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

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ClinicalTrials.gov Identifier: NCT02643875
Recruitment Status : Completed
First Posted : December 31, 2015
Results First Posted : September 18, 2020
Last Update Posted : September 18, 2020
Sponsor:
Collaborators:
Menicon Co., Ltd.
Queensland University of Technology
Aston University
Information provided by (Responsible Party):
Pauline Cho, The Hong Kong Polytechnic University

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 Not Applicable

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.

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Study Type : Interventional  (Clinical Trial)
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 : February 26, 2016
Actual Primary Completion Date : November 18, 2016
Actual Study Completion Date : November 18, 2016

Resource links provided by the National Library of Medicine


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.




Primary Outcome Measures :
  1. Changes in Spherical Equivalent Refraction [ Time Frame: 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 [ Time Frame: 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 [ Time Frame: 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.



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Ages Eligible for Study:   6 Years to 10 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02643875


Locations
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China
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
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Principal Investigator: Pauline Cho, PhD The Hong Kong Polytechnic University
Publications of Results:
Other Publications:
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Responsible Party: Pauline Cho, Professor, The Hong Kong Polytechnic University
ClinicalTrials.gov Identifier: NCT02643875    
Other Study ID Numbers: HSEARS20151002004
First Posted: December 31, 2015    Key Record Dates
Results First Posted: September 18, 2020
Last Update Posted: September 18, 2020
Last Verified: February 2020
Keywords provided by Pauline Cho, The Hong Kong Polytechnic University:
myopia control
orthokeratology
Additional relevant MeSH terms:
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Disease Progression
Disease Attributes
Pathologic Processes