That is how it started with my "Dory", although it started more along the lateral line. I thought at first maybe it just scraped itself or something, but after a little while(a couple of weeks) some more little spots of erosion along line and now she does have a little area around her eye on the one side. She eats, and has grown with this disease from about 1.5" to now, I'd say she is about 4" or so. I am hoping that through diet, I can sort of keep it from getting worse, it is slowing, but like I said, I think it may be a losing battle. Part of the problem at first was that she sleeps in a very tight crevice at night, and I thought she was just injuring herself at night time. Good luck with yours, I hope yours and mine for that matter, live a long time, I do wonder if they are suffering in any way though. Mine seems very content???
I feel your pain, I wish I could give you more answers, I don't know if it is even understood totally by the formally educated ???.
Matt