What is the cause of severe dry eyes?

I been using advaced oyasys contact because of dry eyes, also using rewetting eye drop, but still my eyes are getting drier and contact is not comfortable, i wonder why?

There is a disease called scleroderma that affects the skin and the mucous membranes. It's one of those autoimmune diseases like rheumatoid arthritis and multiple sclerosis. You might want to read up on it and see if you have any other symptoms. Also, there may be something wrong with the contacts. See an ophthalmologist if the problem doesn't clear up soon.

I am so sorry. The disease I was thinking of was Sjogren's syndrome, not scleroderma. (Both are autoimmune diseases.)

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Your eye is not getting enough oxygen. I have this same problem, and I can't wear contacts.
pollen, air pollution, dust, and low humidity causes my dry eyes.
There is a condition called dry eye and has something to do with your tear ducts I'm not sure on the specifics. Talk to your eye doctor about it again. There are also eye drops called Thera-tears that are for dry eyes. But you can't use them when your contacts are in. You use them at night or 1/2 hour before you put your contacts in. It helps to replenish the protective layer on your eye. It helps me.