Toric Orthokeratology - Slowing Eye Elongation

Not Applicable

Completed

• Conditions: Myopia; Astigmatism
• Interventions: Device: Single-vision spectacles; Device: Toric Orthokeratology lenses

• Registration Number: NCT00978692
• Lead Sponsor: The Hong Kong Polytechnic University

Brief 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.

Detailed 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.

Study Timeline

• Study Start: 2008-05
• Study First Submitted: 2009-09-16
• Study First Submitted QC: 2009-09-16
• Study First Posted: 2009-09-17
• Primary Completion: 2012-07
• Study Completion: 2012-12
• Status Verified: 2016-02
• Last Update Submitted: 2016-02-18
• Last Update Posted: 2016-02-22

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 80

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

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Single-vision spectacles	Single-vision spectacles	Children wearing single-vision spectacles in the daytime for correcting the refractive error will be serve as control group
Toric orthokeratology lenses	Toric Orthokeratology lenses	Children wearing toric ortho-k lenses at night for correcting astigmatism and myopia will be the study group

Primary Outcome Measures

Name	Time	Method
To determine the eyeball elongation in children wearing ortho-k lenses	Before lens wear, 6, 12,18, 24 months after lens wear

Secondary Outcome Measures

Name	Time	Method
To investigative the efficacy of toric orthokeratology for correcting astigmatism and myopia	Before lens wear, 6, 12,18, 24 months after lens wear
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

Trial Locations

Locations (1)

School of Optometry, The Hong KOng Polytechnic University; 🇨🇳 Hong Kong SAR, China