Eye movements are a key factor in human vision. During steady state fixation where the visual attention is voluntarily centred on a fixation estimulous, the eye shows involuntary small movements that exhibit an erratic trajectory. This book describes fixational eye movements, their mathematical models, and the factors that affect fixation. Also explored, herein, is Congential Nystagmus, which is one of the diseases that affect binocular vision, reducing the visual quality of a subject, saccadic eye movements, eye movement patterns in hemispatial neglect and eye-gaze input systems used by people with severe disabilities.