Degenerative conditions of the

eye`s

Asteroid hyalosis

Asteroid hyalosis is a degenerative condition of the eye involving

small white opacities in the vitreous humor.

The cause of asteroid hyalosis is associated with diabetes mellitus,

hypertension, hypercholesterolemia, and tumors of the ciliary body.

In dogs, asteroid hyalosis is considered to be an age related change.

Asteroid hyalosis does not usually severely affect vision

Vitrectomy may occasionally be indicated for therapeutic purposes.

Vogt–Koyanagi–Harada syndrome

Vogt–Koyanagi–Harada syndrome - VKH syndrome - is an immune-mediated disease. The mechanism of the disease is thought to be T helper cell mediated autoimmune attack of melanocytes in the skin and uvea of dogs and humans, and in the central nervous system and inner ear of humans.

VKH involves various melanocyte-containing organs, characterized by:

→uveitis (inflammation of the inside of the eye),

→poliosis (whitening of hair),

→vitiligo (loss of pigment in the skin),

→meningitis, although dogs with this syndrome rarely develop meningitis.

In dogs VKH syndrome most commonly affects young animals.

VKH syndrome cause retinal detachment, cataracts, and glaucoma. (Pigment partly disappears from the retinal pigment epithelium and iris. Skin lesions include loss of pigment and hair on the eyelids, nose, and lips.)

Treatment is with immunosuppressive drugs such as prednisone and azathioprine.

Entropion

http://en.wikipedia.org/wiki/File:Canine_entropion.JPG

Entropion is a medical condition in which the eyelid folds inward.

It caused by genetic factors and may be congenital, it can also occur

secondary to pain in the eye, scarring of the eyelid, or nerve

damage.

The condition is usually present by six months of age.

Treatment is a simple surgery in which excess skin of the outer lids

is removed. Prognosis is excellent if surgery is performed before

the cornea is damaged.

Symptoms:

→ redness and pain around the eye

→ sensitivity to light and wind

→ sagging skin around the eye

→ excessive tearing

Exophthalmos

Exophthalmos is a bulging of the eye anteriorly out of the orbit.

If left untreated cause blindness, eyelids failing to close during

sleep leading to corneal dryness and damage. Another possible

complication would be a form of redness called "Superior limbic

keratoconjunctivitis," where the area above the cornea becomes

inflammed as a result of increased friction when blinking. The

process that is causing the displacement of the eye may also

compress the optic nerve or ophthalmic artery leading to

blindness.

Eye proptosis

Eye proptosis is a condition resulting in forward displacement of

the eye from behind by the eyelids. The condition is also known as

eye dislocation and eye luxation.

Replaced eyes have a higher rate keratoconjunctivitis sicca and

keratitis and often require lifelong treatment. If there is severe

damage, the eye is removed in a relatively simple surgery known as

enucleation of the eye.

The prognosis for a replaced eye is determined by the extent of

damage to the cornea and sclera, the presence or absence of a

pupillary light reflex, and the presence of ruptured rectus muscles.

The rectus muscles normally help hold the eye in place and direct

eye movement. Rupture of more than two rectus muscles usually

requires that the eye be removed, because there is usually also

significant blood vessel and nerve damage.