Can develop with underlying systemic autoimmune disease (RA, Wegener's, SLE, polyarteritis nodosa, UC, relapsing polychondritis, rosacea)
Usually unilateral and limited to 1 sector of cornea within 2mm on limbus. Epithelium absent in most cases and stroma thinned.
Rx with lubrication, topical collagenase inhibitors (sodium citrate 10%, acetylcysteine 20%, medroxyprogesterone 1%, tetracyclines), topical cyclosporine/steroids
Excision of adjacent conj (removes source of inflammatory cells)
Oral prednisone needed as local measures at not sufficient alone
If threatened perforation: cranoacrylate glue and bandage contact lense