drraythe's version from 2016-04-29 14:45

intro and anatomy and conditions of nictitans

Question Answer
wut dis?3rd eyelid cartilage eversion
wut dis?3rd eyelid gland prolapse
where does the 3rd eyelid (Nictitans) start from?Originates in the anterior ventromedial orbit
what part of the tears does the gland of the 3rd eyelid make?the aqueous portion (not lipid)
what is the shape of the 3rd eyelid? What are its components?Triangular in shape; covered with conjunctiva, “T-shaped” hyaline cartilage, Gland of the third eyelid (pic: gland circled in red)
function of the 3rd eyelid/ nictitans?Protects the globe, Secretion and distribution of tears, Aid in removal of particulate matter from the eye, The eye’s “windshield wiper”
WHY SHOULD WE NEVER EVER CUT OUT the 3rd eyelid???BC THE GLAND OF IT PRODUCES 30-70% of the tears of the eye! if you cut it out, you can get dry eye!
how would you describe the movement of the 3rd eyelid/how does it move?passive- Its movement depends on factors like: Orbital tone, Orbital fat, Hydration status. Exception - CATS (Believed to have some smooth muscle and sympathetic innervation to their 3rd eyelid movement)
where is the gland of the 3rd eyelid? how does it work/what does it do?Encompasses base of cartilage of 3rd eyelid, and Seromucous secretions exit through ducts open in the posterior aspect of the TE(third eyelid) between lymphoid follicles. *Contributes a SIGNIFICANT portion of basal tear production* (30%-70%)
what is the ONLY reason to cut out the 3rd eyelid?cancer
what are 4 Primary diseases of the 3rd eyelid?(1) Gland Prolapse (2) Elevated 3rd eyelids (3) Malformed (“scrolled”) cartilage (4) Neoplasia
3rd Eyelid Gland Prolapse...aka? WHO does this affect most? age? breeds?aka “Cherry Eye” Usually in dogs, < 1year, predisposed breeds are: beagles, cocker spaniels, boston terriers, poodles, brachycephalic breeds
what are two possible proposed causes of 3rd eyelid gland prolapse?(1) Weak fascial attachments to the ventromedial orbit (2) Immune stimulation (recent vx?)
what are the major clinical concerns/implications 3rd Eyelid Gland Prolapse might cause? (3)(1) Conjunctivitis / chronic irritation (2) KCS (2) Cosmetic concerns
what are the treatment options for 3rd Eyelid Gland Prolapse? what should you NOT do?(1) Manual replacement – usually temporary (2) Surgical options – tacking, Morgan pocket technique, Orbital rim anchoring adenopexy, etc. DO NOT EXCISE THE GLAND YOU WILL CAUSE KCS
3rd Eyelid Gland Prolapse--> when do you use the Morgan Pocket? Where do you place knots? how often does it recurr?Do this on the First offense. Placement of knots on anterior TE (third eyelid) surface. ~20% recurrence rate
3rd Eyelid Gland Prolapse--> when do you use the Orbital rim anchoring adenopexy? What should you know about the pros and cons of this technique?This is a technique you use for RECURRING 3rd eyelid prolapses (ideally you refer this). This is more stable than the morgan pocket technique, but you are PERMANENTLY tacking down the 3rd eyelid so there cant be normal excursions anymore (better to save the tear-producing gland and sacrifice movement tho)
Nictitans Diseases--> Protruding Third Eyelid--> what conformation predisposes animals to this problem?breed related enophthalmos (like great danes, dobermans)
Protruding Third Eyelid--> what can be deceiving that you should keep in mind?Non-pigmented leading edge – can be deceiving (both of these eyes are normal)
Nictitans Diseases--> Protruding Third Eyelid--> what are some pathological causes for this? (4)(1) Decrease in orbital contents (dehydration, emaciation, phthisis bulbi) (2) Increase in orbital contents (neoplasm, abscess, hematoma) (like a tumor pushing the 3rd eyelid up) (3) Sympathetic denervation (Horner’s syndrome) (4) Ocular pain with retractor bulbi contraction (5) Tetanus (Also dysautonomia, a weird dz where autonomic system just goes wonkey, poor prog)
what is horners? main signs of horners?it is sympathetic denervation. elevated 3rd eyelid, ptosis (doopy eyelid), myotic, enopthalmos
what is “Haws” syndrome? (who does this happen in?)happens in CATS, there is BILATERAL PROTRUDING THIRD EYELIDS and concurrent GI signs.
Scrolled Cartilage Malformation of Nictitans--> what is going on? are there breed dispositions for this?this is when the third eyelid cartilage is bent or malformed. LARGE BREED DOGS gets this, Often happens in great danes.
clinical signs of Scrolled Cartilage Malformation of Nictitans?May be none (in which case, ignore it), (chronic) Conjunctivitis, Discharge
how do you tx Scrolled Cartilage Malformation of Nictitans? what should you know about this procedure?Surgical excision of the cartilage-- Should only be performed with appropriate instrumentation. Requires CAREFUL dissection. Avoid sutures on bulbar aspect of 3rd eyelid!! DO NOT excise the gland! (basically approach from palpebral aspect and cut out the kink)
if there is a laceration of the nictitans, what should you make sure to address?Make sure to address exposed sharp cartilage
if there is a FB trapped behind the nictitans, what should you make sure to check?Look for corneal ulcer adjacent
Conjunctivitis of the nictitans might be due to..Follicular hyperplasia
***what is the most common tumor of the TE in domestic animals **?SCC!


Question Answer
what are the 4 major parts of the nasolacrimal system?Puncta (upper & lower), Canaliculi, Lacrimal Sac, Duct
what are the 3 parts (layers kinda but not really) of the tear film?(1) lipid (2) Aqueous (3) mucus
which layer is the lipid portion of the tear film? what is the purpose of it? what makes this portion?Most superficial layer, its job is to Stabilize & prevent evaporation of aqueous layer. It is Produced by the meibomian glands (opening is the grey line!)
which layer is the aqueous portion of the tear film? what is the purpose of it? what makes this portion?Intermediate layer, Provides corneal nutrition; removes waste products. Produced by orbital gland AND gland of the 3rd eyelid
which layer is the mucus portion of the tear film? what is the purpose of it? what makes this portion?deep most layer. Interface of tear film with hydrophobic cornea. Secretory IgA. Produced by conjunctival goblet cells
Aqueous layer “fluid dynamics”--> there is production and there is drainage. which structures are associated with these two important roles?PRODUCTION: Orbital lacrimal gland, 3rd eyelid gland, Accessory glands. DRAINAGE: Puncta, Canaliculi, Nasolacrimal sac, Nasolacrimal duct, Nasal punctum
explain how the tear film moves along and through the eyeTears produced and secreted into “cul-de-sacs”--> Spread by eyelids and 3rd eyelid--> Pool and mix along lower eyelid--> Flow through nasolacrimal duct system
Keratoconjunctivits Sicca (KCS)--> what is happening here (specific part affected)? who does this happen in?Decrease in aqueous component of tear film. Common in dogs and UNcommon in cats
what are different possible etiologies of KCS? (what is the #1 cause??)Immune-mediated - #1 cause, Congenital (Pug, Yorkie), Drug induced (anesthesia, atropine), Drug toxicity (sulfas, Etogesic, Comfortis/others?), Irradiation, Surgical (removal of nictitans gland), Systemic disease (distemper)
which systemic dz can cause KCS?distemper
who is KCS congenital in?pug, yorkie
which drugs INDUCE KCS versus which drugs cause TOXICITY to cause KCS?INDUCE: anesthesia, atropine. (longer under anesthesia, the drier they get) TOX: sulfas, etogesic, comfortis, possibly others (stay away from TMS if at all possible)
how do you dx KSC? (main test? other tests?)SHIRMER TEAR TEST!!!! could also try... Stain (Fluorescein, Rose Bengal), General physical, Culture/Sensitivity, Bloodwork/Thyroid level
WHAT ARE THE NORMALS FOR DOGS FOR KCS? what do the other results mean???>15 mm/60s= Normal, 10-15 mm/60s= Marginal, 5-10 mm/60s= KCS, <5 mm/60s= Severe KCS
what should you know about the schirmer tear test in cats?Low values may be normal! Interpret with clinical signs
what are the clinical signs of KCS? (5)(1) Lackluster cornea (2) Mucopurulent discharge (3) Keratitis (pigment, vessels, ulceration) (4) Discomfort (5) Conjunctivitis (hyperemia, thickening)
if you see mucopurulent dischage, what problem are you thinking of, any why does this happen?think KCS! this is bc there is dec aqueous production, so goblet cells try to compensate by making mucus
how do you tx KCS medically?(1) Tear stimulation and immunomodulation (2) Tear substitutes (3) Tear stimulation (neurogenic KCS) (4) Antimicrobials (5) Mucinolytics (6) antiinflammatories
KCS tx--> Tear stimulation and immunomodulation--> what are the 2 drugs can you give? how long and how much do you have to give for a response?BID x 6 weeks for response. (1) Topical Cyclosporine A (2) Topical Tacrolimus (must be compounded, used when cyclosporin isnt working)
what should you know about tear substitutes as a tx for KCS?Additional lubrication, Frequent application, Lack nutritional aspects of normal tears, Must be given very frequently
when do you use drugs for tear stimulation? what drugs do you give?use for cases of neurogenic KCS (Not recommended for standard cases of KCS- ). Give pilocarpine
before applying medications to tx the KCS, what should you give/do first?Give Mucinolytics to Remove exudates with saline before applying medication--- 5-10% Acetylcysteine
why do you give antiinflammatories with KCS? what must you be careful about?give to Relieve symptoms of conjunctivitis. CAUTION with corticosteroids
Client Education is KEY! KCS IS “Always” FOREVER and you should Teach owners how to properly administer topical medications by telling themRemove mucopurulent debris with sterile saline rinses PRIOR to administering medication(s)! Wait at least 5 mins between drops. Lift up head (dog/cat) or use lavage tube (horses). Warm up tube of ointment to it goes in like a drop
what are the two surgical options for tx of KCS? (1) Parotid duct tranposition (2) Permanent Partial Tarsorrhaphy / Canthoplasty
KCS sx tx--> Parotid duct tranposition--> what should you know about this tx/procedure?Referral surgery, Last ditch effort! must have normal salivation. Also, Medication still typically needed. REMEMBER THAT Saliva ≠ tears. Can lead to some Corneal pigmentation/Mineralization
KCS sx tx: Permanent Partial Tarsorrhaphy / Canthoplasty--> why do we do this?Conservation of existing tears
what is the word for "too much tears"? how much is too much tears?Epiphora- “Overflow of tears onto the face”
what are the two main reasons you'd have epiphora?(1) Excessive lacrimation (irritation) (2) Drainage abnormalities
if there is Excessive lacrimation and you suspect irritation, what are some things you need to R/O?distichia, ectopic cilia, foreign body, tumor, entropion, uveitis, trichiasis, etc.
what are 3 Drainage abnormalities which might lead to epiphora?(1) Obstructions (NL system) (2) Imperforate punctum (3) Dacryocystitis
what is the jones test?does fluorescein stain come out of those nose? confirms intact nasolacrimal duct
how can you dx epiphora?First do a Complete ophthalmic examination, and when you do the Fluorescein stain be sure to look for the Jones test. You can also do a nasolacrimal flush to check patency. Also you can get a C/S, and do radiographs (Skull radiography, CT/MRI, Contrast dacryocystorhinography)
do eval patentcy of the nasolacrimal duct, you can do a Nasolacrimal flush. how do you do this?take a 5 or 10 mL syringe and Fill with eyewash and some fluorescein stain. take a 24 gauge IV catheter with stylette removed and Insert catheter tip in upper lacrimal puncta. Flush around caniliculi, then Occlude lower puncta with finger and flush down nasolacrimal duct
drainage abnormalities--> Potential obstruction locations? (4)Punctum, Canaliculi, Lacrimal sac, Nasolacrimal duct
main etiologies behind obstruction of drainage?(1) Malformation- Imperforate puncta, Displaced puncta (2) Inflammation (3) Infection (Dacryocystitis) (4) Foreign body (5) Skull fractures (6) neoplasia
what is Dacryocystitis? how does it usually present?inflammation of the nasolacrimal system. usually mucopurulent discharge, +/- swelling at medial canthus
Nasolacrimal flush as a tx for obstruction is good to use when? what does it help do?May work for minor obstructions, Removes infectious debris.
obstruction--> sx exploration can be used to do what 2 things?Remove obstruction, Re-establish drainage (she said in class: tube in for at least 6wk)