There has been large acceptance that EMDR is an efficacious tool for addressing PTSD.  However, the actual mechansim and key elements that produce change are not as well understood.  Even though the EM in EMDR stands for “eye movement,” there are alternative modalities (e.g. auditory or tactile stimuli) that also seem to be beneficial.  In fact, many studies conclude that the eye movements may not actually be a salient component.  The following is an abstract from a paper that re-examines these studies and presents a cogent argument that eye movements do, in fact play an important role after all:

http://www.sciencedirect.com/science/article/pii/S0005791612001000