Eye movement desensitization and reprocessing (EMDR) is a treatment for PTSD. In EMDR, a patient brings to mind emotionally unpleasant images and beliefs about themselves related to their traumatic event. With these thoughts and images in mind, patients are asked to also pay attention to an outside stimulus, such as eye movements or finger tappings guided by the therapist.
For example, in a session of EMDR, a patient may be asked to bring attention to an unpleasant image in their mind, as well as negative beliefs and body sensations associated with the traumatic event. At the same time, the patient is asked to move his eyes side-to-side for several seconds. Afterward, the patient will deep breathe and discuss what was brought up during the exercise. Whatever was brought up can then be used for another exposure exercise. This cycle continues until patient's distress has reduced.
Proponents of EMDR suggest that it works by building new connections between a patient's traumatic memories and adaptive information (for example, positive beliefs) within other areas of the memory, bringing about a reduction in PTSD symptoms. Although there is research to support EMDR as a treatment for PTSD, there is some criticism that these studies were not all well-conducted and there is disagreement as to how it really works (i.e., it may operate in a similar way to exposure therapy).
You can read more about EMDR here.
Lilienfeld, S., Lynn, S., & Lohr, J. (2002). Science and Pseudoscience in Clinical Psychology. New York, NY: Guilford Press.
Lilienfeld, S. O. (Jan/Feb 1996). EMDR Treatment: Less Than Meets the Eye? Skeptical Inquirer.
Maxfield, L. (2002). Eye movement desensitization and reprocessing int he treatment of posttraumatic stress disorder. In C.R. Figley (Ed.), Brief Treatments for the Traumatized (pp. 148-170). Westport, CT: Greenwood Press.