In the fifth Palm Change (li) the eyes are trained not to respond to, or get drawn off when arms come in and out of the field of vision. This is done by circling the arms in the coronal plane, while turning and walking. It is also used for training us to not blink when bursts of air or hands come suddenly toward the eyes.
In the sixth palm change (kan) the eyes do the same thing they do in the third palm change, but instead of spinning the body, the head looks spontaneously form side to side, creating a similar blur or whirl effect while doing the palm change.
Again, it is easy to imagine these uses of the eyes becoming different types of possession. The fourth, taken to extremes is what people who are manic look like after not sleeping for a few days.
The eyes of the fifth are important for any type of fighting, but would be dangerous walking through brush because we need to close our eyes quickly if a branch is snapping toward them. I know of an old Gongfu master who worked bank security and kept a bit of metal-filings dust in his pocket to throw in peoples eyes if necessary. Better hope your blink reflex is operating if that happens. Taken to a possessed extreme, these are the bug eyes we sometimes see on crazy people.
The eyes of the sixth can be many things, among them an Exorcist head spinning type of effect, also seen in African and Chinese possessions.
If it is not obvious already, there is some danger in trying these yourself. The danger is minor as long as you:
1. Are relaxed, the eyes should never ever feel like they are doing work.
2. Understand that you are learning what not to do.
3. Are comfortable trying to be just below average.
4. Know in your heart that cultivating weakness is O.K. because we humans are strong enough already.