None listed
Conditions
Brief summary
Myopia or nearsightedness is characterized by elongation of an eye length that is greater than normal. The prevalence of the condition is high (>90% of young adult Taiwanese are myopic) in many parts of the world and rising elsewhere. Higher levels of myopia lead to several sight threating complications such as retinal detachment, glaucoma and cataract. Myopia is associated with a significant economic and health burden. There exist treatment strategies that can slow the progression of myopia in children. Evidence suggests that ocular growth and refractive development is sensitive to visual signals including optical defocus. Imposing hyperopic defocus (i.e., have the image plane fall behind retina) can lead to ocular elongation whereas myopic defocus was found to slow ocular elongation in chicks, guinea pigs, and monkeys. Spectacle and contact lens designs incorporating segments or sections of the lens devoted to myopic defocus were seen to significantly reduce myopia progression in children. Interestingly, observations indicate that wearing range of multifocal lens designs may slow myopia progression compared to wear of full field negative lenses. Thus, there is a need to better understand the response of a human eye to multifocal lenses to determine if there are differences in responses to different types of multifocal lenses. PRIMARY AIM: To investigate changes if any in axial length (central and peripheral) of myopic eyes to short term (60 mins) wear of multifocal spectacle lenses. Secondary Aims: To investigate changes if any in, - refractive error (central and peripheral) - choroidal thickness - contrast sensitivity function Potential significance of study: The findings of the study will help understand the ocular response to different types of optical blur and may play a role in development and/or refinement of optical strategies to slow myopia.
Interventions
This will be a prospective, randomized, non-dispensing, short term wear (60 minutes) clinical trial. 20 healthy young adults with low to moderate myopia (-0.75D to -5.0D) will be enrolled. Participants will be asked to wear a 5 different types of multifocal spectacle lenses and one single vision spectacle lens over 6 days with a minimum of 24 hour of washout period between each lens wear. They will be asked to wear a spectacle frame fitted with a plano powered spectacle lens in one of the two
This will be a prospective, randomized, non-dispensing, short term wear (60 minutes) clinical trial. 20 healthy young adults with low to moderate myopia (-0.75D to -5.0D) will be enrolled. Participants will be asked to wear a 5 different types of multifocal spectacle lenses and one single vision spectacle lens over 6 days with a minimum of 24 hour of washout period between each lens wear. They will be asked to wear a spectacle frame fitted with a plano powered spectacle lens in one of the two eye frames and one of the randomly assigned multifocal spectacle lens in the other eye frame for 60 mins. Measurements of refractive error, axial length, choroidal thickness and contrast sensitivity will be measured before and after lens wear. Lens descriptions: Lens 1 is a single vision spectacle lens (control) Lens 2 is a commercially available multifocal ophthalmic spectacle lens (control). Lens 3 to 6 are prototype spectacle lenses, comprise of central zone for refractive error correction and a peripheral zone area comprising a refractive power that varies from central zone up to +/- 5.0D. Prototypes 3 and 4 will have central zone diameter of up to 9 mm whereas prototypes 5 and 6 will have central zone diameter of up to 5 mm. This study will be conducted at Brien Holden Vision Institute Clinic and will be conducted and managed by student researcher with supervision by BHVI employed registered research optometrist and the study investigators. Student researcher is an optometrist by background with experience in study procedures including fitting of contact lenses and spectacles. He has also completed Good Clinical Practice training. Brien Holden Vision Institute has clinical facilities to conduct the study and access to relevant study population. Each participant will have 6 visits including Screening/Baseline visit. (Screening/Baseline will take anywhere between 2-2.5 hour and each of the follow up visits will take approximately 1.5 hour). There will be a wash out period of a minimum of 24 hours between visits. It is a non-dispensing, short term trial where participants will wear the lenses for 60 mins and stay in the clinic for the entire duration. Therefore, adherence to the strategy is monitored and recorded by the student researcher.
Sponsors
Brien Holden Vision Institute
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
• Non-cycloplegic spherical equivalent refractive error ranging from -0.75D to –5.00D • Best corrected visual acuity of 20/30 or better in both eyes • Normal ocular health (No ocular disease) • No history of ocular surgery; • No manifest squint or intermittent tropias; • Astigmatism less than 1.50 D; • Anisometropia of not more than 1.00 D; • Absence of any ocular disease that might influence the trial outcomes- for example corneal or retinal disease, cataract and ptosis. • Normal general health. • No current use of ocular or systemic medications excepting use of lubricating or anti-allergic eye drops
Exclusion criteria
• Use of rigid contact lens wear • Any prior myopia control treatment • Not willing to give consent; and • Not willing to present for the required visit schedule
Outcome results
None listed