title: Eye and head contribution to gaze at near through multifocals: the usable field of view.
abstract: Presbyopes show that for targets presented within a 28 degrees clear field of view, gaze is accomplished by head and eye movements with head movements making an average contribution of 24%. A clear field of view which incorporates the factor of segment width provides an underestimation because of the factor of head movements. By including the effect of head movements, a fixed segment width provides a much wider clear field of view which we term the usable field of view.
mesh_terms: D005133:Eye Movements; D005139:Eyeglasses; D005403:Fixation, Ocular; D006257:Head; D006801:Humans; D009068:Movement; D055095:Optics and Photonics; D011305:Presbyopia / Q000628:therapy*