Watch your children with CVI move to get into a chair. So often I see this done tactilely. They turn and backup slowly until they feel the chair seat against the back of their legs. I believe this is due to the difficulties judging distance, the visual complexity of this task and visual motor difficulties.
I have had great luck working with the PT and OT to help children understand where the chair is in space and how to move their body into the seated position.
Here is one example. Just by placing red tape on one arm of the modified toilet we could teach the child to find the highlighted armrest of the chair, cross midline, hold the red highlighted area to stabilize their body and to turn to sit. As they improved their skills, we were able to reduce the size of the color highlighting and finally remove it. This provided safe and more independent toileting.