Corneal ulcers are scratches, abrasions or erosions on the front surface of the eye. The cornea is the glass ball in the front of the eye so if I poked you in the eye, I’d be touching your cornea. In dogs and cats damage to the cornea is a very common occurrence, because they lead with their head and often hit things that can bump or damage the eye. Dogs can also get corneal ulcers from rough-housing or rubbing their head on the ground. Cats sometimes get corneal ulcers from fighting with other cats.
Corneal ulcers are one of the most common eye problems that we see in small animal medicine. Common signs of corneal ulcers in dogs and cats include squinting, redness in the sclera (the part of the eye that is normally white), abnormal discharge from the eye – either watery or mucousy – and sometimes cloudiness or haziness to the eye itself. Corneal ulcers are routinely painful, and sometimes the pet will rub its eye with its paw, or rub its head on the floor.
The cornea is made up of four layers. Typically corneal ulcers affect the top one or two layers. There can be damage to either the first +/- second layer without us being able to see the damage, even with an ophthalmascope. Therefore, anytime we see any redness or soreness in the eye, we’ll always stain it to check for a corneal ulcer.
Diagnosing a Corneal Ulcer
We use a fluorescent stain on the eye to identify corneal ulcers. In a normal healthy intact cornea the stain that we apply to the eye will wash off without leaving any residue. However if the top layer of the cornea has been eroded, then either the second or third layer of the cornea will be exposed, and these layers do absorb the stain. So after we rinse the eye, any stain uptake in the exposed second layer will present as a bright apple green dot.
It is important to identify corneal ulcers when they first present, as unattended ulcers can rapidly deteriorate and ultimately lead to perforation of the eye. Also, treatment of the eye is vastly different for an eye with a corneal ulcer than it is for a simple eye infection.
Treatment of Corneal Ulcers
Treatment of corneal ulcers includes topical antibiotic drops, anti-inflammatories, and usually an Elizabethan collar to keep the pet from damaging the eye. Also, we now use a new medication that helps repair the cornea by reestablishing the underlying stroma. We have found that using this new treatment regimen – called ReMend – helps to decrease our healing time by up to 30%.
In advanced cases of corneal damage, or cases in which the damage is deep into the corneal stroma, we’ll sometimes use a conjunctival or third eyelid flap. Conjunctival and third eyelid flaps are both designed to help protect the damaged area of the cornea. Conjunctival flaps are more technically demanding, but have the added advantage of supplying additional blood supply and healing capability to the damaged cornea, whereas third eyelid flaps are for protection purposes only.
The bottom line is that corneal ulcers are very serious injuries, and anytime you think your pet might have damaged his cornea, medical attention is definitely warranted.