C. Ann,
You should really check into this more. A lot of insurance companies won't cover anything "related to vision"; however, if it becomes a medical problem, then it will go under the medical insurance.
For instance, I have not vision coverage and for me to go to an opthamologist for vision care, it is at my own expense.
Several years ago, I started having severe dry eye, due to a medical condition--most likely rosacea. I have to see an opthamologist to get it diagnosed and get the special eye drops. It all ended up being covered under my medical insurance.
I cannot believe that if you are essentially LOSING your vision due to a structure abnormality of your eyelid, that your medical insurance would not cover this. I think you need to see a doctor about it and, if they write it up correctly, it will be covered.