title: Head orientation and meridional variations in acuity.
mesh_terms: D003623:Dark Adaptation; D006257:Head; D006801:Humans; D009949:Orientation; D011187:Posture; D012160:Retina / Q000502:physiology*; D013028:Space Perception; D013997:Time Factors; D014792:Visual Acuity; D014794:Visual Fields