Investigation of the Effect of Short-term Orthokeratology With Increased Compression Factor on Ocular Parameters

• Sponsor: The Hong Kong Polytechnic University (Other)
• Overall Status: Completed
• CT.gov ID: NCT02643875
• Collaborator: Menicon Co., Ltd. (Industry), Queensland University of Technology (Other), Aston University (Other)
• Enrollment: 36
• Location: 1
• Arms: 2
• Actual Duration (Months): 8.7
• Patients Per Site Per Month: 4.1

Study Details

Study Description

Brief Summary

Orthokeratology (ortho-k) is a clinical technique that uses reverse geometry rigid gas permeable contact lens exerting positive pressure on the central cornea to temporary reduce refractive error. Researchers have shown that this treatment is effective for myopia control in low to high myopes, with and without astigmatism. Most designs of ortho-k lenses in the market are fitted based on the Jessen formula. The compression factor was introduced to compensate for the regression of the ortho-k effect during the no lens-wear period, so that the wearer can obtain clear distance vision throughout the day and most lens designs use a compression factor of 0.50-0.75 D. However, in a retrospective study (mixed brands of ortho-k lenses), it showed that most patients did not achieve an over-correction of 0.75 D. In order to achieve an over-correction of 0.75 D, an extra flattening power of about 1.50 D instead of 0.75 D should be be targeted. The increased compression factor is expected to increase the target reduction and it may play a role in myopic control and providing a higher successful rate in fitting ortho-k lenses.

Condition or Disease	Intervention/Treatment	Phase
Myopic Progression	Device: Orthokeratology	N/A

Detailed Description

Subjects were fitted with ortho-k lenses of conventional (0.75 D) and increased (1.75 D) compression factor. The laterality of the compression factor for each subject was randomised.

Subjects were instructed and trained with proper lens handling and disinfection procedures. Lenses were given to the subjects only when they demonstrated proper techniques.

All subjects were required to attend regular follow-ups (baseline, first overnight, and weekly over one-month period). The follow-ups were scheduled (except for the first overnight which was scheduled in the early morning) at a similar time to the baseline visit (+/- 2 hours) to minimise any potential influence of diurnal variation on ocular biometrics.

Additional unscheduled visits were provided when necessary to ensure good ocular health and vision throughout the study period.

Study Design

• Study Type: Interventional
• Actual Enrollment: 36 participants
• Allocation: Randomized
• Intervention Model: Single Group Assignment
• Masking: Double (Participant, Outcomes Assessor)
• Primary Purpose: Treatment
• Official Title: Investigation of the Effect of Short-term Orthokeratology With Increased Compression Factor on Ocular Parameters
• Actual Study Start Date: Feb 26, 2016
• Actual Primary Completion Date: Nov 18, 2016
• Actual Study Completion Date: Nov 18, 2016

Arms and Interventions

Arm	Intervention/Treatment
Sham Comparator: Ortho-k lens with normal compression factor The eye wears ortho-k lens with normal compression factor to achieve plano (+/- 0.25D) correction.	Device: Orthokeratology; It is a kind of rigid permeable lens.
Active Comparator: Ortho-k lenses with increased compression factor The eye wears ortho-k lenses with increased compression factor to achieve 1 diopter (+/- 0.25D) over correction.	Device: Orthokeratology; It is a kind of rigid permeable lens.

Outcome Measures

Primary Outcome Measures

1. Changes in Spherical Equivalent Refraction [baseline and one month]

   Maximum plus for maximum visual acuity was used as the criterion for subjective refraction. Spherical equivalent refraction was calculated by adding the sum of the sphere power with half of the cylinder power.

Secondary Outcome Measures

1. Changes in Subfoveal Choroidal Thickness [baseline and one month]

   The subfoveal choroidal thickness was determined as the thickness between the outer retinal pigment epithelium/Bruch's membrane complex and the inner chorioscleral interface.

2. Changes in Higher Order Aberrations [baseline and one month]

   Ocular higher order aberrations were measured using Shack-Hartmann aberrometer. The wavefront data was fitted with a sixth order Zernike polynomial over a 5-mm pupil size.

Eligibility Criteria

Criteria

• Ages Eligible for Study: 6 Years to 10 Years
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Inclusion Criteria:

1. 6 to 10 years old

2. Myopia: between 0.50 D and 4.00 D in both eyes

3. Astigmatism: <1.50 D; ≤ 1.25 D for with-the-rule astigmatism (axes 180 ± 30); ≤ 0.50 D for astigmatism of other axes in both eyes

4. Anisometropia: ≤ 1.50 D

5. Symmetrical corneal topography with corneal toricity <2.00 D in both eyes

6. Agree for randomization

Exclusion Criteria:

1. Contraindications for orthokeratology wear (e.g. limbus-to-limbus corneal cylinder and dislocated corneal apex)

2. Any type of strabismus or amblyopia

3. Myopic treatment (e.g. refractive surgery and progressive lens wear for myopic control) before and during the study period

4. Rigid contact lenses (including orthokeratology lenses) experience

5. Systemic condition which might affect refractive development (for example, Down syndrome, Marfan's syndrome)

6. Ocular conditions which might affect the refractive error (for example, cataract, ptosis)

7. Poor compliance for lens wear or follow-up

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	The Hong Kong Polytechnic University	Hong Kong		China

Sponsors and Collaborators

• The Hong Kong Polytechnic University
• Menicon Co., Ltd.
• Queensland University of Technology
• Aston University

Investigators

• Principal Investigator: Pauline Cho, PhD, The Hong Kong Polytechnic University

Study Documents (Full-Text)

None provided.

More Information

Publications

• Chan B, Cho P, Mountford J. The validity of the Jessen formula in overnight orthokeratology: a retrospective study. Ophthalmic Physiol Opt. 2008 May;28(3):265-8. doi: 10.1111/j.1475-1313.2008.00545.x.
• Chen C, Cheung SW, Cho P. Myopia control using toric orthokeratology (TO-SEE study). Invest Ophthalmol Vis Sci. 2013 Oct 3;54(10):6510-7. doi: 10.1167/iovs.13-12527.
• Cho P, Cheung SW, Edwards M. The longitudinal orthokeratology research in children (LORIC) in Hong Kong: a pilot study on refractive changes and myopic control. Curr Eye Res. 2005 Jan;30(1):71-80.
• Cho P, Cheung SW. Retardation of myopia in Orthokeratology (ROMIO) study: a 2-year randomized clinical trial. Invest Ophthalmol Vis Sci. 2012 Oct 11;53(11):7077-85. doi: 10.1167/iovs.12-10565.

• Responsible Party: Pauline Cho, Professor, The Hong Kong Polytechnic University
• ClinicalTrials.gov Identifier: NCT02643875
• Other Study ID Numbers: HSEARS20151002004
• First Posted: Dec 31, 2015
• Last Update Posted: Sep 18, 2020
• Last Verified: Feb 1, 2020

• Keywords provided by Pauline Cho, Professor, The Hong Kong Polytechnic University: myopia control; orthokeratology
• Additional relevant MeSH terms: Disease Progression

Study Results

Participant Flow

Pre-assignment Detail	All subjects who passed the inclusion and exclusion criteria at the baseline visit would be assigned to the treatment for each eye according to the randomization log.

Arm/Group Title	Orthokeratology Lenses With Different Compression Factors
Arm/Group Description	Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.
Period Title: Overall Study
STARTED	36
Received 0.75	36
Received 1.75 D	36
COMPLETED	28
NOT COMPLETED	8

Baseline Characteristics

Arm/Group Title	Orthokeratology Lenses With Different Compression Factors
Arm/Group Description	Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.
Overall Participants	28
Overall eyes	56
Age (years) [Mean (Full Range) ]
Mean (Full Range) [years]	9.3
Sex: Female, Male (Count of Participants)
Female	16 57.1%
Male	12 42.9%
Spherical equivalent refraction (D) [Mean (Standard Deviation) ]
Conventional compression factor (0.75 D)	2.12 (0.94)
Increased compression factor (1.75 D)	2.09 (0.97)

Outcome Measures

1. Primary Outcome

Title	Changes in Spherical Equivalent Refraction
Description	Maximum plus for maximum visual acuity was used as the criterion for subjective refraction. Spherical equivalent refraction was calculated by adding the sum of the sphere power with half of the cylinder power.
Time Frame	baseline and one month

Outcome Measure Data

Analysis Population Description

Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.

Arm/Group Title	Orthokeratology Lenses With Different Compression Factors
Arm/Group Description	Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.
Measure Participants	28
Measure eyes	56
Conventional compression factor (0.75 D)	2.31 (0.88)
Increased compression factor (1.75 D)	2.52 (0.85)

2. Secondary Outcome

Title	Changes in Subfoveal Choroidal Thickness
Description	The subfoveal choroidal thickness was determined as the thickness between the outer retinal pigment epithelium/Bruch's membrane complex and the inner chorioscleral interface.
Time Frame	baseline and one month

Outcome Measure Data

Analysis Population Description

Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.

Arm/Group Title	Orthokeratology Lenses With Different Compression Factors
Arm/Group Description	Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.
Measure Participants	28
Measure eyes	56
Conventional compression factor (0.75 D)	-1 (30)
Increased compression factor (1.75 D)	-6 (30)

3. Secondary Outcome

Title	Changes in Higher Order Aberrations
Description	Ocular higher order aberrations were measured using Shack-Hartmann aberrometer. The wavefront data was fitted with a sixth order Zernike polynomial over a 5-mm pupil size.
Time Frame	baseline and one month

Outcome Measure Data

Analysis Population Description

Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.

Arm/Group Title	Orthokeratology Lenses With Different Compression Factors
Arm/Group Description	Orthokeratology lenses with different compression factors (one eye with 0.75 D and the fellow eye with 1.75 D) were randomly assigned to each subject.
Measure Participants	28
Measure eyes	56
Conventional compression factor (0.75 D)	0.2830 (0.03)
Increased compression factor (1.75 D)	0.1870 (0.03)

Adverse Events

Time Frame	one month
Arm/Group Title	Conventional Compression Factor (0.75 D)		Increased Compression Factor (1.75 D)
Arm/Group Description	Orthokeratology lenses with conventional compression factor (0.75 D) were randomly assigned to one eye of each subject.		Orthokeratology lenses with increased compression factor (1.75 D) were randomly assigned to the fellow eye of each subject.
All Cause Mortality
	Conventional Compression Factor (0.75 D)		Increased Compression Factor (1.75 D)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/28 (0%)		0/28 (0%)
Serious Adverse Events
	Conventional Compression Factor (0.75 D)		Increased Compression Factor (1.75 D)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/28 (0%)		0/28 (0%)
Other (Not Including Serious) Adverse Events
	Conventional Compression Factor (0.75 D)		Increased Compression Factor (1.75 D)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/28 (0%)		0/28 (0%)

Limitations/Caveats

[Not Specified]

More Information

Certain Agreements

All Principal Investigators ARE employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.