Abstract
Purpose:
The aim of the current study was to determine changes in the contribution of the head in gaze shifts to peripheral visual targets, according to the properties of the stimuli and the requirements of the task. Furthermore, we aimed to determine whether eye-head coordination may adapt after one month of presbyopia correction by progressive ophthalmic lenses.
Methods:
Twenty-one subjects participated in this experiment (6 young adults aged between 18 and 30 and 15 presbyopes aged between 40 and 50 and wearing progressive lenses for the first time). We used a head-mounted IR tracker to record head rotations during head-unrestrained gaze shifts to stimuli displayed at 40° of eccentricity. In one task, subjects were instructed to look at the peripheral targets, composed of LEDs and letters. Letters could be displayed at 3 different sizes (2.5; 0.5; 0.15° of visual angle). In another task, participants were instructed to recognize the letters. Measurements were repeated 3 times, with 1 week between the first and the second sessions and 3 weeks between the second and third.
Results:
Results showed that, for the first session, amplitudes of head movements were significantly higher only when subjects had to recognize the smallest letters. This difference was not found anymore in the third session.
Conclusions:
The current study showed that eye-head coordination strategy changed when the properties of the task and/or the peripheral targets were modified. The recognition of small eccentric letters required a higher involvement of the head in gaze shift. After one month of adaptation to new progressive ophthalmic lenses, eye-head behaviors became homogenous in all conditions.
Keywords: 753 vision and action •
525 eye movements: saccades and pursuits •
653 presbyopia