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Trial registered on ANZCTR


Registration number
ACTRN12611000499987
Ethics application status
Approved
Date submitted
11/05/2011
Date registered
12/05/2011
Date last updated
16/01/2012
Type of registration
Prospectively registered

Titles & IDs
Public title
Overnight contact lens treatment for myopia (short-sight) progression in children
Scientific title
Duplex orthokeratology (DOK) and myopia progression in children.
Secondary ID [1] 259740 0
NiL
Universal Trial Number (UTN)
U1111-1119-7694
Trial acronym
DOK
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Juvenile-onset progressive myopia. 265838 0
Condition category
Condition code
Eye 259470 259470 0 0
Diseases / disorders of the eye

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
A duplex orthokeratology lens will be worn overnight every night for 18 months in one eye by children with progressing myopia. A duplex orthokeratology lens has a dual focus optic zone which moulds the cornea so as to correct myopia and to simultaneously produce myopic retinal defocus.
Intervention code [1] 264171 0
Treatment: Devices
Comparator / control treatment
Conventional orthokeratology lens worn overnight, every night for 18 months in the contralateral eye.
Control group
Active

Outcomes
Primary outcome [1] 262281 0
The primary outcome measure is the difference in vitreous chamber depth in the eye treated with the experimental lens compared with the eye that is wearing the conventional orthokeratology lens. To measure vitreous chamber depth we will use non-contact Optical Low-Coherence Reflectometry (Lenstar LS 900, Haag Streit, Switzerland).
Timepoint [1] 262281 0
Outcome measurements will be performed at 0/6/12/18 months
Secondary outcome [1] 273453 0
Secondary outcome measurements are magnitude of central and peripheral refractive error measured with an open field autrefractor (Shin Nippon NVision K5001).
Timepoint [1] 273453 0
Secondary outcome measurements will be performed at 0/6/12/18 month
Secondary outcome [2] 276277 0
Amplitude of accommodation will be measured with an open field autrefractor (Shin Nippon NVision K5001) while the participant is looking at a near target.
Timepoint [2] 276277 0
Measurements will be performed at 0/6/12/18 month
Secondary outcome [3] 276278 0
Contrast sensitivity will be measured using a Pelli-Robson contrast sensitivity chart.
Timepoint [3] 276278 0
Measurements will be performed at 0/6/12/18 month

Eligibility
Key inclusion criteria
Age, 10 to 14 years at entry; Gender, both; Ethnicity, not selected (any); Spherical equivalent refraction (SER) between -1.25D to -4.00D; Corneal astigmatism <1.50D; Anisometropia <1.00D; Myopia progression of at least 0.50 D in the previous year; Best corrected acuity of 6/6 or better in both eyes; Good ocular and general health. The child and their parents should be able to communicate in English.
Minimum age
10 Years
Maximum age
14 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Active eye disease including Keratoconus; Recent rigid contact lens wear; Previous corneal surgery; Systemic disease which may influence visual acuity; Severe dry eye symptoms; Medication which could influence ocular health.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The random allocations to groups will be placed in sealed envelopes. These envelopes will be kept by the optometry clinic receptionist, who is not involved in the study. After the participant is found eligible to be part of the study, the receptionist chooses an envelope according to gender and ethnicity of the participant, opens the envelope and tells the investigator the group allocation. The investigator has no access to the randomisation schedule.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Pseudo-random number generator. Children will be assigned to one of two groups (A and B) using pseudo-random permuted blocks design. We will use random block size of four or six. Assignment randomization will be stratified by two categories, gender and ethnicity (East Asian and Other, including New Zealand European, Indian and Maori/Pacifica) to ensure that the number of children, the gender and ethnicity are balanced within the groups and remain approximately equal as children are recruited. Children in Group A will wear the DOK lens in their dominant eye: children in Group B will wear the DOK lens in their non-dominant eye.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Other
Other design features
Paired-eye comparison
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment outside Australia
Country [1] 3293 0
New Zealand
State/province [1] 3293 0

Funding & Sponsors
Funding source category [1] 264619 0
University
Name [1] 264619 0
The University of Auckland, Department of Optometry and Vision Science
Address [1] 264619 0
85 Park Road
Grafton
Auckland 1023
Country [1] 264619 0
New Zealand
Primary sponsor type
University
Name
The University of Auckland, Department of Optometry and Vision Science
Address
85 Park Road
Grafton
Auckland 1023
Country
New Zealand
Secondary sponsor category [1] 263757 0
None
Name [1] 263757 0
Address [1] 263757 0
Country [1] 263757 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 260620 0
Lower South Regional Ethics Committee
Ethics committee address [1] 260620 0
c/- Ministry of Health
229 Moray Place
Dunedin 9016
Ethics committee country [1] 260620 0
New Zealand
Date submitted for ethics approval [1] 260620 0
15/02/2011
Approval date [1] 260620 0
14/03/2011
Ethics approval number [1] 260620 0
LRS/11/02/001

Summary
Brief summary
Scientific summary
Myopia (short-sight) is a condition in which close objects are seen clearly but distant objects appear blurred. The prevalence of myopia is very high in Asia (Seet, Wong et al. 2001) and is increasing in Europe, Australia and the U.S. (Kempen, Mitchell et al. 2004).

It has been shown in several animal species that ocular growth can be modified by retinal defocus (Smith, Kee et al. 2005). Hyperopic retinal defocus (image plane focused posterior to the retina) causes eye elongation, while myopic defocus (image plane focused anterior to the retina) causes a reduction in eye growth (Winawer and Wallman 2002). It has recently been suggested that in addition to correcting myopia, conventional OK may also slow the progressive eye elongation, which is the basis of myopia progression. The process of flattening the central cornea in conventional OK inevitably results in steepening the peripheral cornea. It has been hypothesised that the steepening in the peripheral cornea with OK may cause myopic retinal defocus in the peripheral retina, which may in turn slow myopia progression.

Another recent innovation, shown to be effective in slowing myopia progression is the Dual-Focus soft contact lens (Anstice 2009). This lens has a central correction zone with concentric treatment zones providing 2.00 dioptres of myopic defocus.

Duplex orthokeratology: We have designed a Duplex OK lens aimed at enhancing the efficacy of conventional OK in slowing progression by combining (adding) the optical treatment effect of the Dual-focus lens with the treatment effect of conventional OK lenses. The lens moulds the corneal surface into a correction zone in the centre surrounded by an annular treatment zone within the confines of the pupil, similar to a Dual-Focus contact lens. Evidence that the corneal surface can indeed be moulded in this way comes from the use of similar multi-zone orthokeratology lenses for presbyopia. The aim of this study is to test the efficacy of this new lens design in slowing myopia progression, using conventional OK as control.

Aim
The hypothesis is that progression of myopia (axial eye elongation) in eyes wearing the Duplex Orthokeratology (DOK) lens overnight will be reduced compared to eyes wearing a conventional orthokeratology (OK) lens overnight, over a period of 18 months. It is not possible to test this hypothesis on the basis of change in refraction because both DOK and conventional OK will correct refractive error in both eyes. In order to test the hypothesis we will compare changes in vitreous chamber depth (VCD) between the two eyes over time and the vitreous chamber depth difference will be the primary outcome measure.

Study Design
This is a prospective, randomized, paired-eye control, investigator-masked, single-centre trial. Thirty children will wear a conventional OK lens (randomly assigned) in one eye (control eye) and a Duplex OK lens in the contra-lateral (treatment) eye.

The study will be conducted with children aged between 10 to 14 years. During 18 months of lens wear, we will compare the elongation of vitreous chamber depth between the treatment and control eye measured at time 0, 6, 12 and 18 months. Elongation of vitreous chamber depth will be the outcome measurement that will directly show whether the DOK treatment is more effective than conventional OK. Vitreous chamber depth will be measured by low coherence reflectometry (Haag Streit Lenstar LS 900).

Secondary outcome measures will monitor the visual performance of each participant. These include refractive error, accommodation performance and contrast sensitivity with conventional and duplex orthokeratology.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 32314 0
Address 32314 0
Country 32314 0
Phone 32314 0
Fax 32314 0
Email 32314 0
Contact person for public queries
Name 15561 0
Martin Loertscher
Address 15561 0
c/- Department of Optometry and Vision Science The University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 15561 0
New Zealand
Phone 15561 0
+64 9 923 1352
Fax 15561 0
Email 15561 0
m.loertscher@auckland.ac.nz
Contact person for scientific queries
Name 6489 0
John Phillips PhD
Address 6489 0
c/- Department of Optometry and Vision Science The University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 6489 0
New Zealand
Phone 6489 0
+64 9 923 6073
Fax 6489 0
Email 6489 0
j.phillips@auckland.ac.nz

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary