis is the most severe, potentially vision-threatening adverse response associated with orthokeratology contact lens wear. This article aims to review all reported cases of confirmed and presumed microbial keratitis associated with orthokeratology and to examine trends in microbial keratitis in orthokeratology over time. Cases of microbial keratitis associated with orthokeratology were identified from case reports published in the optometric, ophthalmologic, and vision science literature and published in abstract form for papers or posters presented at optometric or ophthalmologic conferences. A total of 123 cases of microbial keratitis associated with orthokeratology have been reported since 2001, dating back to 1997. Most patients were female, East Asian, and aged between 8 and 15 years. The infectious organism was implicated as Pseudomonas aeruginosa for 46 (38%) of these cases and as Acanthamoeba species for 41 (33%) cases. The peak year for occurrence of microbial keratitis was 2001 and accounted for more than half (64 [52%] of 123) of all reported cases. All cases in this year were reported from East Asia, including China (47 cases), Taiwan (11 cases), and Hong Kong (6 cases). Although there has been an increasing number of reports of microbial keratitis associated with orthokeratology since 2001, most (85 [69%] of 123) of these cases occurred in East Asia, particularly in China and Taiwan, during a relatively short period, when regulation of this modality was limited. The high prevalence of cases of Acanthamoeba keratitis reported with this modality emphasizes the importance of eliminating the use of tap water in care regimens for overnight orthokeratology.

A Case of Fungal Keratitis as a Complication of Orthokeratology Contact Lens

Purpose: To present a case report of fungal keratitis related to prolonged overnight use of orthokeratology contact lenses. Methods: A 13 year-old girl presented with a corneal ulcer in her left eye refractory to antibacterial medication. She had a history of wearing orthokeratology contact lenses overnight for seven months. Results: The organism Aspergillus was isolated by corneal scraping, the contact lens itself, and from the storage case. The patient was treated with topical fluconazole and Natamycin pimaricin in addition to oral itraconazole, resulting in a resolution of the ocular lesion. Conclusions: The risk of fungal infection as a potential complication of the use of overnight orthkeratology contact lenses should be considered when using these lenses.