Last week we spoke about eye problems in dogs. Now, we’ll take a look at internal eye diseases of dogs in greater detail. Conjunctivitis (or “dog pink eye”) is used to describe the conjunctiva when it becomes reddened, congested, and painful. There may be an abnormal amount of discharge coming from the dog’s eye, often collecting around the eye area and limiting the dog’s ability to blink or open the eye fully. The surrounding eye tissue, including the eyelid, may be inflamed. This may occur in one or both eyes, depending upon the cause. The conjunctiva is the thin membrane that lines the inner surface of the eyelids and covers the white portions (sclera) of the eyeball. It is a protective layer that contains special glands whose secretions help maintain normal eye health. Causes of conjunctivitis include foreign matter, chemicals, bacteria, viruses or other germs, polluted water, or smoke; birth defects, serious internal diseases, and allergic reactions. The first step in treating pink eye is making sure the eye and the surrounding area are clean. Use a soft, clean cloth to wipe away excess dirt, discharge and foreign bodies. If you think that there might be something lodged in the back of the eye, try flushing out the eye with lukewarm water and take the dog to your veterinarian to have it removed.
Corneal ulcers are more complex dog eye injuries and are usually caused by trauma, infections, and nutritional deficiencies. The cornea is the transparent front layer of the eyeball. It consists of several complex layers and is the most sensitive part of the eye. Ulcerative keratitis is corneal inflammation caused by disruption in one or more layers of the cornea, starting from the outside going inward. The disruption (ulcer) may be very shallow, similar to a scrape or an abrasion, or it may be very deep, nearly penetrating all the corneal layers. The deeper the ulcer is; the more vision is threatened. Corneal ulcers are quite painful, and treatment to reduce discomfort will be given. Cataracts cause the clear lens behind the pupil to become cloudy or white, eventually to the point of blindness. Cataracts can sometimes be confused with nuclear sclerosis which is a common with ageing. With nuclear sclerosis, vision can become blurry but it does not lead to blindness. While cataracts are usually genetic, they can be a result of injury or stem from chronic disease or immune problems. For non-injury related cataracts, removing the lens surgically can help (this surgery is now available locally at the School of Veterinary Medicine Hospital—645-2640).
Glaucoma is a disease in which pressure within the eyeball increases to dangerous levels. It is one of the most common causes of blindness in dogs and cats. The maintenance of normal pressure within the eye depends upon a delicate balance between production and escape of internal eye fluid (aqueous humour). The eyeball may become enlarged if glaucoma persists over a long period of time. The causes of glaucoma include blockage of the drainage passage due to birth defects (possibly inherited), inflammatory conditions, injuries tumors, blockage of the pupil, and lens disorders. Vision may be permanently destroyed within hours if the internal eye pressure is high enough. Uveitis is inflammation of the iris, ciliary body, and choroid. These major structures of the eye are very sensitive and perform numerous functions required for vision. Causes include inflammation, infection, immune-mediated reactions (a complex allergic-type reaction), and injuries. Enucleation is the surgical removal of the eyeball. It is a last-resort treatment for very serious eye diseases or injuries such as cancer of the eye. Modern surgical techniques allow minimum disfigurement and maximum comfort to the patient. This procedure is an acceptable, humane alternative to destruction of the animal. Do’nt worry; animals adjust very well to single-eyed vision or even to blindness if their environment remains constant. Dogs use their sense of smell first and foremost, but eyes still must be treated with care.