Craig, this sounds like Panophthalmitis. Fluid builds up under the spectacle of one eye. In its early stages it looks like the "opaque" stage of shedding except that it only occurs in one eye. If left too long it will swell up and usually the spectacle and the eye need to be removed. In its early stages an experienced vet can usually drain out the fluid and the eye is saved. This problem can often occur after the snake has had canker. I suggest you contact the person you got it off and see if it did have canker before you aquired it, and then discuss this problem with a vet. Perhaps even check inside the snakes mouth yourself to see if it does have a minor case of canker which hasnt made itself obvious yet.