What is it?
A corneal ulcer is a "scratch" on the front of the eye (the cornea being the transparent window in the front). Although the eye is quite capable of healing itself, damage to the cornea can easily become infected, resulting in scarring and, if not rapidly treated, vision impairment.
What causes it?
The most common cause is running through long grass! As the dog runs, the grass whips back in their face and, while the blink reflex is really fast, it isn't always quite quick enough to avoid a grass cut to the cornea. Other common causes include cat scratches (cats always go for the eyes or the nose) and grass seeds and other debris blown on the wind - when running in grass or if dogs stick their head out of a moving car window (which, by the way, it's a really bad idea to let them do!). However, an ulcer doesn't only happen because of trauma - excessive dryness can cause part of the cornea to die and peel away, giving a similar effect. This is seen in dogs with Dry Eye, and those whose eyelids don't meet in the middle properly.
What dogs are at risk?
Absolutely any dog may get a corneal ulcer due to trauma. However, dogs with protuberant eyeballs (like pugs) are at highest risk of getting an ulcer because their eyelids don't close properly to protect and moisten the corneal surface. In addition, some breeds (such as Boxers) are at an increased risk of developing an indolent, or non-healing, ulcer if they do get an eye injury.
What are the symptoms?
A corneal ulcer, whatever the cause, usually presents with what we sometimes call the "PLB Triad" - Pain (the eye is obviously sore and often they'll rub at it); Lachrymation (running eyes); and Blepharospasm (the eye is held closed). If it's been there a while, it may become less painful and they'll open it again; you may then see a milky scar on the eye, and blood vessels growing in from the edges to help repair the damage.
How is it diagnosed?
We look into their eye with an instrument called an ophthalmoscope, and then put some dye into the front of the eye (usually fluorescein, but occasionally others). These dyes stick only to damaged corneal tissue, and glow when exposed to blue light, so we can see where, and how large, the damaged area is.
How can it be treated or managed?
The majority of corneal ulcers will heal rapidly with conservative treatment - antibiotic eyedrops to prevent and treat infection, and painkillers to reduce the discomfort and swelling. However, if an ulcer doesn't want to heal (these are called "indolent ulcers"), or starts to get bigger (e.g. a "melting ulcer"), there are a wide range of different treatment options we can use. These include plasma drops (where your dog's own blood is collected, processed, and then applied to the eye to prevent melting or widening of the ulcer) and EDTA drops (same reason). At the same time, a temporary soft contact lens may be fitted to protect the area while it heals. Surgical treatment may also be needed; the most common techniques are a Grid Keratectomy (where the eye is scored under anaesthetic to encourage healing) and Pedicle Flaps (where part of the lining of the eyelid is temporarily attached to the eyeball to help it heal).
Can it be prevented?
In most dogs no; however "doggles" (goggles for dogs) may be useful to protect the eyes of pets with especially bulging eyes.