Toric Orthokeratology - Slowing Eye Elongation

The Hong Kong Polytechnic University80 enrolled

Overview

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.

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 Type

INTERVENTIONAL

Allocation

NON_RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Enrollment

Conditions

Myopia Astigmatism

Interventions

Toric Orthokeratology lensesDEVICE

Children wearing toric orthokeratology at night for correcting astigmatism and myopia will be the study group

Single-vision spectaclesDEVICE

Children wearing single-vision spectacles in the daytime for correcting the refractive errors will serve as the control group

Eligibility

Sex: ALLMin age: 6 YearsMax age: 12 YearsHealthy volunteers:

Medical Language ↔ Plain English

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)

Locations (1)

School of Optometry, The Hong KOng Polytechnic University

Hong Kong SAR, China

Outcomes

Primary Outcomes

To determine the eyeball elongation in children wearing ortho-k lenses

Time frame: Before lens wear, 6, 12,18, 24 months after lens wear

Secondary Outcomes

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

Time frame: Before lens wear, 6, 12,18, 24 months after lens wear

To investigative the efficacy of toric orthokeratology for correcting astigmatism and myopia

Time frame: Before lens wear, 6, 12,18, 24 months after lens wear

Data from ClinicalTrials.gov

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