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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Comparing short sighted refraction profiles created by two different designs of an orthokeratology contact lens
Scientific title
Changes in peripheral optics with two different orthokeratology lens designs for patients with myopia
Secondary ID [1] 293927 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Myopia 306415 0
Condition category
Condition code
Eye 305503 305503 0 0
Diseases / disorders of the eye

Study type
Description of intervention(s) / exposure
Two different orthokeratology lens designs are to be worn in randomised order for a period of 1 week overnight wear each, after which purposely induced changes to corneal shape and associated effect on refraction profile will be measured and compared, with a minimum 1 week duration washout period between the two iterations where no lenses will be worn. Each iteration will be worn overnight only in both eyes for a minimum of 5 hours and maximum of 12 hours.The orthokeratology lenses will be fitted by university researchers under the direct supervision of qualified University of New South Wales (UNSW), Sydney, employed optometrists. Participants will be required to self insert the lenses at their home before sleep and remove them on waking, with all training and support on how to insert and remove lenses and deal with any lens adherence provided. After each week of overnight wear participants will be required to return to UNSW for study measurements. Participants will be required to attend the study centre after the first night of lens wear to assess lens fit and to ensure that participants are successful in removing the lenses and in taking the correct cleaning and storage steps unguided. Participants will not be allowed to continue with the study until they are competent at removing and caring for the lenses without guidance. In the unlikely case that a participant has found the lens to be bound and can't be loosened with the resolution steps provided they will be instructed to contact the investigators for advice.
Intervention code [1] 300194 0
Treatment: Devices
Comparator / control treatment
Double blind repeated measures design with each of the two orthokeratology lens designs issued for wear in a randomised order. No need for a control group.
Control group

Primary outcome [1] 304635 0
Changes to anterior eye shape profile will be measured using a Medmont E300 corneal topographer.
Timepoint [1] 304635 0
In the morning before starting wear and in the morning after 7 nights of wear for each of the two orthokeratology lens designs being investigated.
Secondary outcome [1] 342635 0
Changes to peripheral refraction will be measured across the horizontal meridian using the Shin_Nippon NVisionK 5001 autorefractor
Timepoint [1] 342635 0
In the morning before starting wear and in the morning after 7 nights of wear for each of the two orthokeratology lens designs being investigated.

Key inclusion criteria
1. Healthy individuals aged between 18-40
2. Have short-sightedness (myopia) between -1.ooD and -4.ooD and less than -1.50D of corneal astigmatism
3. No previous rigid contact lens wear
4. Have good ocular health and general health
5. No contraindications to rigid contact lens wear
Minimum age
18 Years
Maximum age
40 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Strabismus or amblyopia
2. Systemic or ocular conditions that may affect tear quality or contact lens wear or that may affect refractive development
3. Previous history or ocular surgery, trauma, or chronic ocular disease
4. Ocular or systemic medication use that may interfere with contact lens wear or ocular surface
5. Not willing to comply with the allocated treatment and follow-up scheduole

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The order of wear for the two orthokeratology lens designs will be controlled by off-site by the contact lens lab providing the lenses. The lab will issue both sets of orthokeratology lenses in identical packets other than one being marked 'first to be worn' and the other 'second to be worn'. Order of allocation will be recorded by the lab and issued to the researcher conducting data analysis once all participants have completed the study. For an additional layer of clarification each orthokeratology lens will be engraved by the lab with a unique number that will be recorded by the researcher recording the study measurements so that at data analysis stage the lenses actually worn according to researcher observation can be cross referenced to the lens supply schedule recorded by the lab.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Prior data indicate that to conduct a study that is able to detect a difference of 0.1 D in mid-peripheral corneal refractive power, with a study power of 0.80 at the 5% level of statistical significance and taking into consideration a 20% drop out rate, 15 subjects will be required for this study. The Type I error probability associated with this test of this null hypothesis is 0.05. Repeated measures t-tests will be used to compare change to corneal shape profile and peripheral refraction profile over the 1 week wearing period of overnight wear between the two orthokeratology lens designs.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 298554 0
Name [1] 298554 0
University of New South Wales
Address [1] 298554 0
School of Optometry and Vision Science, University of New South Wales, Gate 14, Barker St, Rupert Myers Building (North Wing), Kensington, NSW, 2033
Country [1] 298554 0
Primary sponsor type
University of New South Wales
School of Optometry and Vision Science, University of New South Wales, Gate 14, Barker St, Rupert Myers Building (North Wing), Kensington, NSW, 2033
Secondary sponsor category [1] 297702 0
Name [1] 297702 0
Address [1] 297702 0
Country [1] 297702 0

Ethics approval
Ethics application status
Ethics committee name [1] 299523 0
UNSW Human Research Ethics Committee
Ethics committee address [1] 299523 0
UNSW Research Ethics & Compliance Support
University of New South Wales
Gate 14, Barker St
Rupert Myers Building (South Wing)
Kensington, NSW, 2033
Ethics committee country [1] 299523 0
Date submitted for ethics approval [1] 299523 0
Approval date [1] 299523 0
Ethics approval number [1] 299523 0

Brief summary
Myopia (short sightedness) is a refractive condition where the distance from the front to the back of the eye is too long for the refractive strength of the eye, leading to light being focussed in front of the retina (light sensitive layer on the inside back of the eye) and subsequently causing blurred vision. Myopia typically develops in childhood while the eye is growing and is believed to be accelerated by correcting the myopia with glasses. When myopia first presents the child complains of poor distance vision which is corrected by glasses. Unfortunately, myopia continues to progress requiring the child to return at regular intervals to get ever stronger glasses, until they reach adulthood.

Orthokeratology (OK) lenses are specialised contact lenses that are worn during sleep to reshape the front surface of the eye to temporarily correct myopia. Recent research has shown that OK lenses are effective at slowing progression of myopia by 50%. These encouraging results have led contact lens manufacturers to develop OK lens designs with greater effectivity in slowing progression of myopia. While these ‘Myopia Control’ OK lenses are now being supplied to optometry practices and marketed as being more effective in slowing progression of myopia compared to standard OK lens designs, there is no scientific evidence to support that they are any more effective than standard OK designs.

The aim of this project is to increase understanding on how myopia control OK lens designs will affect known stimuluses for myopia progression compared to standard OK lens designs. The scientific literature reveals that OK causes peripheral light rays to be focussed further towards the front of the eye than central light rays, which is termed peripheral myopic defocus. Peripheral myopic defocus has been shown to slow progression of myopia in animal models, and this same mechanism is believed to be the reason why OK lenses slow progression of myopia. The manufacturers of myopia control OK lens designs claim that they are more effective at slowing progression of myopia compared to standard OK lens designs because they create a greater amount of peripheral myopic defocus.

We are going to investigate the potential for greater slowing of myopia progression with myopia control OK lens designs, by measuring the effect that the different OK designs have on myopic defocus in young adults over 1 week of wear, which is the reported shortest duration of time for the full refractive effect to be achieved. This study is important as optometrists need to know the true effect that OK lenses marketed to slow myopia progression have on refractive mechanisms that have been shown to retard progression of myopia, if they are to be effective in managing myopia in their child patients. Outcomes will also assist the design of future longitudinal studies using standard and myopia control OK lens designs.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 80714 0
Dr Paul Gifford
Address 80714 0
School of Optometry and Vision Science University of New South Wales
Gate 14, Barker St
Rupert Myers Building (North Wing) Kensington, NSW, 2033
Country 80714 0
Phone 80714 0
Fax 80714 0
Email 80714 0
Contact person for public queries
Name 80715 0
Dr Paul Kang
Address 80715 0
School of Optometry and Vision Science University of New South Wales
Gate 14, Barker St
Rupert Myers Building (North Wing) Kensington, NSW, 2033
Country 80715 0
Phone 80715 0
+61 2 9385 9816
Fax 80715 0
Email 80715 0
Contact person for scientific queries
Name 80716 0
Dr Paul Gifford
Address 80716 0
School of Optometry and Vision Science University of New South Wales
Gate 14, Barker St
Rupert Myers Building (North Wing) Kensington, NSW, 2033
Country 80716 0
Phone 80716 0
Fax 80716 0
Email 80716 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Subject data is de-personalised.
What supporting documents are/will be available?
No other documents available
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