Retardation of Myopia in Orthokeratology

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

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

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).

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)