None listed
Conditions
Brief summary
Orthokeratology (OK) lenses are rigid contact lenses that are designed to be worn during sleep. Their purpose is to reshape the front surface of the eye (cornea) in order to temporarily correct short-sightedness, also known as myopia. Although their primary aim is to correct myopia and provide clear unaided vision during the day, studies have shown that they also have an effect on slowing or stopping the progression of short-sightedness in children, termed myopia control. Currently lenses are fit on the eye by optometrists by fitting the lens on the corneal topographic map centred over the vertex normal. However, anecdotal reports suggest improved clinical outcomes are achieved when lenses are fit based on the topographical maps centred over the entrance pupil centre rather than vertex normal. The aim of this project is to compare the clinical outcomes of lenses that were designed based on the entrance pupil centre after 7 nights of overnight wear. We will investigate visual acuity, contrast sensitivity as well as optical aberrations. Our intent is to determine how these measurements can guide best clinical practice in fitting OK lenses.
Interventions
Description of intervention: Paragon CRT lenses (CooperVision Specialty EyeCare, Arizona, USA) in HDS100 material are used in this study. This is one of the most common materials used for conventional orthokeratology in Australia and abroad.
The lenses will be fitted to the entrance pupil by basing the lens fitting on topography measurements based on the default map centre. This will differ from the ‘no treatment’ condition where the fitting will be based on topography measurements obtained at t
Description of intervention: Paragon CRT lenses (CooperVision Specialty EyeCare, Arizona, USA) in HDS100 material are used in this study. This is one of the most common materials used for conventional orthokeratology in Australia and abroad. The lenses will be fitted to the entrance pupil by basing the lens fitting on topography measurements based on the default map centre. This will differ from the ‘no treatment’ condition where the fitting will be based on topography measurements obtained at the alternative reference centre. Both eyes will receive the same type of lens at the same time and participants will receive both intervention and control treatments. There will be a minimum 1 week period of no overnight lens wear during sleep between the wear of the study lens and the lens fit to vertex normal. Exposure: Study lenses are worn overnight during sleep (for minimum of 7-8 hours) over a period of 14 nights with each fitting method with no need for daytime lens wear. Delivery: The research team will initially insert the lens on the subject's eye at the School of Optometry and Vision Science, UNSW, Sydney. Research participants will then be taught one-on-one face-to-face how to insert, remove, clean and maintain orthokeratology lenses so that subjects can safely wear contact lenses during the trial period. Adherence to the study protocol will be ensured by the investigation team advising participants to complete an "Ortho-K Wear Time Journal” to record their OK lens insertion and removal times as well as sleep and waking up times.
Sponsors
University of New South Wales
Study design
Allocation
Randomised controlled trial
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver)
Eligibility
Sex/Gender
All
Age
18 Years to 40 Years
Healthy volunteers
No
Inclusion criteria
• Males and females between 18 and 40 years of age • Good ocular and general health • Refractive error -0.75 to -5.00D, corneal toricity (astigmatism) <1.50D • Anisometropia (spectacle difference between the two eyes) <0.75D • Individuals with a history of wearing rigid lenses (including orthokeratology) for a short-term (<=3months) ) and have discontinued wearing them for one month
Exclusion criteria
*Any current rigid gas permeable (including orthokeratology) lens wearers *Previous long-term (>3 months) rigid (including orthokeratology) lens wearers *Soft contact lens wear in the past week *Contraindications to rigid lens wear, including orthokeratology lens wearers • Participants having eye turns or lazy eye.
Outcome results
None listed