Just to make sure, you can soak your snake in a plastic tub with holes with warm water for about 45 minutes, it helps the lymphatic liquid (the liquid is rich in enzymes that help with the shed) which is in between the old shed and the new shed, if you see that the color of the eye gets a little bit more opaque, then it means that liquid is inside and thus there is a retained eye cap.
If you see no difference, check in the water just in case in the meantime the eyecap hasn't fall off, you'll see it floating.
If there isn't any change, the it's probable that it's just the eye and no stuck skin.