VETT 132: Week 3
Describe the conjunctiva and know where this is located . . .
A thin, transparent membrane that covers the front portion of the eyeball and lines the interior surface of the eyelids.
What are the general categories of eyelid / adnexa abnormalities?
Abnormalities of the eyelids and adnexa are divided arbitrarily into categories that denote general etiologic considerations, including congenital, acquired, structural/conformational, inflammatory, and neoplastic conditions; category overlap is common.
Where are the meibomian glands (also called tarsal glands) located? Where do the ducts open?
Along the margin of each eyelid.
Distichiasis / ectopic cilia
An eyelash that arises from an abnormal location on the eyelid or grows in an abnormal direction.
What are some things that can be detected when evaluating the conjunctiva?
Blood vessels and mucous membrane color
Ectropion
Eversion of the eyelid
Epiphora
Excessive watering of the eye
What are the indications for performing this test?
Eye redness, mucoid/purulent ocular discharge, pigmentary keratitis, monitoring treatment of any animal with known keratoconjunctivitis sicca (dry eye), and monitoring dogs being treated with medications that may decrease tear production (sulfonamides, etodolac, etc.).
Palpebra
Eyelid
Why are eyelids somewhat resistant to infection and tend to heal rapidly after trauma?
Eyelids are highly vascularized, therefore they are fairly resistant to microbial infection and have the property of healing rapidly after suffering trauma, but may enlarge considerably from transvascular exudation of fluid into lid tissue when irritated.
Describe the problems that may occur with conjunctival foreign bodies . . .
Induce conjunctival irritation and inflammation, and ulceration of the ventronasal cornea.
Conjunctivitis
Inflammation of the conjunctiva
Blepharitis
Inflammation of the eyelid
Entropion
Inversion of the eyelid
What is the most common eyelid neoplasm of dogs?
Meibomian (sebaceous) adenoma. No.
What test is used to measure tear production? What part of the tear film does this test measure?
Schirmer tear test. The aqueous tear film.
List and describe the 3 types of ocular discharge and the causes of each . . .
Serous (viral or allergic), mucoid to mucopurulent (KCS), and purulent (bacterial).
Blepharospasm
Spasm of the eyelid
What is the most common eyelid neoplasm of cats? Is this a malignant neoplasm?
Squamous cell carcinoma. Yes.
Chemosis
Swelling of the conjunctiva
Bulbar conjunctiva
That part of the conjunctiva which covers the outer surface of the eye.
Palpebral conjunctiva
The conjunctiva lining the eyelid
What are the extraocular structures?
The conjunctiva, the eyelids, the tear-production and drainage system, and the muscles that move and position the eyeballs.
In addition to applying eye medications on the sclera, where would be a good area to instill eye drops / ointments?
The conjunctival sac
Lacrimation
The flow of tears
Medial canthus
The inner corner of the eye
List the 3 layers of the tear film, where they are located, and where each is produced?
The inner mucous layer comes from cells in the conjunctiva, the middle tear layer comes from the lacrimal glands and the accessory lacrimal glands of the third eyelids, and the outer oily layer comes from the meibomian glands.
Lacrimal puncta
The opening that allows tears to exit the lacrimal ducts.
Lateral canthus
The outer corner of the eye
What is the conjunctival sac?
The space between the bulbar and palpebral portions of the conjunctiva.
What structures compose the lacrimal apparatus?
The structures that produce and secrete tears and the structures that drain them away from the surface of the eye. This includes the lacrimal gland, secretory ducts, lacrimal puncta, upper canaliculus, lower canaliculus, lacrimal sac, nasal cavity, and nasolacrimal duct.
Nasolacrimal duct
The tear ducts that connect the lacrimal puncta and the nostrils.
Describe the nictitating membrane. What is another name for this structure?
The third eyelid
What are the functions of tears?
They moisten and protect the eyes.
Cherry eye
This defect of the nicitating membrane causes the gland to prolapse and protrude from the eye as a red fleshy mass.
What can occur if physical or functional abnormalities of the eyelids or adnexal structures exist?
This may result in abnormalities of the cornea and subsequently vision.
