Have you been checked for sjogren's? That goes after the nerves and the eyes. I am borderline positive for it and have eye issues (some days worse than others). Sjogren's isn't really a diagnosis, it is just a syndrome that they haven't found a cause for- so still idiopathic really. I know that some people get much relief from anti-inflammatory eye drops though.
As far as I know sfn doesn't cause swelling. It is the disease process that causes the inflammation that is hurting the nerves, so what ever that is would be what is affecting your eyes. Unless maybe you just have conjunctivitis or allergies.