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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]

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.

Condition category

Condition code

Eye

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]

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]

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]

Outcome measurements will be performed at 0/6/12/18 months

Secondary outcome [1]

Contrast sensitivity will be measured using a Pelli-Robson contrast sensitivity chart.

Timepoint [1]

Measurements will be performed at 0/6/12/18 month

Secondary outcome [2]

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]

Measurements will be performed at 0/6/12/18 month

Secondary outcome [3]

Secondary outcome measurements are magnitude of central and peripheral refractive error measured with an open field autrefractor (Shin Nippon NVision K5001).

Timepoint [3]

Secondary outcome 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

Sex

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

20/05/2011

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]

New Zealand

State/province [1]

Funding & Sponsors

Funding source category [1]

University

Name [1]

The University of Auckland, Department of Optometry and Vision Science

Address [1]

85 Park Road
Grafton
Auckland 1023

Country [1]

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]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Lower South Regional Ethics Committee

Ethics committee address [1]

c/- Ministry of Health 
229 Moray Place 
Dunedin 9016

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

15/02/2011

Approval date [1]

14/03/2011

Ethics approval number [1]

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

Address

Country

Phone

Fax

Contact person for public queries

Name

Martin Loertscher

Address

c/- Department of Optometry and Vision Science The University of Auckland
85 Park Road
Grafton
Auckland 1023

Country

New Zealand

Phone

+64 9 923 1352

Fax

m.loertscher@auckland.ac.nz

Contact person for scientific queries

Name

John Phillips PhD

Address

c/- Department of Optometry and Vision Science The University of Auckland
85 Park Road
Grafton
Auckland 1023

Country

New Zealand

Phone

+64 9 923 6073

Fax

j.phillips@auckland.ac.nz

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Multifocal orthokeratology versus conventional orthokeratology for myopia control: A paired-eye study.	2021	https://dx.doi.org/10.3390/jcm10030447

N.B. These documents automatically identified may not have been verified by the study sponsor.

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