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

NCT02643875 | Completed Results

• 1 other identifier: HSEARS20151002004
• Study Type: interventional
• Target: 36
• Locations: 1 country
• Sites: 1

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.

Conditions

Myopic Progression

Keywords

myopia control; orthokeratology

Outcome Measures

Primary Outcomes (1)

• Changes in Spherical Equivalent Refraction

  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.

  baseline and one month

Secondary Outcomes (2)

• Changes in Subfoveal Choroidal Thickness

  baseline and one month

• Changes in Higher Order Aberrations

  baseline and one month

Study Arms (2)

Ortho-k lens with normal compression factor

SHAM COMPARATOR

The eye wears ortho-k lens with normal compression factor to achieve plano (+/- 0.25D) correction.

Device: Orthokeratology

Ortho-k lenses with increased compression factor

ACTIVE COMPARATOR

The eye wears ortho-k lenses with increased compression factor to achieve 1 diopter (+/- 0.25D) over correction.

Device: Orthokeratology

Interventions

Orthokeratology DEVICE

It is a kind of rigid permeable lens.

Ortho-k lens with normal compression factor; Ortho-k lenses with increased compression factor

Eligibility Criteria

• Age: 6 Years - 10 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• to 10 years old
• Myopia: between 0.50 D and 4.00 D in both eyes
• 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
• Anisometropia: ≤ 1.50 D
• Symmetrical corneal topography with corneal toricity \<2.00 D in both eyes
• Agree for randomization

You may not qualify if:

• Contraindications for orthokeratology wear (e.g. limbus-to-limbus corneal cylinder and dislocated corneal apex)
• Any type of strabismus or amblyopia
• Myopic treatment (e.g. refractive surgery and progressive lens wear for myopic control) before and during the study period
• Rigid contact lenses (including orthokeratology lenses) experience
• Systemic condition which might affect refractive development (for example, Down syndrome, Marfan's syndrome)
• Ocular conditions which might affect the refractive error (for example, cataract, ptosis)
• Poor compliance for lens wear or follow-up

Sponsors & Collaborators

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

Study Sites (1)

The Hong Kong Polytechnic University

Hong Kong, China

Location

Related Publications (7)

• 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. doi: 10.1080/02713680590907256.

  PMID: 15875367 BACKGROUND

• 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.

  PMID: 22969068 BACKGROUND

• 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.

  PMID: 24003088 BACKGROUND

• 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.

  PMID: 18426426 BACKGROUND

• Wan K, Lau JK, Cheung SW, Cho P. Refractive and corneal responses of young myopic children to short-term orthokeratology treatment with different compression factors. Cont Lens Anterior Eye. 2020 Feb;43(1):65-72. doi: 10.1016/j.clae.2019.10.134. Epub 2019 Nov 6.

  PMID: 31704093 RESULT

• Lau JK, Vincent SJ, Cheung SW, Cho P. The influence of orthokeratology compression factor on ocular higher-order aberrations. Clin Exp Optom. 2020 Jan;103(1):123-128. doi: 10.1111/cxo.12933. Epub 2019 Jul 1.

  PMID: 31264269 RESULT

• Lau JK, Wan K, Cheung SW, Vincent SJ, Cho P. Weekly Changes in Axial Length and Choroidal Thickness in Children During and Following Orthokeratology Treatment With Different Compression Factors. Transl Vis Sci Technol. 2019 Jul 23;8(4):9. doi: 10.1167/tvst.8.4.9. eCollection 2019 Jul.

  PMID: 31360614 RESULT

Results Point of Contact

• Title: Prof Pauline Cho
• Organization: The Hong Kong Polytechnic University

sopaulin@polyu.edu.hk

(852) 2766-6100

Study Officials

• Pauline Cho, PhD

  The Hong Kong Polytechnic University

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: December 28, 2015
• First Posted: December 31, 2015
• Study Start: February 26, 2016
• Primary Completion: November 18, 2016
• Study Completion: November 18, 2016
• Last Updated: September 18, 2020
• Results First Posted: September 18, 2020

Record last verified: 2020-02

Locations

CN (1)