Discontinuation of Lens Wear in New Ortho-k Children (DOEE2)

Not Applicable

Completed

Brief Summary: This study aims at investigating the efficacy of myopic control using ortho-k in younger and older children.

Detailed Description: Children wearing ortho-k have been shown to have slower rate of myopic progression than those wearing single-vision spectacles (Cho et al. 2005) or soft lenses (Walline et al. 2009). Younger myopic children (aged 6-10 years old) may have the faster increase in myopia than old myopic children (aged 11-15 years old), i.e. the rate of myopic progression may be different in different age groups and in children with different refractive status (Edwards 1999; Fan et al. 2004; Cheng et al. 2007). Although the refractive correction with ortho-k has been well documented, it is unknown whether the efficiency and reversibility of ortho-k for myopic reduction as well as myopic control are similar in children of different age and refractive groups.

In this 14-month study, the eyeball length in 45 younger (6-10 years old) and 45 older (11-15 years old) myopic children before and after ortho-k will be evaluated. Eyeball elongation will be determined for the first 7 months when single-vision glasses will be prescribed (Phase I) and the next 7 months when ortho-k will be prescribed (Phase I). Rate of myopic progression will be determined and compared between the two groups of children in the two phases.

Recruitment & Eligibility

Inclusion Criteria

Age: between 6 to 15 years old
Myopia: between 1.50D and 4.50D in at least one eye
Spherical equivalent (SE): between -1.00D to -4.50D in both eyes
Astigmatism: ≤ 3.00D of axes 180 +/- 30 or ≤ 1.00D of other axes; and the amount is less than refractive sphere
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 to wear contact lenses or spectacles on a daily basis
Can obtain good ortho-k results with the study lenses
Availability for follow-up for at least 14 months

Exclusion Criteria

Strabismus at distance or near
Contraindication for contact lens wear and ortho-k (e.g. limbus to limbus corneal cylinder and dislocated corneal apex
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)
Prior experience with the use of rigid lenses (including ortho-k)
Prior experience with myopia control treatment (e.g. refractive therapy or progressive spectacles)
Non-compliance to the follow up schedule
Non-compliance to the use of the prescribed optical correction
Poor ocular response to ortho-k lens wear
Significant residual refractive error after ortho-k treatment resulting in poor unaided vision (worse than 0.18 in logMAR scale)

Arm && Interventions

Group	Intervention	Description
ortho-k lenses	single-vision glasses	Children were switched to wear ortho-k lenses for 7 months after wearing single-vision glasses for 7 months
ortho-k lenses	ortho-k lenses	Children were switched to wear ortho-k lenses for 7 months after wearing single-vision glasses for 7 months

Primary Outcome Measures

Name	Time	Method
Change in Axial Elongation in the Two Study Phases	14 months	Axial elongation in children during the two study phases. Phase I: 7 months wearing single-vision spectacles. Phase II: 7 months wearing orthokeratology

Secondary Outcome Measures

Name	Time	Method
Number of Participants With Serious Adverse Effects	14 months	Number of subjects with serious adverse effects of the cornea, the palpebral, bulbar and tarsal conjunctiva