Analysis of Two Orthokeratology Lens Designs and Comparison of Their Optical Effects on the Cornea

Marcotte-Collard, Rémy; Simard, Patrice; Michaud, Langis

doi:10.1097/icl.0000000000000495

Cited by 35 publications

(34 citation statements)

References 17 publications

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“…Changes in the topographic profile, including a wider, steeper midperipheral ring, and closer to the pupil center, has been hypothesized as an important factor in improving the efficacy of myopia control with OrthoK lenses [24, 27, 32]. In a study published in 2016, Kang et al suggested that inducing greater degrees of myopic defocus on the peripheral retina, more than what is habitually experienced in a typical OrthoK lens, may be required for effective myopia control [33].…”

Section: Discussionmentioning

confidence: 99%

The Topographical Effect of Optical Zone Diameter in Orthokeratology Contact Lenses in High Myopes

Carracedo

Espinosa-Vidal

Martínez-Alberquilla

et al. 2019

Journal of Ophthalmology

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Purpose To evaluate the effect of the optical zone diameter (OZ) in orthokeratology contact lenses regarding the topographical profile in patients with high myopia (−4.00 D to −7.00 D) and to study its effect over the visual quality. Materials and Methods Twelve patients (18 eyes) were fitted with overnight orthokeratology (OrthoK) with a randomized 6 mm or 5 mm OZ lens worn for 2 weeks, followed by a 2-week washout period, between both designs. Keratometry (K) readings, optical zone treatment diameter (OZT), peripheral ring width (PRW), higher-order aberrations (HOA), high (HC) and low contrast (LC) visual acuity, and subjective vision and comfort were measured at baseline and after 2 weeks of OrthoK lens wear of each contact lens. Results No significant differences were found between any measurements for the same subject at both baselines (p value > 0.05). There was no difference between OZ lens designs found in refraction, subjective vision or comfort, and HC and LC visual acuity. Contrast sensitivity was decreased in the 5 mm OZ lens design compared with 6 mm OZ design (p-value < 0.05). 5 mm OZ design provoked a greater flattening, more powerful midperipheral ring and 4th-order corneal and total spherical aberration than the 6 mm OZ design, being statistically significant after 7 days, for corneal aberration, and 15 days, for corneal and total, of wearing the lens (p-value < 0.05). The OZT obtained were 2.8 ± 0.2 mm and 3.1 ± 0.1 mm for 5 mm and 6 mm OZ design, respectively (p-value < 0.05). Regarding PRW, the 5 mm OZ design had a wider ring width in both the nasal and temporal zones (p-value < 0.05). Conclusions A smaller diameter optical zone (5 mm) in orthokeratology lenses produces a smaller treatment area and a larger and more powerful midperipheral ring, increasing the 4th-order spherical aberration that affects only the contrast sensitivity but without differences in visual acuity and subjective vision compared with a larger OZ diameter (6 mm).

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Section: Discussionmentioning

confidence: 99%

The Topographical Effect of Optical Zone Diameter in Orthokeratology Contact Lenses in High Myopes

Carracedo

Espinosa-Vidal

Martínez-Alberquilla

et al. 2019

Journal of Ophthalmology

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“…263 More recently, a retrospective study found that participants fit with a four-curve OK lens design demonstrated a significantly larger central distance zone of treatment compared with a five-curve lens design, but there was no difference in the power or width of the midperipheral steepened zone, and the effect on relative peripheral refraction was not measured. 264 This is an area for further research.…”

Section: Future Research Directions On Intervention and Treatment 71mentioning

confidence: 95%

IMI – Clinical Management Guidelines Report

Gifford

Richdale

Kang

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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131

169

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Best practice clinical guidelines for myopia control involve an understanding of the epidemiology of myopia, risk factors, visual environment interventions, and optical and pharmacologic treatments, as well as skills to translate the risks and benefits of a given myopia control treatment into lay language for both the patient and their parent or caregiver. This report details evidence-based best practice management of the pre-, stable, and the progressing myope, including risk factor identification, examination, selection of treatment strategies, and guidelines for ongoing management. Practitioner considerations such as informed consent, prescribing off-label treatment, and guides for patient and parent communication are detailed. The future research directions of myopia interventions and treatments are discussed, along with the provision of clinical references, resources, and recommendations for continuing professional education in this growing area of clinical practice.

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“…The back optic zone diameter and reverse curve width of an ortho-k lens influence the treatment zone diameter and the surrounding annulus of mid-peripheral steepening, respectively. Manipulation of the back optic zone diameter or reverse curve width (by ≤1 mm) can produce significant variations in anterior corneal optics [79,345], with a smaller back optic zone diameter generating more relative peripheral corneal steepening and positive spherical aberration [346]. However, these lens modifications may not significantly alter peripheral refraction [74,307].…”

Section: Treatment Zone Sizementioning

confidence: 99%

BCLA CLEAR - Orthokeratology

Vincent

Cho

Chan³

et al. 2021

Contact Lens and Anterior Eye

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103

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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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Analysis of Two Orthokeratology Lens Designs and Comparison of Their Optical Effects on the Cornea

Abstract: The four- and five-curve orthokeratology lens designs generate significantly different optical modifications on the cornea. This can affect reports on orthokeratology efficacy for myopia management as well as the lens selection when used for myopia correction.

Cited by 35 publications

References 17 publications

The Topographical Effect of Optical Zone Diameter in Orthokeratology Contact Lenses in High Myopes

The Topographical Effect of Optical Zone Diameter in Orthokeratology Contact Lenses in High Myopes

IMI – Clinical Management Guidelines Report

BCLA CLEAR - Orthokeratology

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