Processing ....|
Common Eye Diseases Definition: In glaucoma the pressure inside the eye is too high. The eye is full of fluid. The fluid is constantly produced and drained from the eye and supplies nutrition for all parts of the eye. Glaucoma is caused by a decrease in the amount of fluid that flows out of the eye. This is a serious disease and without proper treatment it can result in blindness. Glaucoma is one of the most frequent causes of blindness in adult dogs. Types of Glaucoma: There are two main types of glaucoma, primary and secondary. In primary glaucoma, the cause of the increase in pressure is due to a problem in the drainage angle. It is frequently an inherited problem. Beagles, Basset Hounds, and Cocker Spaniels are prone to this type of glaucoma. In secondary glaucoma the pressure is too high because something else is wrong in the eye, such as a lens luxation, bleeding, inflammation, or tumor. Signs: Bloodshot (red) eye, painful eye, lids may be held shut, tearing, eye may appear cloudy or blue, sudden blindness, depression, appetite loss, enlargement of the eye. Treatment: The treatment chosen (i.e. surgery and/or medical therapy) will be influenced by what the goal of therapy is: to stop pain in a blind eye or to preserve vision. Medical treatment consists of a number of different drugs used in combination. Some are given by mouth and effect the whole body, while others are put directly into the eye and have a local effect. The drugs that work when the problem is first diagnosed may not work forever. Therefore, the intraocular pressure needs to be monitored on a regular basis so that the medication regimen can be altered to fit the needs of the patient. Unfortunately glaucoma cannot be cured, only controlled. When medical treatment fails, surgical therapy can help prolong vision. Medical Therapy: The following drugs are frequently used: Carbonic anhydrase inhibitors: Oral and topical formulations reduce the amount of fluid produced inside the eye. Miotics (Parasympathomimetics): Used on the eye, it helps to increase the outflow of fluid from the eye. It may cause a temporary redness, burning or stinging in the eye. Beta adrenergic blockers: Used on the eye, to reduce the amount of fluid produced inside the eye. *By using very small amounts of several of the drugs, the risks of side effects can be reduced. *Please keep these drugs out of the reach of children. Surgical Treatment: In some cases, there are surgical procedures that may provide permanent, or at least long-term control. One of these procedures uses a laser to destroy the part of the eye that produces fluid and thereby reduces the pressure. Another surgery inserts a tube into the eye that shunts the fluid under the conjunctiva (pink tissue) deep in the eye socket. Neither surgery is 100% successful and multiple surgeries over several years may be required to preserve vision. Blind, painful eyes can be removed to eliminate discomfort for your pet and to avoid the need for medicines that are expensive and affect the whole body. This surgery is called enucleation and the eyelids are permanently sewn shut. Remember: Each case is different and therapy must be tailored to the individual patient. Intraocular pressure must be measured regularly and the eye should be treated as prescribed. Do not stop any medication unless directed to do so by your veterinarian. KERATOCONJUNCTIVITIS SICCA (DRY EYE) What is KCS? Keratoconjunctivitis sicca (KCS) is also called dry eye. This condition is due to a deficiency in tear production and results in a red eye with a thick mucoid discharge. The tear production is measured by the Schirmer Tear Test. A standardized paper strip is gently placed on the eye and allowed to absorb tears for one minute. Wetting values of less than 15 mm per minute are abnormal. DRY EYE: Below are two dogs with dry eye. The cornea is the clear front part of the eye. Part of the reason it is clear is because the tears bathe the eye to keep it moist and smooth. In dry eye, the lack of tears results in the cornea trying to turn into skin. Blood vessels, pigment and thickening of the cornea occur so that the cornea appears dull and cloudy (photo on the left below). Tears are made of mucous, water and oils. Dry eye is a deficiency of the water (aqueous) part of the tears. Animal's with dry eye therefore accumulate a lot of mucous . Why does this happen? Acute KCS results in a very red and painful eye with some discharge. This may be associated with viral diseases, trauma, drug toxicity (some types of antibiotics), allergens, or anesthesia. Chronic KCS results in an off and on red eye with a profuse, ropy, thick discharge that adheres to the eye. Without treatment, the cornea may eventually pigment and scar to result in loss of vision. This can be familial in certain breeds, associated with immune-mediated diseases, secondary to chronic inflammation of the eye, or idiopathic (no known cause). How long will this problem last? Sometimes the condition resolves and spontaneous tear production begins. The acute form is more likely to resolve. Chronic KCS may or may not resolve, and those animals with lower tear values are harder to control. Medical therapy may need to be given for the lifetime of the animal. If medical therapy fails, surgery to transplant a salivary gland duct into the eye can sometimes help control the problem. The importance of recheck visits. The tear test should be repeated to monitor progress and improvement in tear production. Premature discontinuation of the treatment can allow the condition to worsen. Due to corneal pigmentation and scarring, the condition can cause blindness if left untreated. How is this treated? Acute KCS frequently has corneal ulcers associated with it and they must be treated aggressively with antibiotics and tear replacement. Both acute and chronic KCS are treated by topical tear substitutes as well as stimulation of existing tear production. Tacrolimus or Cyclosporine ointment (Optimmune, Schering Plough) are used to increase tear production and reduce inflammation. Sometimes tacrolimus or cyclosporine used 2x/day can control the KCS effectively without additional medications. Sometimes topical antibiotics and/or steroids are used in treatment of KCS. The tear film has natural antibacterial action which is replaced by antibiotic therapy. Anti-inflammatory drugs are frequently used to help control scarring and irritation. It is important to clean accumulated mucous from eyes or lids with eye wash and cotton balls prior to instilling medications. Be sure to keep all medications out of the reach of children. Follow the medication schedule that you will be given. Premature discontinuation of medication is the most common cause of treatment failure. Important Note: If your pet is on topical steroid (hydrocortisone, dexamethasone, or prednisolone), always call your veterinarian if any pain (squinting) develops. If a corneal ulcer develops, topical steroids must be discontinued immediately. When in doubt, stop topical steroids until the eye is checked by your veterinarian. The cornea is the front clear part of the eye. The corneal is covered with a clear epithelium. The corneal epithelium is like our skin except that it is clear and smoother. If the corneal epithelium is scratched, scraped or rubbed off a corneal ulcer occurs. A corneal ulcer is painful and animals with ulcers often squint their eyes. A corneal ulcer can be a sight-threatening emergency if deep or infected. PROGRESSIVE RETINAL ATROPHY (PRA) General Information Progressive retinal atrophy (PRA) is a name given to a broad group of eye diseases of similar character. PRA causes no pain or discomfort but may result in permanent blindness. The word atrophy means wasting away. PRA develops after birth and in some breeds has been determined to be inherited from both parents. It affects the retina, which lines the back portion of the inner eye. The retina contains the light-sensitive rods and cones that change light into energy for transmitting messages to the brain. The retina is similar to the film in a camera; the image or picture is received on it. PRA can occur in all breeds of dogs and cats although certain breeds are at higher risk. It appears earlier in some breeds and can take several years to cause complete blindness. An early sign of PRA is inability to see in dim light or at night. For example, an animal with PRA may hesitate to go from a well lighted room into a darkened room. Due to PRA's slow progress, most pets adapt very well to the gradual loss of sight. Many owners do not realize their pet is becoming blind. Animals compensate well for blindness, because their senses are much more acute than those of people. Important Points in Treatment 1. No effective treatment is available. 2. Complete blindness eventually results. The condition, however, is not painful. 3. PRA is prevented through selective breeding of animals with normal eyes. 4. Sometimes cataracts develop secondary to the retinal degeneration. Notify the Doctor if Any of the Following Occur * You notice a sudden change in your pet's vision or eyes. * Your pet shows pain or discomfort. |
