Animal eyes – Aloe Vera in Veterinary Practice
Animal eyes – eyelids and lashes
Animal eyes – Eyelids and lashes in Animals have 3 eyelids – two external ones like ours – and a third inner lid called the nictatating membrane, which originates from the side of the eye nearest the nose (medial canthus).
The function of the eyelid is to spread the tears over the whole surface of the eye. Foreign bodies, such as grass seeds, frequently get stuck under the eyelid, and under the third lid in particular.
Tears are secreted by lacrimal glands.
The tears keep the eye surface moist and contain a type of antibiotic to help fight off infection.
The tears are collected by a tear duct located at the inner corner of the eye.
The duct then runs down the inside of the nose as the naso-lacrimat duct and discharges on the floor of the nostril near its entrance.
In some animals, like the horse, it is quite easy to see this inside and on the floor of the nostrils.
Too much production of tears, or if the ducts are blocked, leads to tears overflowing the eyelids and running down the face.
This will stain the hair and bum the skin – a condition frequently seen in white Poodles.
A thin mucous membrane composed of epithelial cells that covers the inside of the eyelids including the third eyelid.
It also covers the white of the animal eyes (sclera).
A relatively thick, resilient, transparent layer that comprises the onterior portion of the eyeball.
It should be clear as glass.
It is very prone to injury, infection and ulcers.
The white edge of the eye that extends alt round it.
It is a thick connective tissue that retains the eye’s shape and gives it strength.
Ciliary body and Suspensory ligament.
These are extensions of the sclera.
They support the lens and alter its shape so that the eye can focus.
A thin membrane that lies between the sclera and the retina.
A thin, tight-sensitive membrane lying on the inner surface of the choroid composed of a pigmented layer and a nerve containing layer.
The light-sensitive cells known as rods and cones are found in the pigmented layer.
The cones are responsible for acute vision and to distinguish colours.
The rods allow vision in dim light and contain the pigment rhodopsin that is bleached in the light and regenerated in the dark.
The images seen by the retina are passed through the nerve layer to the optic nerve and thence to the brain.
- Anterior chamber – contains aqueous humour.
- Posterior chamber – contains vitreous humour.
Focuses the images seen on the retina and is the site of cataracts.
The dark hole seen through the lens in the middle of the iris.