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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
20
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').
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').
Chester F. Carlson Center for Imaging Science
Rochester, New York, United States
RECRUITINGGain and phase of ocular accommodation
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.
Time frame: Each measurement takes 10 seconds. In the experiment, the investigators will take measurements over the course of approximately 1 hour.
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