Distance Viewing, Prolonged Near Viewing
Conditions
Keywords
Ocular accommodation, Physiological optics, Near vision
Brief summary
In this experiment, subjects will view a cross pattern on the screen and be asked to focus their eyes on it. The cross pattern will look like it is moving towards and away from the eye in a back-and-forth motion. As the subjects focus their eyes on the shapes, the investigators will measure the focus of their eyes using a device called a wavefront sensor. This device uses infrared light to measure the optical properties of the eye in real time. Our goal is to find out how well the eye focuses before and after viewing images on a screen up close (25cm). Since many people spend a lot of time looking at a computer screen while at work or at school, it is important to understand how this affects the eye's ability to focus.
Detailed description
In this experiment, subjects will view a Maltese cross pattern on a display through a Badal relay. Subjects will be instructed to accommodate to the pattern while a focus-adjustable lens optically moves the display closer and farther in depth as a sinusoidal function of time. As they do so, the investigators will measure the wavefronts of their eyes using a Shack-Hartmann wavefront sensor. The investigators will measure the gain and phase of the accommodative response of the subjects' eyes. Measurements will be made before and after sustained viewing of images on a computer screen 25cm away.
Interventions
OTHERNear viewing first
In a given session of the experiment (1.5 hours), participants do 2 sets of accommodation tasks. One task happens after viewing a screen for 20 minutes at 25cm, and the other task happens after looking at a distant object (10m) for 20 minutes. In one intervention, the session is structured such that the screen is viewed first ('near viewing first').
OTHERDistant viewing first
In a given session of the experiment (1.5 hours), participants do 2 sets of accommodation tasks. One task happens after viewing a screen for 20 minutes at 25cm, and the other task happens after looking at a distant object (10m) for 20 minutes. In one intervention, the session is structured such that the distant object is viewed first ('distant viewing first').
Sponsors
Rochester Institute of Technology
National Eye Institute (NEI)
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Between 18-35 years of age * Normal or corrected-to-normal (glasses/contact lenses) vision.
Exclusion criteria
* Vision worse than 20/20 while wearing glasses / contact lenses. * Fragile or loose teeth (participants need to bite a piece of dental clay to stabilize their heads so that measurements can be taken from their eyes) * Current pregnancy (experiment requires sitting down without moving for stretches of time) * Heart disease * Personal/familial history of epilepsy
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Gain and phase of ocular accommodation | Each measurement takes 10 seconds. In the experiment, the investigators will take measurements over the course of approximately 1 hour. | Ocular accommodation is the focusing response of the lens in the eye. When the stimulus viewed by the participant changes in distance, the eye automatically refocuses. The investigators measure this refocusing using a device called a wavefront sensor. The investigators are particularly interested in the gain of accommodation, which is the ratio of the amplitude of accommodation to the amplitude of sinusoidal changes in stimulus distance. The investigators are also interested in the phase of the accommodative response, which is related to the lag of the accommodative response. |
Countries
United States
Contacts
CONTACTBenjamin M Chin, Doctorate
PRINCIPAL_INVESTIGATORBenjamin M Chin, Doctorate
Rochester Institute of Technology
Outcome results
None listed