Top 3 Diseases of the Surface of the Eye (Cornea) in Dogs
Any disease affecting the surface of the eye can threaten vision. Therefore, it’s important to treat them quickly and effectively. Below is a summary of the most common corneal conditions affecting dogs.
What is the cornea?
The eye surface, or cornea, is a very clever structure. It’s a specialized form of skin that covers the eye, keeping the internal contents protected. The cornea is transparent, allowing light to pass through and be processed in the deeper layers of the eye.
1. Dry Eye (Keratoconjunctivitis Sicca)
Keratoconjunctivitis Sicca (KCS), also called dry eye, normally occurs in middle-age and is caused by an inability to secrete enough tears. The first signs of dry eye include thick green discharge and conjunctivitis. Although strictly a disease of the tear gland, the result is a dry, sticky cornea that can become infected. In turn, this results in a cloudy or pigmented surface which can worsen and cause blindness if not treated.
Caught in the early stages, KCS is a very treatable condition. Treatment usually consists of eye drops such as cyclosporine and tear replacements. It’s important to note that the medications are LIFELONG and must not be discontinued. Commonly affected breeds include Bulldogs, Cocker Spaniels, and certain terriers.
2. Eye Ulcers
Any damage to the cornea causing a loss of integrity of the surface is called an eye ulcer. These can be superficial, affecting just the upper layers of the cornea, or deep. Ulcers can be caused by trauma, such as a scratch, or by foreign material such as small thorns that can even become lodged there.
An ulcer is in danger of becoming infected and spreading over a larger surface of the cornea. The cornea can repair itself effectively. However, most ulcers require treatment with antibiotic eye drops and some painkillers. They can progress quickly if they become infected and all require prompt veterinary attention.
There are some instances where ulcers don’t heal well and may require surgery:
- Deep Ulcers - often in short-nosed breeds such as pugs or patients with a complicating condition (such as dry eye). If the ulcer is deep or infected (or both) it may require aggressive treatment with a surgical graft.
- Non-Healing, Superficial Ulcers (also known as “Boxer” ulcers, indolent ulcers, or SSCEDs) - As the name suggests, certain breeds such as Boxers are prone to this condition where the ulcer tries to heal but fails. Certain surgical procedures can encourage further healing. Examples of which are a keratotomy, or diamond burr debridement.
Keratitis simply means inflammation or infection of the cornea. There is normally an underlying cause of this, though sometimes none can be found. Common causes of keratitis include dry eye, rubbing of hairs on the eye (particularly from nasal hair), or an inability to blink properly.
The latter is usually seen in short-nosed dogs with large eyes such as French Bulldogs or Pugs. These breeds will commonly get a dark pigment deposited on the corner of the cornea (called pigmentary keratitis) which can progress across the surface of the eye to cause blindness. Pigmentary keratitis can be treated with surgery to reduce the length of the eyelids and occasionally, removal of the pigment deposits.
Other Diseases of the Cornea
Less commonly, the cornea can become infected with fungus or yeasts. These may look like an eye ulcer but fail to heal.
The cornea can also become cloudy due to a condition called endothelial dystrophy. This is more common in humans but can be seen in geriatric patients or Boston Terriers.
All of these eye conditions are serious and potentially cause loss of vision in dogs. Therefore, seeking veterinary attention as soon as possible is very important.
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