Clinical trial NCT03881358: Orthokeratology for High Myopia (OHM) Study
Official title: Orthokeratology for High Myopia (OHM) Study
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Myopia
High Myopia
Keywords: Myopia control
Orthokeratology
Children
Lead sponsor: The Hong Kong Polytechnic University
Sponsor class: OTHER
Collaborators: name: Queensland University of Technology
name: Aston University
First posted: 2019-03-19
Enrollment: 66
Sex: ALL
Minimum age (years): 7
Maximum age (years): 13
Standard ages: CHILD
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: This project aims to investigate/examine high myopic subjects on full correction ortho-k (using Topaz ortho-k lenses for high myopia) compared to subjects undergoing partial reduction ortho-k and their relationship with myopia and myopic progression.

Detailed description: For many years, commercially-available ortho-k lenses aim to reduce low - moderate myopia. Attempts to use these lenses for reduction of high myopia have been shown to give rise to complications such as corneal staining and lens decentration. Thus, practitioners may choose a more conservative way for high myopic children, that is, offering partial reduction ortho-k. Partial reduction ortho-k is target for 4.00-5.00D reduction and the residual refractive errors will be corrected with single vision spectacles to allow good visual acuity in the daytime. Partial reduction ortho-k has been shown to slow axial elongation in high myopic children, however, the main disadvantage is that the children have to wear spectacles in the daytime to correct residual refraction.

Euclid has recently designed a new lens, Euclid's Topaz, for high myopic children. It is currently commercially available to correct myopia for up to 10 D. However, evidence of its effectiveness for visual correction and slowing AL growth is lacking. While numerous studies have shown that orthokeratology is an effective clinical treatment to slow axial eye growth in children, the exact mechanism underlying this reduction in myopia progression associated with orthokeratology remains unclear.

Eligibility criteria: Inclusion Criteria:

* Myopia: at least 5.00D in one eye or in both eyes
* Astigmatism: ≤1.50D; with-the-rule astigmatism (axes 180 ± 30) ≤1.25D; astigmatism of other axes ≤0.50D in both eyes
* Anisometropia: not be more than 1.00D in the former and not more than 2.00D in the latter.
* Best-corrected Monocular Snellen visual acuity 6/7.5 or better

Exclusion Criteria:

* Strabismus at distance or near
* Previous experience in contact lens wear or myopia control treatment (e.g. refractive therapy or progressive spectacles)
* Contraindication for contact lens wear and orthokeratology (e.g. limbus to limbus corneal cylinder and dislocated corneal apex)
* Previous history of ocular surgery, trauma, or chronic ocular disease
* Concurrent use of medications that may affect tear quality or contact lens wear
* Systemic or ocular conditions that may affect tear quality or contact lens wear (e.g allergy and concurrent medication) or that may affect refractive development (e.g Down syndrome, ptosis)
* Poor compliance to tests (e.g poor fixation in noncontact tonometry or intolerance of lens wear)
* Not willing to comply with the allocated treatment, use and care of lenses and follow-up schedule

Primary outcomes:
measure: Change in axial length elongation over 24 months.
timeFrame: 2 years
Secondary outcomes:
measure: First fit success rate of a newly designed ortho-k lens for high myopic children
timeFrame: 1 month
measure: Quality of life (questionnaire)
timeFrame: 3 months
measure: Ocular aberration
timeFrame: 2 years
Other outcomes:
Locations:
city: Kowloon
country: Hong Kong
facility: School of Optometry, The Hong Kong Polytechnic University
Study officials:
affiliation: The Hong Kong Polytechnic University
name: Pauline Cho, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Lam CS, Goldschmidt E, Edwards MH. Prevalence of myopia in local and international schools in Hong Kong. Optom Vis Sci. 2004 May;81(5):317-22. doi: 10.1097/01.opx.0000134905.98403.18.
citation: Walline JJ, Lindsley K, Vedula SS, Cotter SA, Mutti DO, Twelker JD. Interventions to slow progression of myopia in children. Cochrane Database Syst Rev. 2011 Dec 7;(12):CD004916. doi: 10.1002/14651858.CD004916.pub3.
citation: Kakita T, Hiraoka T, Oshika T. Influence of overnight orthokeratology on axial elongation in childhood myopia. Invest Ophthalmol Vis Sci. 2011 Apr 6;52(5):2170-4. doi: 10.1167/iovs.10-5485.
citation: 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.
citation: Swarbrick HA. Orthokeratology review and update. Clin Exp Optom. 2006 May;89(3):124-43. doi: 10.1111/j.1444-0938.2006.00044.x.
citation: Walline JJ, Jones LA, Sinnott LT. Corneal reshaping and myopia progression. Br J Ophthalmol. 2009 Sep;93(9):1181-5. doi: 10.1136/bjo.2008.151365. Epub 2009 May 4.
citation: Charm J, Cho P. High myopia-partial reduction orthokeratology (HM-PRO): study design. Cont Lens Anterior Eye. 2013 Aug;36(4):164-70. doi: 10.1016/j.clae.2013.02.012. Epub 2013 Mar 18.
citation: Cho P, Cheung SW, Edwards MH. Practice of orthokeratology by a group of contact lens practitioners in Hong Kong. Part 2: orthokeratology lenses. Clin Exp Optom. 2003 Jan;86(1):42-6. doi: 10.1111/j.1444-0938.2003.tb03056.x.
citation: Lee TT, Cho P. Relative peripheral refraction in children: twelve-month changes in eyes with different ametropias. Ophthalmic Physiol Opt. 2013 May;33(3):283-93. doi: 10.1111/opo.12057.
citation: Atchison DA, Li SM, Li H, Li SY, Liu LR, Kang MT, Meng B, Sun YY, Zhan SY, Mitchell P, Wang N. Relative Peripheral Hyperopia Does Not Predict Development and Progression of Myopia in Children. Invest Ophthalmol Vis Sci. 2015 Sep 1;56(10):6162-70. doi: 10.1167/iovs.15-17200.
citation: Hiraoka T, Matsumoto Y, Okamoto F, Yamaguchi T, Hirohara Y, Mihashi T, Oshika T. Corneal higher-order aberrations induced by overnight orthokeratology. Am J Ophthalmol. 2005 Mar;139(3):429-36. doi: 10.1016/j.ajo.2004.10.006.
citation: Gonzalez-Meijome JM, Villa-Collar C, Queiros A, Jorge J, Parafita MA. Pilot study on the influence of corneal biomechanical properties over the short term in response to corneal refractive therapy for myopia. Cornea. 2008 May;27(4):421-6. doi: 10.1097/ICO.0b013e318164e49d.