What is Dry Eye in Cats?
Dry eye in cats, also known as keratoconjunctivitis or KCS, is not an uncommon condition in cats. Dry Eye occurs when the proper amount of tears are not produced by the glands above the eye in the cat's third eyelid. As a result, the cornea of the eye becomes dry, inflamed, and irritated.
KCS is usually defined by the tear glands’ inability to produce water in the tears. Due to the fact that tears are a combination of mostly water with an addition of oil and mucus, if left untreated KCS will result in eyes which have a thick oily mucus layer over the eyes. In most cases, both eyes are affected.
With time, the cornea can become scratched and scarred, and blindness will eventually occur. Dry eye is also a notoriously painful condition, and cats with this illness may also suffer from depression and irritability as a result of their pain.
Which cats are susceptible to dry eye?
Cats may suffer from KCS at any age, and cat breeds of all kinds are susceptible to the condition. In most cases, dry eye in cats is due to an infection of feline herpesvirus. KCS treatments are available, and fortunately newer types of surgical and nonsurgical treatments have improved the manageability of dry eyes.
Causes of Dry Eye
Dry eye in cats, also known as keratoconjunctivitis sicca or KCS, usually occurs as a result of chronic feline herpesvirus illnesses. This is a highly contagious respiratory disease, and once a cat has this disease it can be treated but never cured. The disease may remain in remission for years, but if the cat becomes stressed or ill it can emerge again and KCS may appear as a result. Cats and kittens that live in overcrowded and unsanitary conditions are at a high risk of becoming infected with feline herpesvirus. The good news is that cats can be vaccinated for feline herpesvirus, and as a result many cases of KCS in cats are preventable.
Removal of the Third Eyelid
Removal of the third eyelid due to cherry eye can also cause KCS because the third eyelid produces a great portion of the tears that keep the eye moist. Fortunately removal of the third eyelid is no longer a popular treatment for cherry eye. Instead, the eyelid is positioned back into place and tacked down to permanently hold it in its proper position.
Injury to the Eye
In rare cases KCS may be caused by an injury to the eye, but this can only happen if somehow the eyelid glands above the eye or on the third eyelid are injured. When this does occur, it is most often due to cat fight injuries.
Symptoms of Dry Eye in Cats
What to Watch for
Cat owners should know what to look for in their cats when considering the possible existence of dry eye. The most obvious warning sign is a thick yellow-green discharge of mucous that forms at the corner of the eyes. Inflammation of certain parts of the eye, like the thin membrane that lines the eyelid or the cornea, could also occur.
But a cat might let his owner know all by itself. That’s because the pain and discomfort caused by dry eye will likely lead to the cat constantly pawing at the eyes in a futile attempt at some relief. That should be a telltale sign that the cat should be taken to see a veterinarian.
Some of the common symptoms of Dry Eye include:
- Swelling of the eyelids
- Red eye membranes
- Rubbing of the face
- Sensitivity to light
- Eye(s) swelling shut due to eyelid spasms
If left untreated, KCS can permanently affect vision.
The keratitis often progresses to a corneal ulceration or a loss of the protective layers of the cornea covering the eye surface. Eventually, new blood vessels form right on the usually transparent cornea, and sometimes pigmentation develops there as well.
Treatment Option for Dry Eye in Cats
Non-surgical treatment options for dry eye, or keratoconjunctivitis sicca (KCS) in cats involves using a number of lubricating eye drops in addition to drops which cut through the mucosal layer that forms over the eye in KCS conditions. Cats that are suffering from KCS due to chronic feline herpesvirus may benefit from supportive immune therapies.
While there are non-surgical treatment options for dry eye in cats, some cats do not respond well to these treatments, and in some cases pet owners are not able to administer the amount of drops needed to effectively treat the condition. When nonsurgical treatment options fail, a surgical procedure known as parotid duct transplantation may be used to treat dry eye.
Non-Surgical Treatment Options
Eye drops that are used to treat KCS in cats include artificial tears, antibiotic eye drops that are used to clear any existing infection, and mucolytic eye drops which help to dissolve the thick mucosal layer on the eyes. Mucolytic eye drops are needed to reduce scratching on the cornea and increase the effectiveness of the other eye drops that are administered.
Artificial tears will need to be administered at least four to six times a day to prevent KCS. Two types of medications, cyclosporine and pilocarpine, may also help to increase tear production. Cyclosporine is administered in eye drop form, and pilocarpine is usually mixed in the cat’s food. However, it is still debatable if these medications really help to increase tear production in cats.
Antibiotic eye drops are usually needed for a short period of time to clear up inflammation and infection that occurred when the eye became dry. Once the eyes remain lubricated, then antibiotic drops should no longer be required. Mucolytic eye drops such as acetylcysteine are needed throughout the treatment, in addition to artificial tears, to ensure that a layer of mucus does not continue to build on the eye surfaces.
Chronic feline herpes virus cannot be treated, but bouts of the virus can be controlled through antiviral medications, nutritional support, and creating a stress free environment for the cat.
Surgical Treatment Options
In mild to moderate cases of dry eye, also known as keratoconjunctivitis sicca (KCS), in cats, eye drops can be used to treat the condition. However in severe cases, eye drops may need to be applied almost once an hour, and for many pet owners it is impossible to maintain this medication regimen. In addition, severe cases of KCS may not be treatable with eye drop therapy alone. While parotid duct surgery is only used as a last resort treatment for KCS in cats, in severe cases of the condition it may be the only way to treat dry eyes.
Parotid Duct Transplantation
Parotid duct transplantation surgery moves the salivary glands, which are located on each side of the cheek, to a position near the eyes where they can serve as additional tear ducts. While the saliva glands do not produce tears, the saliva often works well as a synthetic tear material.
While parotid duct transplantation is an effective treatment option for dry eye in cats, there are a few downsides to the procedure. The first downside is that parotid duct transplantation is most often performed on dogs, and it can be very difficult to find a doctor that is capable of performing this surgery in cats. Secondly, the surgery can be very expensive. There are also complications from the surgery such as skin infections around the eye as a result of too much saliva and mineral deposit build up on the eye which can cause scarring. In many cases, periodic eye drops are still needed after the surgery to help cleanse the eyes and reduce mineral deposit buildup.