Retardation of Myopia in Orthokeratology

Study Overview
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Brief Summary
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The primary aim of this study is to evaluate and compare the eyeball elongation in children wearing orthokeratology lenses and single-vision spectacles.

Detailed Description
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Prevalence of myopia is high in Asian countries like Hong Kong. Orthokeratology has shown potential in slowing myopic progression but the efficacy is yet to be confirmed by a randomized clinical trial (RCT). The current RCT aims at studying the efficacy of orthokeratology in retardation of myopic progression by comparing the eye growth in terms of axial length elongation in children wearing orthokeratology lenses (study group) and those wearing single-vision spectacles (control group).

Official Title
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Orthokeratology for Myopic Control in Chinese Children - a Randomized Clinical Trial

Conditions
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Myopia

Intervention / Treatment
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* Device: orthokeratology lenses
* Device: single-vision spectacle lenses


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Myopia (refractive sphere): > 0.50D and ≤ 4.00D Astigmatism: < ½ of myopia; with-the-rule astigmatism (axes 180 +/- 30) ≤1.25D; astigmatism of other axes ≤ 0.50D Spherical equivalent (SE): > 0.75D and ≤ 4.50D Anisometropia: ≤ 1.50D in both refractive sphere, refractive cylinder and SE Best corrected monocular visual acuity: equal to or better than 0.10 in logMAR scale in both eyes Willingness for randomization Willingness to wear contact lenses or spectacles on a daily basis Availability for follow-up for at least 2 years Exclusion Criteria: Strabismus at distance or near Contraindication for contact lens wear and orthokeratology (e.g. limbus to limbus corneal cylinder and dislocated corneal apex Prior experience with the use of rigid lenses (including orthokeratology) Prior experience with myopia control treatment (e.g. refractive therapy or progressive add spectacles) Systemic or ocular conditions which may affect contact lens wear (e.g. allergy and medication) Systemic or ocular conditions which may affect refractive development (e.g. Down syndrome, ptosis)

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 10 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: orthokeratology lenses<br>Children wearing orthokeratology at night for correcting of refractive error will be study group | Device: orthokeratology lenses<br>* Nightly use of orthokeratology to correct the refractive error for a period of two years<br>* Other names: Menicon Z Night Lens;|
| Other: single-vision spectacle lenses<br>Children wearing single-vision spectacles in the daytime for correcting the refractive error will serve as control group | Device: single-vision spectacle lenses<br>* Daily use of spectacles to correct the refractive error for a period of two years<br>* Other names: CR-39 lenses;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Axial Elongation in the Study and Control Subjects Who Completed the Two Years Study | Axial elongation was determined by the change in axial length of the eyeball before and after treatment period. Axial length was measured by the IOLMaster (Zeiss Humphrey, Dublin, CA) 30 minutes after cycloplegia. The measurement of the axial length followed the procedures as recommended by the manufacturer. | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Determine the Incidence of Adverse Effects in Cornea, the Palpebral, Bulbar and Tarsal Conjunctiva in the Study and the Control Groups |  | 2 years | 
| Determine Changes in Other Ocular Parameters (e.g. Corneal Biomechanics and Aberration) Associated With Orthokeratology Lens Wear |  | 2 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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children, corneal reshaping, myopia, myopia control, orthokeratology