eye worm(redirected from eye worms)
the organ of vision. In the embryo the eye develops as a direct extension of the brain, and thus is a very delicate organ. To protect the eye the bones of the skull are shaped so that an orbital cavity protects the dorsal aspect of each eyeball. In addition, the conjunctival sac covers the front of the eyeball and lines the upper and lower eyelids. Tears from the lacrimal duct constantly wash the eye to remove foreign objects, and the lids and eyelashes aid in protecting the front of the eye.
The eyeball has three coats. The cornea is the clear transparent layer on the front of the eyeball. It is a continuation of the sclera (the white of the eye), the tough outer coat that helps protect the delicate mechanism of the eye. The choroid is the middle layer and contains blood vessels. The third layer, the retina, contains rods and cones, which are specialized cells that are sensitive to light. Behind the cornea and in front of the lens is the iris, the circular pigmented band around the pupil. The iris works much like the diaphragm in a camera, widening or narrowing the pupil to adjust to different light conditions.
The optic nerve, which transmits the nerve impulses from the retina to the visual center of the brain, contains nerve fibers from the many nerve cells in the retina. The small spot where it leaves the retina does not have any light-sensitive cells, and is called the blind spot.
include orbital fascia, ocular muscles, eyelids, tunica conjunctiva, lacrimal apparatus and, in the pig, the orbital ligament.
observed with dehydration in birds, where the eyeball is sunken, particularly in raptors which normally have a prominent, round globe.
a common term for corneal edema. See also blue eye.
common lay term for ocular squamous cell carcinoma.
see cherry eye.
one with a blue iris.
seen in dogs with sunken eyes and loose skin in the eyelids which drop inwards, such as St. Bernards and Newfoundland. Often contributes to entropion.
vestibular nerve lesion will cause the eye on the affected side to deviate downward more than the opposite eye when the head is lifted.
see keratoconjunctivitis sicca.
permanent protrusion of the lower conjunctival sac; thought to be inherited in some breeds of guinea pigs.
term for congenital cataracts in guinea pigs.
eye preservation reflex
see menace reflex.
an eye showing dilation of conjunctival, episcleral or ciliary blood vessels.
includes eye preservation (menace), pupillary light, consensual light reflexes.
see canine teeth.
wall eye, walleye
various medicated solutions used to flush the eye; called also collyria.
one with an iris containing blue and yellow or brown pigment.
eye white percentage
an estimate of the startle response and an indicator of fear in dairy cattle.
white eye syndrome
congenital cataract associated with congenital bluetongue infection in calves.