If it is a retained eye cap, getting some moisture into the snakes skin is going to help quite a bit.
Since the eyes/eyecaps are on the top of the head soaking is only partially effective.
When I have snakes with retained eyecaps, I soak them for 20 minutes then put them in a wet snake bag and put the bag back into the cage and leave the snake in it overnight. Not only does this keep the skin moist, as the snake crawls around in the bag, they pretty much have to rub the eyecap on the inside of the bag.
This is the best way (I have found) to get of a retained eye cap with the lease amount of trauma to the snake.
Be sure to keep an eye on the snake, as prolonged exposure to wet conditions can cause scale rot.