List of five major eye diseases found in animals:- 1. Conjunctivitis 2. Blepharitis 3. Stye 4. Trichiasis 5. Recurrent Ophthalmia.
Contents
Eye Disease # 1. Conjunctivitis:
It may occur as a simple congestion of the membrane or be accompanied by oedema of the tissue with or without secretion varying character.
The following forms of conjunctivitis may be observed:
1. Catarrhal Conjunctivitis and
2. Purulent Conjunctivitis.
1. Catarrhal Conjunctivitis:
Etiology:
Catarrh of the eye generally results from exposure to cold. Mechanical and Chemical influences also produce a certain effect such as foreign bodies (dust, hair etc.), turning in of the eyelashes, smoke of soft coke. Catarrh of the conjunctiva is intimately connected with catarrh of the respiratory organs such as nasal catarrh, distemper etc.
Symptoms:
Pain and twitchings of the eyelids. At early stages, there is a flow of tears. Later it becomes mucus and finally muco-purulent discharge is observed. The conjunctival membrane becomes greatly swollen and injected. Intense itching causing the animal to scratch the affected eyes continually.
2. Purulent Conjunctivitis:
Etiology:
Due to specific infections, organisms develop in the course of some epizootic disease, particularly distemper and a specific form of this disease may occur as an epidemic, the cause of which up to the present time has not been definitely described, but most probable cause may be due to viral infection.
Symptoms:
Considerable swelling of the membrane. The membrane is sometimes spotted red by haemorrhage and photophobia. The animal constantly winks and closes the eyes. Mucopurulent discharge which agglutinates the eyelids, particularly during night when the animal is asleep. There is great itching and irritation causing the animal to rub the eyes.
Treatment:
If due to foreign bodies or caused by trichiasis or entiopion, it is necessary to remove the foreign body. Clean the eyes thoroughly with saline water. Apply Chloramphenicol or Gentamycin ointment twice or three times daily. In catarrhal conjunctivitis, astringents such as Silver nitrate solution is quite useful.
Eye Disease # 2. Blepharitis:
An inflammation of the lid is known as Blepharitis.
There are two types:
1. Superficial and
2. Ulcerative.
The superficial type is manifested by the presence of redness and, swelling together with the formation of crusts which usually occur above the lashes and frequently cause them to fall out on slight friction. Hair follicles are not involved and the lashes grow again by proper treatment.
In the ulcerative type, the above symptoms are present but are more severe together with ulceration which occurs beneath the crust. This ulceration invades the hair follicles and when the lashes are once lost, they fail to grow again. It is often due to infection.
Some itching is often present and rubbing the lids tends to create a fresh focus for the growth of the organisms. The lids are heavy and partly closed and the matting together of the lashes with crusts and the secretion makes the animal look as though it is suffering from some severe constitutional disease.
Treatment:
This should be directed against the cause. If conjunctivitis or other diseases of adjacent structures exist, they should be met by appropriate therapeutic measure. In mild cases, soften the crust with vaseline and after this has remained for several hours, wash it off with mild alkaline solution, remove the crust that may remain and apply Gentamycin or Chloramphenicol ointment.
Eye Disease # 3. Stye:
A localised infection about a hair follicle resulting in suppuration. A stye may occur independent of blepharitis though they often occur together. Pain, localised tenderness and swelling are the prominent symptoms. In some cases, a profuse oedema of whole lid occurs. Styes often appear in succession, two or more may occur in the same time. At the late stage of suppuration, they tend to point and rupture of their own accord.
Treatment:
Same as that of Blepharitis, when the stye points, it is better to open it with a small sharp pointed instrument and express the contents.
Eye Disease # 4. Trichiasis:
This is an abnormal position of the eyelashes. They grow inward or backward towards the globe instead of outward. It is often caused by contraction of the inner surface of the eyelid from diseases of the conjunctiva. It produces great irritation of the cornea by constantly scratching it in the act of winking. If the irritation continues, inflammation and opacity of the cornea may follow.
Treatment:
If only a few lashes turn inward, they may be extracted with a pair of forceps. This operation must be repeated at regular intervals. If the condition is general and accompanied with entropion—as it often is—one of the several operations may be performed.
Eye Disease # 5. Recurrent Ophthalmia:
It is commonly known as Moon blindness and periodic ophthalmia. It has no relation with Moon’s changes but, being subject to periodic attacks, it has been known by the latter name. It seems to be particularly confined to horse. It is a disease affecting all the structures of the eye but characterised chiefly by Iritis. An initial attack may get well but in the course of 80 to 90 days, it may recur and if these recurrences continue, the eye may be eventually lost.
Etiology:
The true cause of the disease is not known. Robert Koch found cocci in the aqueous humor which, when injected into the normal eye of a horse, produces a typical ophthalmia with the loss of the eye. Some presume that Lepto- spiral infection may be the cause of periodic ophthalmia in horse but no positive proof is available. Other investigators have found various organisms but none has been definitely determined to be the specific cause. The principal predisposing cause is heredity.
Symptoms:
The disease first shows itself by acute inflammation, weeping, photophobia, swelling of the eyelids, slight turbidities of the aqueous humor and of cornea. After the acute symptoms subside, the turbidity of the anterior chamber becomes more marked. Exudates are thrown from the Iris and adjacent bodies and are deposited in the dependent portion of the anterior chamber.
The cornea becomes hazy from the presence of this material on its posterior surface and from cellular infiltration. If the inflammation is not too severe, it ceases in 12 to 15 days and the eyes resume normal appearance. The course of the trouble varies in intensity in different cases and does not always show all the features depicted above, and almost constant sequel of the disease—irrespective of acuteness of the attack—is adhesion of the iris to the lens.
Repeated attacks of the affection cause lesions of the lens, choroid and retina and eventually atrophy of the eye accompanied by deformity of the Iris. The two eyes are usually affected alternately, but sometimes both are affected simultaneously.
Treatment:
Seems to be of little value in most cases. Local conditions should be met by proper therapeutic measures together with the observance of proper feeding and hygienic conditions. Good results have been claimed by the administration internally of calomel and Pot. Iodide. The latter is repeated daily until iodism appears. Locally, chief reliance is placed on the instillation of atrophine to prevent synechia and closure of the pupil.