The ions present in liquid crystal devices modulate the applied electric field and lead to deterioration of the expected good optical response. In addition to the flicker and ghost images, a boundary image-retention effect is also possible. It occurs near the edges of a stressed pixel. We have attributed this effect to ions moving in the lateral direction, perpendicular to the applied electric field. This hypothesis has been proven using a combination of electrical and optical measurements and the measurements have been explained using the new model of lateral ion transport. The physical cause of this phenomenon is still not clear and is a subject of further study.