There is a theory that memories are stored in the brain through our sensory channels, most notably visual, auditory, and kinesthetic. There is a correlation between these sensory accessing modalities, and the direction that eyes move. For instance, when we are attempting to remember something that has been stored in our visual channel, we tend to look up. When w are remembering something we heard, we tend to look to the side, in the direction of our ears. While remembering something we felt, we tend to look downward.
When disturbing memories are being processed, moving the eyes from right to left while looking up, looking straight ahead, and looking downward can dislodge the intensity of that event. Likewise, when new feelings and perspectives are accessed, eye movement therapy may help to anchor them.
In my practice, eye movement is applied only briefly in context with other techniques as needed.