
Have had it in dogs and cats too many times. If they are stitched, they need to be kept closed for several weeks, and if the stitches come undone, will need to be redone again. The trouble with ulcers is that they CAN cause the eye to rupture. I've had that happen in cats several times. One cat the vet managed to repair a ruptured eye in three times (this was twice in one and once in the other), another's rupture was so total (virtually nothing left of the eye, it just literally burst like a balloon) he had to have his eye removed.
They do need eye drops whilst the eye is stitched, many times a day (seem to remember it was 8), and usually they give atropine drops also to enlarge the pupil behind the closed lids as that apparently helps.
If there has been no improvement after as long as 6 weeks, I'd be very inclined to ask for a referral to an eye specialist.