There is no way I would put a drop of cayenne in an eye wash. I don't think a wash will stop twitching, because that is a function of nerves and muscles. I would take a break from cleansing for a couple of days and see if the twitching stops.
If you purge your system too quickly it will do more harm than good. Back off and give body body time to recuperate. If the twitching stops, crank it back up to 20+ drops of sski in water twice daily. If it doesn't, I would take some herbs that have a reputation for repairing nerve damage and see if that helps.
If you must wash your eyes, they make some MSM eye drops. Try that.