Myopia
Conditions
Keywords
children, corneal reshaping, myopia, myopia control, orthokeratology
Brief summary
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
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).
Interventions
DEVICEorthokeratology lenses
Nightly use of orthokeratology to correct the refractive error for a period of two years
Daily use of spectacles to correct the refractive error for a period of two years
Sponsors
Menicon Co., Ltd.
The Hong Kong Polytechnic University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Investigator)
Eligibility
Sex/Gender
ALL
Age
6 Years to 10 Years
Healthy volunteers
Yes
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)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Axial Elongation in the Study and Control Subjects Who Completed the Two Years Study | 2 years | 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. |
Secondary
| Measure | 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 |
Countries
China
Participant flow
Recruitment details
Phone screening was conducted on all parents who responded to advertisements in local newspapers during March 2008 and June 2009. Those who passed the screening would be invited to attend the baseline visit at the Optometry Clinic of The Hong Kong Polytechnic University.
Pre-assignment details
All subjects who passed the inclusion and exclusion criteria at the baseline visit would be assigend to the treatment according to the randomization log.
Participants by arm
| Arm | Count |
|---|---|
| Orthokeratology Lenses Study group: children were asked to wear orthokeratology lenses every night (Menicon Z Night Lens: Menicon Z material, DK 163 ISO; central lens thickness: 0.24 mm) to correct the refractive error during the study period. | 51 |
| Single-vision Spectacle Lenses Control group: children were asked to wear single-vision spectacles (CR-39 material with refractive index 1.56) in the daytime to correct the refractive error during the study period. | 51 |
| Total | 102 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Contraindicated to continue study | 5 | 1 |
| Overall Study | Could not achieve good vision | 9 | 0 |
| Overall Study | Lost to Follow-up | 0 | 9 |
Baseline characteristics
| Characteristic | Single-vision Spectacle Lenses | Orthokeratology Lenses | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 51 Participants | 51 Participants | 102 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 0 Participants | 0 Participants | 0 Participants |
| Age Continuous | 9.27 years STANDARD_DEVIATION 1.09 | 9.28 years STANDARD_DEVIATION 1.1 | 9.28 years STANDARD_DEVIATION 1.09 |
| Region of Enrollment China | 51 participants | 51 participants | 102 participants |
| Sex: Female, Male Female | 25 Participants | 25 Participants | 50 Participants |
| Sex: Female, Male Male | 26 Participants | 26 Participants | 52 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 51 | 0 / 51 |
| serious Total, serious adverse events | 0 / 51 | 0 / 51 |
Outcome results
Primary
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.
Time frame: 2 years
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Orthokeratology Lenses | Axial Elongation in the Study and Control Subjects Who Completed the Two Years Study | 0.36 mm | Standard Deviation 0.24 |
| Single-vision Spectacle Lenses | Axial Elongation in the Study and Control Subjects Who Completed the Two Years Study | 0.63 mm | Standard Deviation 0.26 |
Secondary
Determine Changes in Other Ocular Parameters (e.g. Corneal Biomechanics and Aberration) Associated With Orthokeratology Lens Wear
Time frame: 2 years
Secondary
Determine the Incidence of Adverse Effects in Cornea, the Palpebral, Bulbar and Tarsal Conjunctiva in the Study and the Control Groups
Time frame: 2 years