None listed
Conditions
Brief summary
Excessive near work is considered to play a role in the development of refractive errors of the eye, especially myopia (also known as short-sightedness). Studies have shown that myopia onset is associated with the education. Our modern education commonly involves reading, writing, arithmetic (problem solving etc). During near work, the pupil (aperture that allows light into the eye) normally constricts (reduces in size) and in addition, the lens inside the eye (crystalline lens) changes shape to increase in power (accommodation). These changes allow the image to focus on the retina (photosensitive layer responsible for sending signals from eye to brain). Although it is commonly considered that pupil constricts (reduces in size) while doing near work, surprisingly, performing a cognitive task at near (solving mathematical problems) dilates the pupil. In a previous study conducted as part of our research, we have demonstrated that whilst doing near tasks, the accommodative system is engaged for both reading and cognitive tasks but not for gratings. In comparison, the pupil is constricted for reading, dilated for cognitive tasks, and remains unaltered for grating tasks. A smaller pupil will improve the depth of field and improve resolution whereas a larger pupil is likely to decrease retinal image quality due to increased aberrations. This in turn may play a role in development of myopia. Optical correction such as myopia control contact lenses and spectacle lenses, which were specifically designed with desired power profiles to reduce the optical defocus and enhance the retinal image quality were found effective in slowing myopia. It is important to determine if the pupillary and accommodative responses are altered with such treatment modalities. Other than optical correction, it has been thought that exposure of the eye to short wavelength light (blue light 440nm – 480nm) may influence myopia progression. Therefore, it is of interest to determine the accommodative and pupillary responses of the eye with habitual and myopia control strategies under normal light and blue light.
Interventions
A commercially available, dynamic autorefractor (Grand Seiko WAM 5500) will be used to measure accommodation and pupillary responses. Participants will be seated in front of this instrument with their chin and forehead comfortably rested. Participants will be asked to look at the computer display placed at 50cms. Text in English language and mathematical problems will be presented on the computer screen. Participants will be asked to read the text material and calculate the solution for the math
A commercially available, dynamic autorefractor (Grand Seiko WAM 5500) will be used to measure accommodation and pupillary responses. Participants will be seated in front of this instrument with their chin and forehead comfortably rested. Participants will be asked to look at the computer display placed at 50cms. Text in English language and mathematical problems will be presented on the computer screen. Participants will be asked to read the text material and calculate the solution for the mathematical problems. These tasks will be performed under the white and blue light illumination. Once participant is seated comfortably, the examiner aligns the instrument and records the data by pressing the start button of the instrument. Accommodation and pupillary responses will be recorded using auto refractor. Measurements would be performed under normal binocular viewing and participants can blink normally while the measurement is in progress and regular breaks will be provided between the measurements. All the measurements using autorefractor will be performed inserting a soft contact lens which is equivalent to the participants habitual refractive correction to get the accurate measurements from the instrument. Participants will be fitted with a soft contact lens for the duration of the study. A clean, sterile lens will be removed from the package and inserted on the eye. The lens will be inserted by research student (who has experience in fitting the contact lens) under the supervision of registered optometrist and participants will be required to wear the contact lens for approximately 45 minutes (for each type of lens). Once the study procedures are completed, the contact lens will be removed and discarded. Participants have to attend three visits and the measurements will be done using commercially available daily disposable soft contact lenses, MiSight contact lenses from CooperVision Inc, and Miyo Smart spectacle lenses from Hoya corporation. Each session would take approximately 45 minutes only. Acuvue moist lenses are single vision contact lenses whereas MiSight contact lenses and Miyo Smart lenses are multifocal contact lenses and spectacles for myopia control from CooperVision Inc and Hoya corporation respectively. Wash out period between the sessions would be 24 hours. Study Location: Brien Holden Vision Institute, University of New South Wales
Sponsors
Geetha Sravani
Eligibility
Sex/Gender
All
Age
18 Years to 35 Years
Healthy volunteers
No
Inclusion criteria
• Presence of myopia; • Age between 18 - 35 years. • No ocular disease or history of ocular injury. • Normal systemic health and not on any medications which may influence ocular health • No prior refractive surgery; • No ocular or systemic medications that may affect the pupillary response; • No history of amblyopia (lazy eye) or strabismus (eye not looking straight) • Able to read and comprehend English • Willing to wear contact lens during the study: can be an experienced soft contact lens wearer or no prior contact lens wear experience.
Exclusion criteria
• Eye diseases such as oculomotor nerve palsies, glaucoma, amblyopia and binocular vision anomalies like nystagmus, strabismus which may affect the accommodation or cognition. • Aged 36 years or older and younger than 18 years • Presence of astigmatism >1.00 DC • History of any systemic diseases including diabetes, hypertension, cardiac problems • History of any refractive or ocular surgeries • History of any other ocular pathology • Intra ocular pressure >/= 21 mm of Hg (which would be determined by research team while screening). • Ocular hypertension or glaucoma in either eye
Outcome results
None listed