What is the cornea?

The anatomy of a dog and a cat’s eyes are generally similar to humans, except for some key differences like the third eyelid which adds an additional layer of protection, and more rods in the retina which makes their eyes more powerful than ours.

The cornea is the transparent, outer membrane of the eye that serves as a layer of protection for the sensitive structures and parts inside. The cornea consists of three layers, all made up of highly specialized cells. The outer layer, called the epithelium, is a very thin layer of skin cells. Below it is the stroma, a layer of tissue that provides structural support to the entire cornea. The deepest layer is called Descemet’s membrane.

What is a corneal ulcer?

A corneal injury is any damage or erosion that occurs to the layers of the dog or cat’s cornea. If the damage only affects a few layers of the outermost epithelium, it’s only considered a corneal abrasion. A corneal ulcer is an erosion affecting both the epithelium and the stroma. When the stromal layer of the cornea is damaged, it leads to the accumulation of fluid in the stroma which makes the eye appear cloudy.

Deep corneal ulceration that damages the Descemet’s membrane is called a descemetocele. This is considered a serious injury, with a very high risk of permanent, irreversible damage and complications.

Causes of Corneal Injury in Dogs and Cats

The most common cause of corneal ulceration in pets is physical trauma. It may result from blunt trauma such as when a dog or a cat rubs their eyes on a particular surface, or due to a laceration or penetration by a sharp or pointed object. Chemical burns from harsh shampoo or irrigating solutions can also result in corneal ulceration in dogs and cats.

Other less common causes of corneal ulceration in pets are bacterial and viral infections. Certain conditions like keratoconjunctivitis sicca (dry eye), epithelial dystrophy, and several hormonal diseases can also predispose a dog or a cat to develop corneal ulcerations.

Symptoms of Corneal Ulcers in Pets

Corneal ulceration is a painful condition, and dogs or cats suffering from it will show signs of pain and discomfort such as squinting of the affected eye, inability to open the eyelids, a decrease in appetite, and possibly lethargy or reluctance to move around or play.

The affected eye may appear red due to inflammation. The white part of the eye, called the sclera, may become bloodshot, and the conjunctiva around the eye may swell up depending on the extent of the injury. The cornea will appear cloudy and will sometimes have a pinpoint white lesion in the middle where the ulceration is.

In cases of descemetocele, the ulcer will contain protruding tissue due to the leakage of the Descemet’s membrane to the outer layers of the cornea.

How do I know if my pet has a corneal ulcer?

In any cases of suspected eye injury, your vet will perform a thorough ophthalmic exam to assess the condition of the eye and the extent of the damage. To confirm the presence of a corneal ulcer, the vet will perform a fluorescein dye test on the affected eye.

Fluorescein is a special stain that is dropped on the corneal surface of the affected eye. Any erosion on the outer epithelium or stroma of the cornea will take up the dye and can be visualized if illuminated with a UV light. The presence of bright fluorescein stain on the surface of the cornea is confirmatory of corneal ulceration or abrasion.

In the case of descemetocele, the stain will occur around the deep ulcer as the Descemet’s membrane does not absorb or take up the fluorescein dye. It will appear as a bright, circular stain halo around the main deep ulcer.

Treatment Options for Pets with Corneal Ulcers

Treatment for corneal injury depends on the extent of the damage. Superficial corneal abrasions usually heal on their own in a few days, and your vet may prescribe eye drops to help speed up the healing process.

Deeper corneal ulcerations may require a more frequent application of serum eye drops to help with corneal healing. Your vet may also prescribe antibacterial eyedrops to prevent secondary bacterial infections, a common complication in cases of corneal ulcerations. Pain medications and anti-inflammatories can help manage pain and reduce the inflammation of the affected eye.

Descemetoceles will require a surgical procedure, called temporary tarsorrhaphy. This is a procedure that temporarily closes the eyelids of the affected eye to facilitate faster healing and prevent any irritation from environmental hazards. Antibiotics, pain medications, and anti-inflammatory medications are still necessary to manage pain and prevent any secondary infection.

Can corneal ulcers be treated at home?

If you start to observe any of the signs or symptoms mentioned above, it’s always best to bring your pet to your veterinarian immediately for a proper and thorough exam. If you suspect that the eye injury could have resulted in a corneal abrasion or ulceration, you can do the following as a first-aid treatment before or en route to a veterinary hospital.

• If able, rinse the affected eye with warm, distilled water to remove any possible foreign object that may have been lodged in your pet’s eye and caused the injury.
• Make your pet wear an Elizabethan collar (plastic cone) to prevent any further injury or damage to their eyes.
• Check the entire body for any signs of other possible wounds or injuries.
• DO NOT attempt to use any eye drops you have at home without a vet’s prescription or recommendation.

Read more:

What is Cherry Eye in Dogs?

A Vet’s Advice: Eye Exams and Eye Care for Your Pets

What causes itchy eyes in pets?

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