Common Eye Diseases

Dry Eye Disease

Iris Melanoma

Pannus

Progressive Retinal Atrophy

Retinal Detachment

Sudden Acquired Retinal Degeneration Syndrome

Corneal Sequestrum

Uveitis

Dry Eye Disease
Dry Eye Disease is a result of a lack of tear production. The medical term for this disease is "keratoconjunctivitis sicca" and is abbreviated.

"KCS". Tears normally function to keep the surface of the eye moist and healthy. Conversely, a LACK of tears causes the eye to become irritated and scarred. The clinical signs of KCS include heavy mucus production, redness, rubbing at the eyes, cloudy eyes, corneal ulcers, and even general lethargy. After an extended period of dryness, the surface of the eye (cornea) begins to accumulate dark scar tissue and blood vessels - to the point of blindness in many patients! This situation would be similar to having a complete layer of mud on your glasses.

The cause of dry eye is usually unknown but some known causes include: congential disorders (puppies), infections (canine distemper virus), drug induction (sulfa antibiotics), and removal of the tear gland of the third eyelid ("cherry eye"). KCS is seen very commonly in certain breeds of dog such as the Cocker Spaniel, Shih Tzu, Lhasa Apso, Bulldog, Schnauzer, and Westhighland White Terrier.

The treatment for dry eye disease has three objectives: 1) to stimulate tear production, 2) to lubricate the cornea, and 3) to decrease the scar tissue. Since 1987 we have used a drug called Cyclosporine to accomplish all three objectives. This relatively new drug is considered a breakthrough in the treatment of this disease, since it is about 75% effective in stimulating new tears in dogs. Although veterinary ophthalmologists have been using Cyclosporine to treat dry eye for years, the 2% solution is not yet approved by the FDA for use in the eye. Therefore, 2% solution is compounded by an approved pharmacy; a 0.2% ointment is commercially available (Schering) but many of our cases are very severe and require the more potent concentration of cyclosporine.

Cyclosporine HAS to be used absolutely as directed. If you skip a dose or run out of the medication, the dry eye signs will immediately recur. In addition, it is crucial that you have your dog rechecked as directed to monitor treatment success.

Topical steroids are also often used to help lubricate the cornea and decrease scar tissue. Appropriate aggressive treatment immediately following diagnosis will give a patient the best chance to repond to the drugs. Although most patients respond begin to do better right away, it takes a long time (months) for the tear production to get back up to normal levels, and even longer to reduce all the accumulated scar tissue.

KCS is a lifelong problem. Medications are used to control the disease, but you should not expect the condition to be "cured". However, in most patients, proper treatment will result in normal-looking, comfortable eyes. As the patient reponds over several months, Dr. Abrams may be able to suggest a reduction in the frequency of the medications. Changing the frequency is a delicate process, which is why periodic rechecks are required and changes to the protocol are made only at the doctor's suggestion. Most patients need to stay on medication at least at some frequency for the rest of their lives to keep the symptoms in check. BackToTop

Iris Melanoma
The iris is the colored part of the eye. In cats, an abnormally pigmented area of the iris may represent either a benign or a malignant lesion. There are two similar-sounding diagnoses which describe iris pigmentation in cats: iris melanosis and iris melanoma. These two terms are described below.

Iris melanosis is a general term meaning "discoloration of the iris". The pigmented area may be a small freckle, or the iris may have many diffuse discolored areas. Iris melanosis usually occurs in only one eye, but may occur in both eyes. Over time, the pigmented area often spreads to other parts of the iris. Iris melanosis may be a benign (harmless) condition, or it may cause secondary glaucoma if the pigmented area spreads and blocks intraocular fluid drainage.

In contrast to iris melanosis, iris melanoma refers to a malignant lesion of the iris. Melanoma lesions are more likely to be nodular and lumpy rather than diffuse and flat. If left untreated, the melanoma may remain unchanged, it may spread to other parts of the iris, or it may metastisize to other parts of the body and lead to fatal respiratory disease or liver failure. Aggressive treatment for iris melanoma involves complete removal of the eye. Conservative treatment for iris melanoma is similar to that for iris melanosis: periodic rechecks to watch for changes in the lesion and secondary complications. BackToTop

Pannus
Pannus is a term used to describe a syndrome that causes a "fleshy" type of tissue to accumulate in and on the surface of the eye, the cornea. The disease is seen more commonly in certain breeds, namely the German Shepherd, Greyhound, and Dachshund.

A special type of pannus known as plasmoma. Patients with plasmoma have a thickened and "lumpy" third eyelid. Plasmoma can exist in conjunction with pannus of the cornea, or it may occur alone.^

The cause of pannus is unknown but certain risk factors, namely, ultraviolet light, altitude, and breed are thought to be involved. Most patients respond to steroids or other drugs which suppress the local immune reaction; therefore, we think that pannus might be an "immune-mediated" disease where the body is producing antibodies directed against the cornea.

Control is the key word with this potentially blinding disease since most patients with pannus MUST continue with some frequency of topical medications for the remainder of their lives. We might be able to decrease the frequency of the treatment over time but we will always have to use the medications to some degree.

Followup visits are very important with this disease so that we can carefully monitor the patient's progress. If the medication is not effective, we might change to a different drug to suppress the local antibody reaction. BackToTop

Progressive Retinal Atrophy
Progressive Retinal Atrophy (PRA) is an inherited disease in many canine breeds, including the {breed}. The disease causes gradual blindness, first affecting dim light vision and eventually, resulting in complete blindness many months or years later. Since the vision loss is so gradual, most owners don't notice a problem until the blindness has progressed to a severe end stage. There is no known treatment for PRA at this time, as there is no known treatment for a similar disease, retinitis pigmentosa, in people. PRA is actually a collection of specific types of retinal degeneration depending on the breed so there are probably multiple causes.

Genetics play a vital role in the disease and therefore, individuals related to an affected patient should also be examined for PRA with an eye exam. The owners of related dogs may also want to have an electroretinogram (ERG) performed. The ERG is a sensitive indicator of PRA, often times revealing abnormal findings long before clinical signs are apparent.

Although PRA is a devastating disease in the eventual, complete loss of vision, it seems that all dogs do very well by adjusting to their environments and lifestyles by using their other senses. It is also fascinating to find a blind dog using the sighted dogs in the household as a guide! BackToTop

Retinal Detachment
The retina is the nervous layer of the eye, and it normally lies flat against the back of the eye. The retina is reponsible for collecting light impulses which are then transferred to the brain and interpreted as vision. When the retinas detach from their normal position, they cease to function and the patient becomes blind.

Retinal detachment can be caused by tumors, fungal infections, severe trauma, inflammation, genetic predisposition, high blood pressure, or immunity problems. Depending on what caused the detachment and how long the retina has been detached, in some cases the retinas can be reattached and vision restored. In many cases, however, the retina deteriorates and the prognosis for vision is poor. BackToTop

Sudden Acquired Retinal Degeneration Syndrome
Sudden Acquired Retinal Degeneration Syndrome (SARDS) is a bizarre syndrome in dogs. Most patients become blind very suddenly, usually in a matter of days to weeks. There is no known cause of the disease and unfortunately, there is no known treatment. This disease is the only one we known of that demonstrates a normal eye exam in the face of blindness, but the electroretinogram (ERG) is absolutely abnormal. The ERG is a measure of retinal function and when it is "flat", there is no electrical activity from the retina, the vital nerve portion of the eye.

Many patients (70%) have an associated problem where they will drink lots of water, eat aggressively, and gain a lot of weight in recent times. These signs hint at a hormone disorder called Cushing's disease, a similar disease to diabetes. However, when patients are tested for Cushing’s disease, the results are usually normal or borderline, therefore indicating that SARDS patients probably don’t have true Cushings disease. BackToTop

Corneal Sequestrum
A corneal sequestrum is a bizarre disease seen primarily in certain breeds of cats such as the Persian and Himalyan. A piece of the cornea, usually centrally located, dies for unknown reasons. This dead or necrotic cornea turns black and may involve only the surface layers or in severe cases, may penetrate to very deep layers of the cornea. Certain factors such as Herpesvirus, lack of tears, breed, or poorly healing corneal ulcers seem to correlate with the existence of corneal sequestra in some patients.

Surgery is often necessary to remove the sequestrum if the patient is uncomfortable. If the patient seems uncomfortable with redness, squinting, or discharge, we may have to remove the sequestrum.

Corneal sequestra can recur in the same eye or in the opposite eye at ANY time. This disease is OFTEN frustrating to the owner, patient,and to us because of the recurrent nature of the disease. Some cats require multiple surgeries but we will only suggest surgery if the sequestrum appears to bother the patient. BackToTop

Uveitis
Uveitis refers to an inflammation (irritation) of the part of the eye that supplies blood to the eye. If the eye is to remain clear so that light rays can focus on the back of the eye, the blood vessels must be located out of the way of the clear structures such as the cornea and lens. When the blood vessels become irritated, blood cells and debris leak out and result in cloudiness. Clinical signs of uveitis include: cloudiness, redness, tearing, squinting, bleeding into the eye, and loss of vision.

There are many causes of uveitis such as trauma or cataract formation. Many types of infections and tumors can cause uveitis in the dog and cat. Some of the infections in dogs include: Rocky Mountain spotted fever, infected uterus in females, hepatitis virus, and systemic fungal infections. In cats the causes can include: feline leukemia virus, feline AIDS virus, FIP virus, and Toxoplasmosis. However, many patients with uveitis DO NOT have an obvious underlying cause. We evaluate the entire patient to decide whether specific laboratory testing is necessary to search for a cause of the uveitis.

In some Golden Retrievers, the uveitis is of a particularly aggressive type. "Golden Retriever Uveitis Syndrome" is usually present in both eyes, is often a chronic, long-term concern, and is more likely than other types of uveitis to lead to secondary eye problems. Patients with this type of uveitis often need oral anti-inflammatory medications to control the inflammation.

Uveitis can result in several eye complications such as cataract formation, scar tissue, retina disease, and glaucoma. Treatment for this disease is aimed at reducing the inflammation and preventing the complications. The treatment protocol will vary for each patient but may include a steroid eye medicine to decrease the inflammation, aspirin to decrease inflammation, and possibly medicine to prevent glaucoma. BackToTop