to the Cornea
or Surface of the Eye
What's On This Page:
Corneal Injuries & Ulcers
Kerratitis Sicca or Dry Eye
Other Topics Related to Eyes On Other Pages:
Pannus; autoimmune? disease of the cornea most often seen in German Sheperds
More Information soon about these eye disorders:
inflammation of the inner lids and tear glands
Viral Infections of the eye
Bacterial infections of the eye
How metabolic diseases sometimes affect the eye
The cornea is the clear, window like surface part of the eye. It's exposed to wind, grit, scratches, and wounds.
We use the term ulcer fairly loosely to mean any wound to the cornea, whether it be a scratch, a dent, any other small wound, or a necrotic, soft spot on the eye.
Signs of a corneal ulcer include squinting, watering or redness of the eye, a cloudy spot on the cornea, or a dimple on the surface of the cornea.
Diagnosis is made by careful visual exam, often with the help of a special dye called fluorescein. Your vet will then try to determine the cause of the damage.
Common causes of ulcers include viral infections (especially in cats), trauma (scratches & pokes to the eye) and bacterial infections. Combinations of trauma and bacterial infections are especially common.
Sometimes the cornea is damaged ... or heals poorly ... because there aren't enough tears, or the tears don't cover the center of the eye well, leaving it dry and poorly lubricated. (See my comments about "dry eye" or keratitis sicca below)
Sometimes the cornea is damaged because of eyelashes that point in instead of out so that each time a pet blinks, the eyelash rubs against the eye.
Sometimes there are underlying metabolic diseases (such as hypothyroidism) or autoimmune diseases (such as pannus) that are factors in your pet's corneal disease.
Even dental disease (root abscess of the tooth under the eye) can be the cause of your pet's corneal infection.
So expect your vet to carefully examine not only your pet's eye but also a general physical and oral exam.
Treatment usually includes the topical administration of antibacterial or antiviral eye drops. Additional drops or ointments may be prescribed that will dilate the pupil of the affected eye in order to relieve ocular muscle spasms. The frequency of this treatment depends on the severity of the ulcer (and the temperment of the pet). Your veterinarian will advise you.
Sometimes surgical treatment is needed to cure a damaged cornea. Here are some types of surgery that might be considered for corneal lesions:
Different types of Flap Surgery: Suturing the conjunctiva (the moist pink tissue surrounding the part of the eye that you can't see easily) or the 3rd lid up over the damaged cornea and leaving it sutured for a couple of weeks is often very soothing and healing. It doesn't always work, but it's a surgery that most general practioners are capable of doing well, and it's relatively inexpensive.
"Micro" Surgery: Wounds to the eye can be debrided and sutured, lasered, or glued. This type of surgery requires more specialized equipment and experience, so many general practioners may refer cases where such intricate surgery would be appropriate. Corneal surgical repairs are often combined with a flap surgery to help improve healing.
Salivary Duct "Artificial Tears" Surgery: Wow. If your pet suffers from a lack of tears (sometimes associated with metabolic diseases such as hypothyroidism). there's a surgical technique where the pet's salivary duct can be rerouted under the skin to the upper lid so that saliva will be dripped over the eye. I've personally have never done this surgery. I suspect that you get a lot of "extra" tears at feeding time!
Keratitis Sicca or Dry Eye
(Keratoconjunctivitis sicca or KCS)
Introduction: Some dogs seem to have frequent eye infections and that's often because they have poor tear production or poor tear distribution over the surface of their eyes.
Causes include damage to the tear glands from distemper virus, as a side effect from medications such as sulfa drugs, from removing the tarsal gland (cherry eye) and for genetic reasons. This is a common problem in Cockers, Schnauzers, Westies, Shih Tzu's, and Lhasa Apso's. This seems to be a rare problem in cats.
Symptoms include corneal ulcers (see article above), blood vessels tracking across the surface of the eye, eye discharge, secondary conjunctivitis, pain and discomfort. Left untreated, the surface of the eye will eventually be covered in pigmented scar tissue and will be chronically painful and infected.
Diagnosis. We vets often miss this disease at first assuming the problem is a simple conjunctival infection due to underlying trauma or allergies. The symptoms are very similar. But if the problem keeps recurring we quickly become suspicious and can cheaply confirm the diagnosis with a Schirmer Tear Test.
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Includes information about Prescription diets used to treat disease, and a discussion about the pet food industry
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The eye above has a conjunctival infection, uveitis (infection inside the eye) ... all secondary to dry eye
The cat above and the dog below are having a quick, painless, and accurate check for glaucoma (high pressure in the eye). This page is about corneal lesions and dry eye (also known as Keratitis Sicca). But remember that everything is connected. Corneal disease often leads to glaucoma and blindness.
A. Treatment of the infection with topical and/or systemic antibiotics
B. Pain management as needed
C. Eye cleaning as needed
D. Eye lubrication with some combination of the following products:
Cyclosporine eye ointment or drops are now most vet's first choice of treatment because of the high success rate of this treatment. Cyclosporine stimulates tear production and aids in corneal healing. It's fairly expensive, it doesn't work all that well in about 25% of dogs with dry eye, and if you get lazy and don't use it regularily, the eye will quickly go back to being dry, cracked, and infected.
Tacrolimus drops have to be compounded by a compounding pharmacy but often helps for those cases where cyclosporine didn't work well. Tacrolimus reduces inflammation associated with autoimmune disease and also stimulates tear production. It is even more expensive than cyclospoine and also has to be used regularily or any improvement will quickly regress
Hyaluronic Acid eye preparations have been difficult to get in the United States but it is cheaply available in a diluted form in some eyewashes. This is interesting... The fluid inside the eye has a high concentration of hyaluronic acid in it and eye surgeons discovered that a drop placed on the ocular surface protected the cornea after surgery.
Subsequent studies found that hyaluronic acid relieves dry eye symptoms and reduces ocular surface damage without triggering allergic reactions.
To save money for my clients, I often try using the diluted hyaluronic acid artificial tear products instead of cyclosporine for maintenance once the more expensive product gets the eye back to normal. Success has been fair
I think that more concentrated forms of hyaluronic acid eye preparations are available in Japan and Europe. In the U.S.
the FDA placed restrictions on the original commercial product, which was derived from rooster combs—the FDA has long looked unfavorably on such biological extracts due to the risks of contamination and the transmission of infectious disease.
Artificial Tears are inexpensive and helpful but not typically good enough to control this problem.
The Schirmer tear test is simple and inexpensive.