◊ 5-Conjunctiva ◊
CONJUNCTIVAL AFFECTIONS
I-CONGENITAL ANOMALIES OF THE CONJUNCTIVA: -
1-Dermoids: -
Definition:
It is a congenital tumour may involve the conjunctiva alone, eyelids or cornea. The tumour mass is dark brown to black in color and covered with a variable number of long hairs. Surgical excision of the mass is indicated. Conjunctival wound can be left unsutured in small defects but should be sutured if extensive.
2- Ectopic cilia: -
Definition:
It is one hair or clusters of hairs that originate at the conjunctiva. It is usually developed several months to several years after birth. Ectopic cilia may be congenitally misdirected hair follicle that produces hairs.
Signs:
1-Epiphora, blepharospasm and mucoid discharge are evident.
2-A small dark red and slightly raised part of the conjunctiva may surround the cilia.
Treatment:
Electroepilation with destruction of the hair follicles
II-ACQUIRED DISEASES OF THE CONJUNCTIVA: -
1-Conjunctivitis: -
Definition:
It is inflammation of the conjunctiva.
General signs of conjunctivitis:
1-Active hyperaemia; vascular injection of the conjunctival blood vessels
2-Chemosis; oedema of the conjunctiva. Thickening of the conjunctiva may become so severe that bulbar conjunctiva extends over the cornea apd beyond the edges of the eyelids.
3- Ocular discharge; usually starts as serous and becomes mucopurulent and purulent
4- Follicles; it is normally present on the bulbar surface of the third eyelid. The development of these follicles on the outer surface of the nictitating membrane or bulbar and palpebral conjunctivae, in addition to its proliferation at the normal sites is considered a diseased condition.
5-Pain; may be mild or severe depending on the cause. Blepharospasm or spastic entropion may result.
Etiology:
1-Mechanical causes: -
A-Exogenous irritative factors such as; foreign bodies, dust, sand, owns, husks, dried leafs, hair, eyelash, smoke, bright sunlight and low humidity. :
B-Endogenous factors such as; deficiency of precorneal tear film, entropion, ectropion, distichiasis, trichiasis, ectopic cilia, prominent nasal folds, lagophthalmos, exophthalmos and eyelid tumors.
2-Chemical causes: -
A-High percentage of ammonia in stable air due to bad ventilation
B-Gases such as sulpher fumes and formaline vapor in cases of stable disinfection.
C-Eye lotions or ointments applied to the eye in higher concentration.
D-Acids and alkalies burns: Alkalies have a more destructive effect than acids. Acids causes precipitation of protein which act as a barrier against further penetration and destruction.
E-Chalky materials used to beautify the animal coats during exhiption.
3-Traumatic causes: -
A slight injury such as cat scratches and abrasions may act as a primary cause or may provide a point of entrance of microorganism.
4-Infection: -
May be restricted to the eye or part of a systemic disease.
A-Bacterial B-Viral C-Mycotic D-Mycoplasma E-Chlamydia F-Rickettsia.
5-Parasitic causes: -
A-Genus thelazia: Reported in all domestic animals. Usually cause mild conjunctivitis and epiphora.
B-Onchocerca cervical is in horses C- Habronima larvae in horses
D-Face flies in horses and cattle. E-Demodectic mange in dogs.
6-Allergic causes: -
A- Pollen grains B-Type and quality of hay in large animals
C-Conjunctival sensitivity against special antibiotics as penicillin or neomycin.
7-Systemic diseases: -
Conjunctivitis occurs in the course of some infectious diseases such as canine distemper in dogs; feline catarrh in cat; malignant catarrhal fever, infectious bovine rhinotracheitis and infectious
bovine keratoconjunctivitis in cattle; equine influenza in horses; or disease in sheep and swine fever in pigs.
8-Difficiency causes: -
Vitamin A difficiency causes degeneration of lid conju'nctival epithelium.
9-lodism: -
In cases of treatment of actinomycosis by using potassium iodide.
10-Old age and debility: -
Classification:
Conjunctivitis is classified according to the clinical symptoms into;
A-Catarrhal conjunctivitis B-Purulent conjunctivitis. C-Parenchymatous conjunctivitis
D-Follicular conjunctivitis. E-Ophthalmia neonatorium.
A-Catarrhal conjunctivitis: -
Definition:
It is catarrhal inflammation of the conjunctiva, which characterized by increased tear and mucous production
Signs:
1-Increased flow of tears (epiphora) that soon starts to run down the face of the animal. In the earlier stages, these are watery, clear and saline in character. Next the discharge becomes mixed with mucoid secretion and becomes sticky, thick and gelatinous
2-Thickening and edema of the conjunctiva (Chemosis)
3-The eyelids are inflammed and swollen. The edges may be gummed together with exudates.
4-Blepharospasm and photophobia
Treatment:
1-Thorough examination and elimination of the cause if present
2-Washing the eyeball and conjunctival sac for removal of discharges using worm normal saline solution or boric acid solution 2%.
3-Antibiotics; the drugs are chosen for their effectiveness on the tear film and no need for penetration of epithelium.
4-Corticosteroids (Anti-inflammatory drugs).
5-Antihistaminics (Anti-allergic drugs).
B- Purulent conjunctivitis: -
It is purulent inflammation of the conjunctiva. The main cause is bacterial infection, but other causes of conjunctivitis cannot be neglected. Purulent conjunctivitis can be artificially induced by mallein test and tuberculine test.
Symptoms:
1-The eyelids are swollen, edematous and sticked together.
2-The conjunctiva is red, swollen and edematous.
3-The discharge at first is like meat-juice and consists of serium, fibrin, inflammatory cells and flacks of pus. Later on becomes purely purulent and comes continuously from the medial canthus of the eyeball.
Treatment:
1-Elimination of the cause
2-Thorough washing of the eyeball with cleansing solution. Make sure special tests have been completed (culture and Schirmer tests) before irrigation with cleansing solutions.
3-Antibiotic Ointment is applied 2-4 times daily or solutions instilled at least 4 times for 7 days. Broad spectrum antibiotic is used. Combinations of different antibiotics are more useful otherwise sensitivity test is performed first. Treat the least affected eye first and steralized eye droper
is used for instillation of drugs.
4-Anti-inflammatory; corticosteroids can be used.
C-Parenchymatous conjunctivitis:
Definition:
It is inflammation of the deeper layers of the conjunctiva. It is mostly considered to be a higher degree of simple catarrhal conjunctivitis.
Symptoms:
1-Severe swelling of the conjunctiva specially the bulbar one (chemosis) The bulbar conjunctiva extends over the cornea covering the limbus and the palpebral conjunctiva extends beyond the eyelid margin.
2- Serous or mucoid discharge
Treatment:
1-The same treatment for catarrhal conjunctivitis
2-Wormcompresses applied to the closed eye will reduce the swelling of the conjunctiva dramatically.
D-Follicular conjunctivitis: -
This type of conjunctivitis is characterized by presence of hypertrophied lymphoid follicles at the bulbar surface of the third eyelid and perhaps on the palpebral surface and on the palpebral conjunctiva of the upper and lower eyelids. Lymphoid follicles are located normally on the bulbar surface of the nictitating membrane in all domestic animals. The follicles are essential for the mechanism of controlling ocular infection. Any chronic irritation or immunological stimulant will stimulate them to become hyperplastic. A new follicles will develop anywhere on the conjunctiva. After the follicles have been formed they will sustain themselves even if the initiating cause disappeared.
Causes:
1-Prolonged ocular irritation specially mechanical causes either exogenous (dust, winds, etc ...) or endogenous (entropion, ectropion, distichiasis, etc ...).
2-Immunological stimulus includes pollen grains and migrating parasites.
3-Previous infection as in cases of bacterial conjunctivitis since these lymphoid follicles are centers of antibody production. In 25% of 'cases of follicular conjunctivitis in dogs, inclusion bodies like that isolated in cases of trachoma in human beings was discovered. This indicates that viral infection may be incorporated in such disease.
Symptom:
1-Persistent grayish mucoid discharge at the medial canthus of the eye.
2-Examination of the bulbar surface of the nictitating membrane revealed presence of a red, roughened appearance of the hyperplastic lymphoid follicles. The follicles may present elsewhere in all conjunctival surfaces.
Treatment:
1-Removal of any predisposing causes.
2-Mild cases can be treated by antibiotic-steroid therapy.
3-Removal of the follicles from the bulbar surface of the nictitating membrane by one of the following methods;
a-Debriding (scraping or curetting) of the follicles with a dull blade curette, end of the scalpel handle or any blunt instrument. Then apply zinc sulphate 1/2% solution as astringent. This treatment is followed by 7-10 days topical corticosteroid antibiotic ophthalmic ointment.
b-Cauterization of the follicles with copper sulphate crystals or silver nitrate sticks. Grasp the third eyelid with a mosquito artery forceps, evert the membrane on the forceps and start cauterization. Scraping sometimes is recommended before cauterization. Flush the third eyelid and the eyeball with normal saline and apply a liberal amount of ophthalmic ointment between the third eyelid and the eyeball. Copper sulphate causes severe corneal damage therefore do not allow it to touch the cornea and be sure to flush adequately after cauterization. Antibiotic-cortizone ophthalmic preparations are used for 5 days.
4- Individual follicles elsewhere in the conjunctiva don't scrape it or use cauterization, as it will result in an adverse reaction. Try to use electrocauterization of each follicle or remove each one with scissors.
N.B.:
Surgical excision of the third-eyelid is not recommended, as a treatment for follicular conjunctivitis as the disease, is much more distressing to the owner more than to the patient and therefore the treatment is optional. In addition, complications from third eyelid excision add to much stress on the animal than do follicular conjunctivitis itself.
E-Ophthalmia neonatorium: -
Definition:
Acute purulent conjunctivitis of newly born puppies and kittens before eyelids separation takes place. The purulent discharge builds up beneath the lids causing them to swell and may extrude at the medial canthus of the eye.
Treatment:
1-Seperate the lids with blunt tenotomy scissors
2-Wash the eyeball with cleansing solutio
3-Apply broad-spectrum antibiotics
2-Conjunctival wounds and laceration: -
Causes:
1-Cat scratches, bite wound, and fighting in small animals
2- Blows on the eye or penetrating foreign bodies or gunshot wound in all animals.
Symptoms:
1-Bloody tears 2-Blepharospasm 3-Protrusion of the third eyelid.
4-Presence of wound or laceration of the conjunctiva with swelling and edema of the wound edges
Treatment:
The conjunctiva heals rapidly if uncomplicated by infection. Torn bulbar conjunctiva adheres very quickly to the episcleral tissues within few hours and complete healing takes place within 24 hours.
1-Lacerations of the bulbar conjunctiva heals quickly and need to be sutured only if extensive. Use 6/0 or 7/0 absorbable suture materials with eyeless needle.
2-Lacerations at the fornices: Clean the wound and remove any protruding periorbital fat through the wound before suturing.
3-Lacerations at the palpebral conjunctiva heal without surgical interferences.
In all cases antibiotic ointment is applied to prevent infection.
3-Subconjunctival hemorrhage: -
Subconjunctival haemorrhage usually follows a blunt trauma to the eyeball with or without proptosis and is due to rupture of Subconjunctival (episcleral) blood vessels. Sometimes the blood is migrating anteriorly from periorbital haemorrhage. The extravasated blood is present under the distended bulbar conjunctiva. In some cases subconjunctival haemorrhage may- be due to some systemic bleeding disorder.
Treatment:
1- If the bleeding still present, apply epinephrine 1-2% topically
2-When hemorrhage has stopped; it will recover in most cases without treatment. To hasten recovery corticosteroids may be injected subconjunctivaly.
4-Conjunctival tumors: -
Conjunctival tumors are most common in cattle and horses and rare in other domestic animals. The most common tumour in cattle, horse and cats is squamous cell carcinoma. In dogs haernnangioma, papilloma and histocytorna are the most common types.
Treatment:
Tumors present at the bulbar conjunctiva can be easily excised due to its loose attachment to the sclera and the wound can be closed with fine catgut. Tumour;; present at the palpebral conjunctiva need careful dissection and wound closure.