Eyelids and the Third Eyelid Flashcards
Palpebral
refers to eyelid
Palpebral fissure
eyelid opening
Blepharo
refers to eyelids (blepharospasm, blepharoedema, blepharitis)
Canthus
where upper & lower eyelids meet: medial & lateral canthus
Cilia
eyelashes
Meibomian glands
tarsal glands = lipid secreting glands lining eyelid margins
proper conformation of the eyelid
The eyelids should conform to and rest against the cornea with the mucous membrane lining (palpebral conjunctiva) in contact with the cornea.
function of the eyelid
protect cornea, spread tear film, and reduce light stimulation for sleep; Any abnormality in this relationship may cause corneal irritation, pain, loss of corneal transparency and conjunctival inflammation.
What holds the eyelids open
The eyelids are held open by both sympathetic tone and by the levator muscle (Crn III).
What holds the eyelids shut?
They are closed by the obicularis oculi m. which encircles the eyelids and is innervated by Crn VII
Inability to close the eyelid is a dysfunction of what nerve?
CN VII or loss of sympathetic tone
sensory innervation to the eye
Sensory innervation to the eyelids is from Crn V (trigeminal n).
Blepharhospasm
the involuntary spasm or squinting of the eyelids caused by pain from disorders such as cilia contacting the cornea, dry eye, conjunctivitis, corneal ulcer, uveitis or glaucoma.
Blepharoedema
is swelling of the lids and is usually associated with an allergic reaction such as vaccine reaction or bee sting.
Treatment of belpharoedema
It can be treated with topical and/or systemic antihistamines or anti-inflammatory drugs based on the underlying cause.
Dermoid:
Skin and hair that develop in an abnormal place in the body is a dermoid. They commonly affect the cornea, but in some cases only the eyelid and/conjunctiva are
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affected. The hairs cause corneal irritation and may preclude normal eyelid closure.
Treatment of a demoid
They should be surgically removed with careful reconstruction of the affected eyelid margin.
Eyelind agenesis
This congenital defect usually affects the upper lateral eyelids in the cat, and is occasionally seen in the lower eyelids of dogs.
treatment for eyelid agenisis
Corrective, reconstructive surgery is indicated.
Ophthalmia Neonatorum (neonatal ophthalmia)
the result of an infection occurring prior to the natural lid opening at 10-14 days causing swelling behind the eyelids and purulent exudate.
Treatment for opthalmia neonatorum
The eyelids need to be gently opened, irrigated and treated topically with antibiotic ophthalmic ointment. The cornea needs to be kept moist.
Entropion
the rolling inward of the eyelid causing hair to rub on the cornea. It is a hereditary problem in many dog breeds and may have a later age of onset.
Genetic predisposition to entropion?
Brachycephalic cats and dogs generally have medial entropion and trichiasis.
Entropion is often seen in premature foals, lambs and Shar Pei puppies and alpacas.
Treatment for entropion
Eyelid tacking is a temporary solution to this problem. Vertical mattress sutures using
5-0 nylon or prolene can be left in place for several weeks and may not require further treatment. The knots should be placed distal from the eyelid to avoid corneal trauma.
Acquired entropion causes
may be the result of trauma (cicatricial/scarring) or chronic pain. In cats it is commonly seen after chronic conjunctivitis or keratitis resulting in enophthalmos and secondary entropion.
Treatment of acquired entropion
If the entropion does not resolve with topical anesthetic (spastic entropion), surgical correction is needed using the Hotz-Celsus procedure.
Ectropion
outward rolling of the eyelid and is considered “normal” in some breeds such as the Saint Bernard, Newfoundland, and Bloodhound.
Complications of ectropion
Exposure of the conjunctiva occurs with ectropion and causes irritation and chronic ocular discharge.
Distichiasis
hair (cilia) emerging from the meibomian gland openings (which normally secrete lipid tear film). Soft hairs directed away from the patient may not be a clinical problem, however hairs that are more rigid and directed toward the cornea are painful, cause corneal damage, and delay healing of corneal ulcers.
Breeds predisposed to distichiasis
Breeds commonly affected are the Shih Tzu, American Cocker Spaniel, Pit Bull Terrier and Poodle.
Treatment of distichiasis
These are removed by electroepilation or cryosurgery if multiple distichia are present. (Referral procedure)
Ectopic cilia
hairs that grow under the eyelid from the base of the meibomian gland through the conjunctiva and are directed toward the cornea. This is a very painful condition and hairs may be difficult to find.
Ulcers associated with ectopic cilia
Ulcers created from these hairs are located just below the cilia (usually 12 o’clock) and can quickly progress.
Treatment of ectopic cilia
Surgical removal (referral procedure) is indicated as soon as possible. Temporary protection of the cornea by a contact lens should be considered until referral is possible. (Referral procedure)
Trichiasis
the abnormal direction of growth of hair from a normal site. At the medial canthus they act as a wick and pull tears onto the face and are commonly the causes of tear staining seen in many breeds of dogs.
Consequence of trichiasis
The chronic irritation to the cornea may also cause corneal pigmentation that can progress to reduced vision.
Considerations regarding the repair of eyelid lacerations
minimal or no debridement, start at the lid margin
eyelid tumors in the dog are usually ___
benign
eyelid tumors in the cat are ___
less common but more likely malignant
wart like growths (tumors) on the eyelid are often ___ on the dog?
Meibomian gland adenomas, epitheliomas and papillomas are frequently seen as a wart like growth on the lid margin of dogs and may cause corneal irritation and mucoid discharge. Eyelid
Eyelid melanomas
Eyelid melanomas in the dog tend to be benign, and histiocytomas may be self-limiting.
when performing tumor removals on cats and dogs, how much are you able to remove?
Surgical removal of the tumor with up to 1/3 of the lid margin can be removed in dogs, and 1/4th in cats, by V to I plasty.
blepharitis
is inflammation of the eyelids and is similar to dermatitis elsewhere on the body.
Etiology of blepharitis
The inciting factor must be identified as many of these patients are exhibiting an allergic manifestation, often food allergies.
Diagnostic plan for blepharitis
Cytology and biopsy to identify and treat bacteria and malassezia with appropriate antimicrobials, fatty acids, anti-histamines and exclusion diet are indicated.
the third eyelid contains what other structures
It contains a lacrimal gland (gland of the nictitans) at the base of the ‘T’ cartilage (producing 25-30% aqueous tear production) and lymphoid tissue.
What keeps the third eyelid in the retracted position
sympathetic tone; It is elevated in most species by passive motion as the globe is retracted by the retractor bulbi muscle.
Functions of the third eyelid
The 3rd eyelid functions to produce part of the tear film, sweep the tears across the cornea and aid in removing debris.
Elevations in the third eyelid may be caused by what?
The third eyelid may be elevated due to enophthalmos (Horner’s syndrome, loss of orbital fat), microphthalmia, phthisis bulbi, neurologic disease, pain, mass effect, glaucoma or tetanus
Cherry eye
The third eyelid may be elevated due to enophthalmos (Horner’s syndrome, loss of orbital fat), microphthalmia, phthisis bulbi, neurologic disease, pain, mass effect, glaucoma or tetanus
Common presentation of cherry eye
It is usually bilateral even though it may present initially unilaterally.
Treatment for cherry eye
Because of its role in tear production, it is contraindicated to remove the gland unless there is a tumor present. The ‘Morgan pocket technique’ is widely used
-Securing the gland to the inferior rectus is done as referral procedure.
Follicular conjunctivitis - age and defnition
specific condition seen in dogs under 24 months old. It is considered an immune or possibly allergic condition that the patient will outgrow.
follicular conjunctivitis presentation
Hyperplastic lymphoid follicles are seen behind the 3rd eyelid with conjunctival hyperemia and ocular discharge.
Treatment of follicular conjunctivitis
A topical antibiotic/steroid (BNP-HC or NP Dex) will alleviate clinical signs and will need to be continued at the lowest possible interval until the patient “outgrows” the problem.
consideration regarding follicular conjunctivitis
Corneal ulceration and all other causes of conjunctivitis must be ruled out before making this diagnosis or using steroids. Other treatment options are hypoallergenic diet, topical cyclosporine and mast cells blockers.
Scrolled cartilage - definition and treatment
defect of the T-cartilage that causes the 3rd eyelid to bend, causing irritation and discharge that requires surgical correction. This is a referral procedure to remove the distorted portions of the cartilage.
Most common neoplasia of the eyelid
SSC; but others: Adenoma, LSA (lymphosarcoma), adenocarcinoma, SCC (squamous cell carcinoma), melanoma, and hemangiosarcoma have been reported.
