Toric Orthokeratology - Slowing Eye Elongation

Myopia Clinical Trial

— TO-SEE  

Official title:

Toric Orthokeratology for Slowing Eye Elongation in Astigmatic Children

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00978692
• Other study ID #: H-ZG30
• Status: Completed
• Phase: N/A
• First received: September 16, 2009
• Last updated: February 18, 2016
• Start date: May 2008
• Est. completion date: December 2012

Study information

• Verified date: February 2016
• Source: The Hong Kong Polytechnic University
• Contact: n/a
• Is FDA regulated: No
• Health authority: Hong Kong: Ethics Committee
• Study type: Interventional

Clinical Trial Summary

The aims of this study are to investigate the effects of ortho-k for astigmatic and myopic reduction and myopic control in children, and the long term effects on corneal curvatures and biomechanics.

Description:

Ortho-k has been shown to be effective in correcting low myopia but relatively ineffective for astigmatism, using spherical reverse geometry lens designs. Toric ortho-k lenses have been introduced in recent years but the efficacy for astigmatic reduction and for myopic control in children have not been confirmed. The mechanism of myopic reduction in ortho-k cannot be fully explained by changes to the anterior corneal curvatures. It is therefore possible that other corneal parameters such as posterior corneal curvature and corneal biomechanics may contribute to the mechanism.

The current study aims at investigating the efficacy of toric ortho-k lenses for correcting myopic astigmatism and for retarding myopic progression in children compared to children wearing single-vision spectacles. Long term changes to other corneal parameters such as posterior cornea curvatures, topographical corneal thickness, corneal hysteresis, corneal resistance factor, with and without ortho-k lens wear will also be investigated.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 80
• Est. completion date: December 2012
• Est. primary completion date: July 2012
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 6 Years to 12 Years

Eligibility

Inclusion Criteria:

• Myopia (refractive sphere): more than -0.50DS to -5.00DS

• Astigmatism: with-the-rule astigmatism more than -1.25DC

• Anisometropia: = 1.50D in both refractive sphere

• Best corrected monocular visual acuity: equal to or better than 0.10 in logMAR scale in both eyes

• Availability for follow-up for at least 2 years

Exclusion Criteria:

• Strabismus at distance or near

• Contraindication for contact lens wear and orthokeratology (e.g. limbus to limbus corneal cylinder and dislocated corneal apex

• Prior experience with the use of rigid lenses (including orthokeratology)

• Prior experience with myopia control treatment (e.g. refractive therapy or progressive spectacles)

• Systemic or ocular conditions which may affect contact lens wear (e.g. allergy and medication)

• Systemic or ocular conditions which may affect refractive development (e.g. Down syndrome, ptosis)

Study Design

Allocation: Non-Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Investigator), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Astigmatism
• Myopia

Intervention

Device:
• Toric Orthokeratology lenses
Children wearing toric orthokeratology at night for correcting astigmatism and myopia will be the study group
• Single-vision spectacles
Children wearing single-vision spectacles in the daytime for correcting the refractive errors will serve as the control group

Locations

Country	Name	City	State
China	School of Optometry, The Hong KOng Polytechnic University	Hong Kong SAR

Sponsors (2)

Lead Sponsor	Collaborator
The Hong Kong Polytechnic University	Menicon Co., Ltd.

Country where clinical trial is conducted

China, 

References & Publications (3)

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. — View Citation

Chen C, Cho P. Toric orthokeratology for high myopic and astigmatic subjects for myopic control. Clin Exp Optom. 2012 Jan;95(1):103-8. doi: 10.1111/j.1444-0938.2011.00616.x. Epub 2011 Sep 5. — View Citation

Chen CC, Cheung SW, Cho P. Toric orthokeratology for highly astigmatic children. Optom Vis Sci. 2012 Jun;89(6):849-55. doi: 10.1097/OPX.0b013e318257c20f. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	To determine the eyeball elongation in children wearing ortho-k lenses		Before lens wear, 6, 12,18, 24 months after lens wear	No
Secondary	To determine the posterior corneal curvatures, topographic corneal thickness, corneal volume, corneal hysteresis and corneal resistance factor in a group of children and compare these parameters with the ortho-k children		Before lens wear, 6, 12,18, 24 months after lens wear	No
Secondary	To investigative the efficacy of toric orthokeratology for correcting astigmatism and myopia		Before lens wear, 6, 12,18, 24 months after lens wear	No