EMDR (Eye Movement Desensitization and Reprocessing) is a psychotherapy that enables people to heal from the symptoms and emotional distress that are the result of disturbing life experiences.
Repeated studies show that by using EMDR therapy people can quickly experience the benefits of psychotherapy that once took years to make a difference. It is widely assumed that severe emotional pain requires a long time to heal. EMDR therapy shows that the mind can in fact heal from psychological trauma much as the body recovers from physical trauma. EMDR therapy is an eight-phase treatment. Eye movements (or other bilateral stimulation) are used during one part of the session.
After the clinician has determined which memory to target first, he asks the client to hold different aspects of that event or thought in mind and to use his eyes to track the therapist’s hand as it moves back and forth across the client’s field of vision. As this happens, for reasons believed by a Harvard researcher to be connected with the biological mechanisms involved in Rapid Eye Movement (REM) sleep, internal associations arise and the clients begin to process the memory and disturbing feelings. In successful EMDR therapy, the meaning of painful events is transformed on an emotional level.
More information can be found here: https://www.emdr.com/what-is-emdr/