Weekly Changes in Axial Length and Choroidal Thickness in Children During and Following Orthokeratology Treatment With Different Compression Factors

Lau, Jason K.; Wan, Kin; Cheung, Sin Wan; Vincent, Stephen J.; Cho, Pauline

doi:10.1167/tvst.8.4.9

Cited by 39 publications

(56 citation statements)

References 46 publications

(77 reference statements)

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“…The initial AL shortening after commencement of ortho-k treatment was significantly higher in the ICF group after 1 month of lens wear, which is in agreement with our previous study. 40 The anterior segment length has been shown to be unaffected by ortho-k lens wear 41 and CCT thinning in the ICF group only accounted for around 30% of the total AL shortening after 1 month of lens wear. The source of the remaining AL shortening was unclear, although it has been suggested to be due to thickening of the choroid.…”

Section: Ocular Characteristics Of the Ortho-k Subjects After 1 Month Of Lens Wearmentioning

confidence: 95%

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

et al. 2020

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ObjectiveTo present the study design and the baseline data of a prospective cohort study investigating the safety, refractive correction and effectiveness of myopia control in subjects fitted with orthokeratology (ortho-k) lenses of different compression factors.Methods and analysisThis study is a 2-year longitudinal, double-masked, partially randomised study. Myopic children aged between 6 and 10 years are recruited and they may choose to participate in either the ortho-k or spectacle-wearing group. Subjects in the ortho-k group are randomly assigned to wear ortho-k lenses of either conventional compression factor (CCF, 0.75 D) or increased compression factor (ICF, 1.75 D). For the ortho-k subjects, the time and between-group effects within the first month of lens wear were analysed.ResultsSixty-nine ortho-k subjects (CCF: 34; ICF: 35) and 30 control subjects were recruited. There were no significant differences in baseline demographic data among the three groups of subjects (p>0.19). At the 1-month visit, the first fit success rates were 97% and 100% in the CCF and ICF ortho-k group, respectively. A higher percentage of ICF subjects could achieve full correction (CCF: 88.2%; ICF: 94.3%). The change in axial length was significantly higher in the ICF group (CCF, 0.003 mm; ICF, −0.031 mm) (p<0.05). No significant between-group differences in daytime vision or in the coverage and depth of corneal staining between the two ortho-k groups (p>0.05) were observed at any visit.ConclusionICF did not compromise the corneal integrity and the lens centration within the first month of lens wear. The preliminary performance of ortho-k lenses with ICF of 1.00D shows that it was safe to be used in the longer term for the investigation of myopia control.Trial registration numberNCT02643342.

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Section: Ocular Characteristics Of the Ortho-k Subjects After 1 Month Of Lens Wearmentioning

confidence: 95%

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

et al. 2020

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“…An increase in axial growth has been reported when children, who had been using ortho-k for two years ceased lens wear, at or before the age of 14 years [273]. This is appears to be partially due to a thinning of the choroid in the post-treatment period [82]. However, on resuming lens wear, axial elongation significantly slowed again [273], suggesting that ortho-k may need to be continued throughout the years during which myopia is likely to progress.…”

Section: Ceasing Orthokeratology For Myopia Controlmentioning

confidence: 98%

“…However, large individual variations have been observed [80,81]. In children who wore ortho-k lenses to correct up to 4.00 D of myopia for either one [82] or 24 months [83], on average, corneal flattening and the change in SER had regressed by ~80 to 100% compared to pre-treatment values one week after ceasing lens wear. It should be noted that variations from the pre-treatment SER may be related to myopia progression in studies of six months or more in duration.…”

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confidence: 99%

BCLA CLEAR - Orthokeratology

Vincent

Cho

Chan³

et al. 2021

Contact Lens and Anterior Eye

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Orthokeratology (ortho-k) is the process of deliberately reshaping the anterior cornea by utilising specialty contact lenses to temporarily and reversibly reduce refractive error after lens removal. Modern ortho-k utilises reverse geometry lens designs, made with highly oxygen permeable rigid materials, worn overnight to reshape the anterior cornea and provide temporary correction of refractive error. More recently, ortho-k has been extensively used to slow the progression of myopia in children.This report reviews the practice of ortho-k, including its history, mechanisms of refractive and ocular changes, current use in the correction of myopia, astigmatism, hyperopia, and presbyopia, and standard of care. Suitable candidates for ortho-k are described, along with the fitting process, factors impacting success, and the potential options for using newer lens designs. Ocular changes associated with ortho-k, such as alterations in corneal thickness, development of microcysts, pigmented arcs, and fibrillary lines are reviewed. The safety of ortho-k is extensively reviewed, along with an overview of non-compliant behaviours and appropriate disinfection regimens. Finally, the role of ortho-k in myopia management for children is discussed in terms of efficacy, safety, and potential mechanisms of myopia control, including the impact of factors such as initial fitting age, baseline refractive error, the role of peripheral defocus, higher order aberrations, pupil size, and treatment zone size.

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“…Previous researchers had mentioned that the ortho-k lens plays its role mainly via the mechanical interaction between the lens and the cornea or the eyeball ( Swarbrick, 2004 ; Wan et al, 2020 ). Numerous studies ( Kobayashi et al, 2008 ; Lau et al, 2019 ; Mohidin et al, 2020 ; Queiros et al, 2020 ) had attempted to reveal the mechanical effect of wearing ortho-k lenses on the cornea by comparing the change of refractive states, corneal topographies, and corneal thicknesses before and after ortho-k treatment, but few researchers went into details of the analysis due to the complexity of measurement and calculation.…”

Section: Introductionmentioning

confidence: 99%

The Biomechanical Response of the Cornea in Orthokeratology

Fang

et al. 2021

Front. Bioeng. Biotechnol.

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Orthokeratology has been widely used to control myopia, but the mechanism is still unknown. To further investigate the underlying mechanism of corneal reshaping using orthokeratology lenses via the finite element method, numerical models with different corneal curvatures, corneal thicknesses, and myopia reduction degrees had been developed and validated to simulate the corneal response and quantify the changes in maximum stress in the central and peripheral corneal areas during orthokeratology. The influence of the factors on corneal response had been analyzed by using median quantile regression. A partial eta squared value in analysis of variance models was established to compare the effect size of these factors. The results showed central and peripheral corneal stress responses changed significantly with increased myopia reduction, corneal curvature, and corneal thickness. The target myopia reduction had the greatest effect on the central corneal stress value (partial eta square = 0.9382), followed by corneal curvature (partial eta square = 0.5650) and corneal thickness (partial eta square = 0.1975). The corneal curvature had the greatest effect on the peripheral corneal stress value (partial eta square = 0.5220), followed by myopia reduction (partial eta square = 0.2375) and corneal thickness (partial eta square = 0.1972). In summary, the biomechanical response of the cornea varies significantly with the change in corneal conditions and lens designs. Therefore, the orthokeratology lens design and the lens fitting process should be taken into consideration in clinical practice, especially for patients with high myopia and steep corneas.

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Weekly Changes in Axial Length and Choroidal Thickness in Children During and Following Orthokeratology Treatment With Different Compression Factors

Abstract: changes in axial length and choroidal thickness in children during and following orthokeratology treatment with different compression factors.

Cited by 39 publications

References 46 publications

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

Orthokeratology with increased compression factor (OKIC): study design and preliminary results

BCLA CLEAR - Orthokeratology

The Biomechanical Response of the Cornea in Orthokeratology

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