The Safety and Effectiveness of Breath-O Lenses

Not Applicable

Completed

Brief Summary: In Hong Kong, approximately 80% of children are myopic by the end of childhood. There is intense interest currently in the potential role of peripheral defocus as a clinical treatment to slow myopia progression. One of the most successful treatments for myopia is orthokeratology. Currently, Breath-O correct lenses are new designed ready-made orthokeratology lenses. This study is to evaluate the safety of wearing this new orthokeratology lens and the effectiveness of clinical performance in young adult.

Detailed Description: Short-sightedness (myopia) is the most common refractive error in the world. In Hong Kong, approximately 80% of children are myopic by the end of childhood. Current treatment strategies to control (i.e. slow) myopia progression in children are primarily designed to harness the natural "emmetropization" process, in which visual feedback from retinal image clarity regulates the rate of eye growth. There is intense interest currently in the potential role of peripheral defocus as a clinical treatment to slow myopia progression, not least since this approach permits clear central vision. One of the most successful treatments for myopia is orthokeratology, which is a therapy of using custom-made rigid gas permeable contact lens. The special design of this contact lens can reshape the corneal profile to minimize the central refractive error while producing beneficial peripheral defocus. Currently, Breath-O correct lenses are new designed ready-made orthokeratology lenses which are made of new material with more elasticity as compared traditional lens material. This study is to evaluate the safety of wearing this new orthokeratology lens and the effectiveness of clinical performance in young adult.

Recruitment & Eligibility

Inclusion Criteria

Refractive error: Spherical: normally -1.00D to -4.00D (maximum up to -5.00D); Cylindrical: normally half of Sph (against-the-rule Astigmatism.: lower than -0.75D) (maximum up to -1.50D)
Best corrected Visual acuity: monocular ETDRS 0.0 or better
Ocular health: No ocular abnormality, no contra-indications for overnight orthokeratology lens wear, no refractive surgery
General health: No systemic diseases
Requirement: No history of orthokeratology lens wearing. Agree to participate in this study and willing to wear the orthokeratology lenses overnight in accordance with the instructions given and to come back for follow up within the study period

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Treatment	Breath-O-Correct Lens	Wearing the orthokeratology lenses for 3 months

Primary Outcome Measures

Name	Time	Method
Corneal Endothelial Health in Terms of Endothelial Cell Density	Baseline, 1st Month, 3rd Month	measured by specular microscope
Corneal Endothelial Health in Terms of Percentage of Variation in Cell Size	Baseline, 1st Month, 3rd Month	measured by specular microscope
Anterior Ocular Health in Terms of Limbal and Bulbar Redness	Baseline, 1st Month, 3rd Month	measured by OCULUS Keratograph® 5M and graded by JENVIS redness grading system It is a scale of 0 to 4, the higher the score, the more redness the ocular surface manifests
Corneal Biomechanics in Terms of Corneal Hysteresis and Resistance Factor	Baseline, 1st Month, 3rd Month	measured by ocular response analyser
Anterior Ocular Surface Evaluation in Terms of Non-invasive Keratography Break-up Time (NIKBUT)	Baseline, 1st Month, 3rd Month	measured by OCULUS Keratograph® 5M

Secondary Outcome Measures

Name	Time	Method
Best Corrected Visual Acuity in Terms of High and Low Contrast	Baseline, 1st Month and the 3rd Month	The best corrected visual acuity was measured in LogMAR (Snellen 20/20 vision = 0.00 in LogMAR ; each readable letter add -0.02 to the score, the smaller the number i.e. more negative, the better visual acuity)
Reduction of the Refractive Power After Wearing the Breath-O-correct Lens	Baseline, 1st Week, 1st Month, 3rd Month	Refractive errors were determined by subjective refraction for treatment group (Breath-O correct lens wearer), the outcome was represented as mean spherical equivalent refraction with unit in diopter (SER, = 1/2 Cylindrical power + spherical power)