Researchers used the Eyetrack Monitoring System (ETMS), an infrared, video-based system that has been used previously to compare head and eye movements during reading for different spectacle progressive addition lens designs (corrective lenses used in eyeglasses to correct presbyopia). The custom-designed, head-mounted video camera was used to capture the image of the left eye with the contact lenses in place on both eyes during binocular viewing. Lenses were marked with small, black dots to assess lens position. The ETMS captured lens rotational images immediately upon lens insertion, and it continuously collected them at 30 frames per second, until all testing was completed.
Four tasks involving saccades (quick, simultaneous movements of both
eyes in the same direction), chosen to mimic real-world situations, were
then assessed in the following order:
-- Settling Time - Participants were allowed to view the examination room
freely for 15 minutes, while the lens was settling on the eye.
-- Reading - Participants read a newspaper with wide text for 2 minutes.
-- Visual Search - Participants gazed centrally, and then were instructed
to identify a number embedded within the text of a newspaper, read the
specified paragraph, and then return to primary position. The
paragraphs were positioned randomly from the center of the field in
-- Large versional tasks - Participants were instructed to blink to the
sound of a metronome set at 40 beats per minute. At approximately 20-
second intervals, they were instructed t
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