CORNEAL OPACITY IN CATTLE—MANAGEMENT & TREATMENT
Compiled & Edited by-DR RAJESH KUMAR SINGH, JAMSHEDPUR, JHARKHAND,INDIA
9431309542,rajeshsinghvet@gmail.com
The cornea is considered as the clear window in front of the eyes through which light enters the eye and subsequntly reached to retina, where image of the object is created. A corneal opacity or scar will prevent the light and the image from being properly transmitted to the retina .Images can become distorted, leading to decreased vision. Several factors such as advancing age, atopic dermatitis, exposure to ultraviolet light, genetics and diabetes are thought to be associated with this pathological condition of eyes . However beside those, trauma and vitamin A deficiency are considered to be the main cause of corneal opacity in case of elephant and cattle. Opacity can be white, red or even pigmented based on the nature of etiology . Opacity of cornea may lead to temporary or permanent loss of vision if not treated. With the advancement of corneal opacity, ability of vision gradually reduced. As a consequence, vision could be lost temporarily or permanently due corneal opacity.
The cornea is the outer, transparent layer of the front of the eye. It protects the eye while still allowing light to pass through. The cornea is protected by a layer of tears and by continuously replacing its superficial cells. It lacks blood vessels (which helps make it transparent), and so does not heal easily. Any disease process or insult to the cornea can result in cloudiness, swelling, or pigmentation, which in turn may lead to loss of vision. Corneal irritation or inflammation is extremely painful. It is critical to treat any corneal problem as rapidly as possible.
1. Abrasions, Lacerations: —–
Any animal can suffer from a traumatic corneal abrasion, scratch, or laceration. Mild injuries can result in a superficial abrasion. Deeper wounds are identified as penetrating or perforating. A penetrating laceration involves the cornea, but does not pass through it. A perforation goes entirely through the cornea. If wounds are caused by a penetrating or perforating object, the object may still be in the cornea. Wounds can be caused by any object that can contact the eye. The same things that can cause conjunctivitis (feeding on coarse hays, bacterial infections, etc.) can also lead to corneal lesions.
Signs of a corneal wound include—–
pain and inflammation of the eye. The eyelids may be kept closed and the animal may resist examination. The wound may be visible on the cornea, along with swelling, cloudiness, and hemorrhage.
Diagnosis ——
is made by history and physical examination. An immediate diagnosis can be made if the object that caused the wound is still in the eye. Additional testing is done to determine the severity and extent of the wound, assess vision, and identify trauma to other portions of the eye and face. Bacterial culture and sensitivity may be necessary. A specific test called a fluorescein dye test is performed using special stain to ascertain if the cornea is intact or if it has been perforated.
Treatment ——
depends on the severity, depth, and age of the wound. Care should be taken to apply only minimal pressure to the face and eye to prevent rupture of the eyeball. Any foreign body should be flushed out, removed with a dampened cotton-tipped applicator, removed with forceps, or surgically removed from the eye. Superficial wounds can be treated with topical medications to prevent infections and calm the eye. Topical eye medications include antibiotics and atropine.
Extensive corneal lacerations and corneal penetrations require surgical repair. Surgical repair will also be needed for those injuries that contain a foreign body that is not easily removed. All corneal wounds should be rechecked at specific intervals to monitor healing. Superficial wounds can be checked at 3 day intervals; deep wounds should be checked daily for the first several days.
Prognosis ——
depends on the extent of the wound and the time elapsed between injury and veterinary treatment. The deeper the wound, the poorer the prognosis. Most superficial corneal abrasions and wounds heal quickly and satisfactorily. Deeper wounds or those created by blunt trauma may result in permanent loss of vision, inflammation, and pain. The full extent of the damage caused by the wound may not be apparent for days to weeks following the injury, so re-examination is necessary.
2.Keratitis: ——
Keratitis refers to inflammation of the cornea. Signs may include swelling (edema), cloudiness, and pigmentation.
Ulcerative Keratitis: This refers to inflammation of the cornea accompanied by ulceration of the surface of the cornea (a corneal ulcer). This is a very common condition in all animals.
Ulcerative keratitis can be caused by any condition that disrupts the layers of the cornea, including trauma, entropion, ectropion, trichiasis, keratoconjunctivitis, damage to the nerves of the face, and burns caused by chemicals and cleaners. Infection by bacterial or viral organisms may occur secondary to other irritations and injuries.
Ulcerative keratitis is a very painful condition. Signs of disease include tearing (lacrimation), spasms of the lids, squinting, spilling of tears onto the face (epiphora), avoidance of sunlight (photophobia), redness, and discharge from the eye. One or more defects in the cornea may be visible and are referred to as corneal ulcers. Some ulcerative keratitis cases have a mushy, gelatinous appearance as the cornea breaks down due to excessive enzyme production; this is sometimes called a “melting” ulcer. Chronic ulcers may show vascularization, scarring, pigmentation, and swelling. Healing ulcers may have a hazy, white appearance. Fluorescein dye testing helps to determine the depth, severity, and number of ulcers.
Diagnosis—-
is based on ocular examination and fluorescein dye testing. If needed, specific examination of the interior of the eye and cytology can also aid in the diagnosis. Other tests, such as a Schirmer tear test, are performed to rule out additional or contributory eye diseases.
Treatment —-
involves elimination of the cause, along with specific treatment for the ulceration and inflammation. Underlying eye problems, such as keratoconjunctivitis, entropion, or ectropion, should be treated appropriately. Treatment of the ulcer may include topical antibiotics to prevent infection, topical atropine to control pain, specific medications to control viral infections, and if indicated, specific medications to prevent collagen breakdown. Animals may be placed on systemic non-steroidal anti-inflammatory (NSAIDs) medications such as aspirin or banamine.
Some ulcers are treated with protective contact lenses. Others may require surgery to trim (debride) the ulcer edges. Additional surgical procedures include punctuate keratotomy, conjunctival flaps, and flaps created from the nictitans. Eyes should be rechecked at approximately 3-day intervals; those with deep ulcers should be rechecked daily until satisfactory healing is observed.
The prognosis —–
for ulcerative keratitis depends on the underlying cause, the severity of the ulceration, the type of treatment employed, and response to therapy. Simple, superficial ulcers often heal nicely in approximately 1-2 weeks. Deeper ulcers treated with surgical techniques may require 4-6 weeks to heal; those treated without surgery may take longer or never heal satisfactorily. Refractory ulcers may remain unhealed for months unless treated with surgical techniques. After surgery, healing may occur in 2 weeks, and conjunctival flaps may be left in place for a month or longer. Untreated or incorrectly treated corneal ulcers can progress, resulting in rupture of the cornea and loss of vision. This often results in removal of the globe.
Corneal opacity may cause temporary to permanent eye damage if left untreated. Immediate diagnosis and necessary therapy are crucial for saving the vision of eyes affected with corneal opacity. Here, we report the medicinal management of corneal opacity in cattle using ciprofloxacin, dexamethasone, prednisolone and vitamin A.
Medical management:———
After careful examination, medical therapy is resorted to. The animal is treated with topical instillation of ciprofloxacin and dexamethasone eye drops , for 14 days, subconjunctival administration of prednisolone acetate and dexamethasone at 3 day intervals for 5 times and intramuscular injection of ketoprofen at 1 mg/Kg bwt, daily for 3 days. Available veterinary preparation of vitamin A at 5000 IU/Kg bwt is also administered for 7days through intramuscular injection
Recent cases can be treated by application of an irritant as calomel insufflation, 3 % yellow oxide of mercury twice daily. The condition can be treated also by either cortisone eye ointment, providing that there is no corneal injury, or by subconjunctival injection of cortisone solution. In some instances opacity can be touched with silver nitrate sticks for few seconds then washing with normal saline solution or distilled water several times.
Eye problems can affect all animal species.——-
• Eye injuries are especially a problem in camels, as their eyes protrude and they gaze on thorny bushes.
• The three most important conditions affecting the eyes of livestock are Pink Eye, Thelazia Eye Worms and Squamous Cell Carcinoma of the eye.
Different types of eye problems may have different causes such as: ———
• Insect bites in the eye
• Ticks attached around the eyelid
• Eye worms
• Foreign bodies in the eye
• Injury to the eye, for instance by thorns or herders’ sticks
• Infectious diseases such as pink eye or camel pox
• Irritating sap from plants
• Snake venom
• Sun induced cancer
• Cataract
The most common signs are: ——-
• Watery or yellowish discharge from the eye
• Partially or totally closed eye
• Swollen eye
• Reddish eye
• Thick, whitish film covering the eye
• Abnormal growths in the eye
Other conditions can cause inflammation of the eye, so in every case, a close inspection of the affected eye is essential.
• Foreign bodies, such as grass seeds and awns can become stuck to the surface of the eye.
• Thorns can be embedded in the cornea.
• Corrosive fluids and saps can inflame the cornea.
• Worms can live in the conjunctival sac.
Eye Worms——–
These worms live in the conjunctival sac (eyelid) of the eye in many species of livestock, in many countries. Cattle, sheep, horses, camels, goats, pigs, dogs, cats, birds, and humans can be affected. The most common species in Kenya is Thelazia rhodesii, which parasitizes cattle and sheep. The worms are up to 2cm long and are thin and white. One or both eyes may be affected.
Mode of Spread——
Various species of fly, in which the worm has part of its life cycle, are responsible for the spread of the worm from one animal to another. The fly has a preference for eye secretions which are ideal for transmission. The fly ingests the larvae which become infective in 2-4 weeks. These larvae are mechanically deposited in teh host’s eye by the fly during feeding. Development of sexually mature worms takes about 1-4 weeks in cattle.
The worm lives under the eyelids, in the conjunctival sac and under the third eyelid. The worm has a rough cuticle (skin) which causes irritation and inflammation to the cornea.
Signs of Eye Worm——-
• Excessive production of tears which may contain pus.
• Avoiding sunlight.
• Inflammation of the thin membrane covering the white of teh eye and the inner surface of the eyelid (Conjunctivitis).
• Cloudiness of the cornea and sometimes ulceration and piercing of the cornea.
• Lack of response to treatment with antibiotics.
Diagnosis-
Close inspection of the eyes will reveal small white worms swimming in the conjunctival fluid. Several animals should be examined as it will not be possible to see worms in every animal. Even if the worms can be seen with the naked eye, a veterinarian should be consulted to confirm their presence.
Recommended Treatment and Control————
• A qualified veterinarian can remove the worms with forceps after instillation of a local anaesthetic solution or
• Using an eye wash containing a local anaesthetic and wash the worms out of the eye. A mixture of 10 ml of 2% local anaesthetic solution with 40-50ml of clean water makes the eye wash. 5-10 ml is put onto the eye and after waiting for about 2 minutes, the worms are washed out of the eye using clean cold water.
• Certain systemic dewormers such as Levamisole at 5 mg/kg under the skin and Ivermectin and Doramectin both at 0.2 mg/kg SC or in the muscle are effective treatments.
• Pour-on forumlations of Ivermectin and Doramectin, delivered on the back of the animal to achieve a dosage of 0.5 mg/kg are also highly effective.
• Treatment is also possible with topical application of Levamisole or topical Ivermectin. Bother are given as a 1% aqueous solution directly into the eye. If the eye discharge is cloudy or white it may be advisable to put an antibiotic ointment into the eye following removal of the worm or following the administration of dewormers.
Squamous Cell Carcinoma———–
Ocular Squamous Cell Carcinoma (Cancer Eye) is the most common tumour of cattle. It is common in various European breeds /especially Friesian/Holsteins, and Ayrshires.
• Zebu cattle are rarely affected.
• When it occurs it results in significant economic loss due to condemnation at slaughter and a shortened productive life.
Cause
Several factors play a part in causing Squamous Cell Carcinoma, including exposure to sunlight, eyelid pigmentation, genetic predisposition, nutrition and perhaps viral involvement. Ultraviolet radiation and a high plane of nutrition are important factors as are whether the eyelids are pigmented or not. The latter is highly inheritable.
Signs
• The lesionsbegin as non-cancerous, smooth, white growths on the eyeball surfaces. These may progress to a papilloma (a small solid benign tumour with a clear-cut border that projects above the surrounding tissue) and then to the cancerous squamous cell carcinoma. Sometimes it goes directly to the cancer stage.
• The eyelids, eyeball surface (third eyelid) and the point where the cornea meets the ‘white’ of the eye all may be affected and the lesions may be ulcerative.
• Both eyes may be affected at the same time. At this early stage an unexpected improvement or cure may occur in a large number of animals. But the tumour may progress and become quite large and cauliflower-like.
• There is a discharge from the eye which may trickle down the face. The tumour may be large without invading the globe but later invasion into the globe and orbit and spread to local lymph nodes may occur.
• The whole eye may be destroyed accompanied by massive local swelling. At this stage no treatment is possible.
Treatment and Control
• Early treatment is usually successful, either by the surgical removal of the tumour itself, or, if this is not possible, by surgical removal of the eye.
• Well equipped veterinarians may have other treatment options such as cryotherapy (a technique that uses an extremely cold liquid or instrument to freeye and destroy abnormal cells), hyperthermia (including extreme body temperature), radiation therapy and immunotherapy.
• But the most important factor in control is early treatment, preceeded by constant, close observation,
Eye Symptoms as Signs of Other Diseases——–
• Cloudy, whitish, milky blue eyes and shedding of tears: See East Coast Fever
• Shedding of tears: See Rhinotracheitis
• Excessive tears: See Mucosal Disease and Heartwater
• Watery discharge and cloudy eyes: See Trypanasomiasis
• Excessive tears which pay contain pus: Inflammation of the thin membrane covering the white of the eye and the inner surface of the eyelid; Cloudiness of the cornea and sometimes ulceration and piercing of the cornea:
Reference-on request
