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IP 11 Ophthalmology > 3: Nictitans / Nasolacrimal - giuliano > Flashcards

3: Nictitans / Nasolacrimal - giuliano Flashcards

1
Q

what is epiphora?

A

tear production - serous exudate

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2
Q

what is physis bulbi?

A

end stage, shrunken eye

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3
Q

what is the Nictitias?

A

3rd eyelid

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4
Q

what is the topographical distribution of the Nictitans?

origin, shape, important features of it

A

origin: anterior ventro medial orbit
shape: triangular, covered w conjunctiva
contains “T-shaped” hyaline cartilage runs through the center
at the base, has bland of the 3rd eyelid

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5
Q

what is the function of the Nictitians?

A
  • to protect the globe
  • sec and distribution of tears
  • aid in removal of particulate matter from the eye
  • “windshield wiper”
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6
Q

t/f

the movement of the 3rd eyelid is an active process

A

false

passive

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7
Q

what does the movement of the 3rd eyelid depend on?

A
  • orbital tone
  • orbital fat
  • hydration status
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8
Q

t/f

an animal with little fat or who is dehydrated will become enopthalmic and will display an elevated 3rd eyelid as a result

A

true

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9
Q

where is the gland of the 3rd eyelid loc?

A

encompasses the base of the cartilage

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10
Q

what type of secretion is produced by the gland of the 3rd eyelid?

from what aspect and structures is the material secreted?

A
  • seromucous secretions
  • exit thru ducts that open into the posterior aspect of the 3rd eyelid btwn lymphoid
  • on bulbar aspect of 3rd eyelid, it is normal to have a complement of lymphoid follicles, that look like cobble stones
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11
Q

how much basal tear production can be attributed to the gland of the 3rd eyelid?

A

30% - 70%

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12
Q

t/f

a common and appropriate treatment to a consistently prolapsing 3rd eyelid gland is removal

why or why not?

A

FALSE - THE 3RD EYELID SHOULD BE REMOVED ONLY IF IT IS CANCEROUS

risk: predisposes animal to dry eye - keratoconjunctivitis secca => BAD

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13
Q

2 classifications of 3rd eyelid dz?

A
  • dz of the conjunctiva that affects the 3rd eyelid

- 1* dz of the 3rd eyelid

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14
Q

what are 1* dzz of the 3rd eyelid?

A
  • gland prolapse
  • elevated 3rd eyelids
  • malformed or scrolled cartilage
  • neoplasia
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15
Q

when does 3rd eyelid gland typically prolapse? and in what species?

A

dogs

less than 1 yo

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16
Q

what is the common term for 3rd eyelid gland prolapse?

A

cherry eye

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17
Q

what are proposed causes of 3rd eyelid gland prolapse?

A
  • weak fascial attachments to the ventromedial orbit

- immune stimulation [often dogs have been vaccinated a few weeks before this occurs]

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18
Q

what are the clinical implications of a prolapsed 3rd eyelid gland?

A
  • conjunctivitis / chronic irritation
  • KCS
  • cosmetic concerns
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19
Q

tx of prolapsed 3rd eyelid gland?

A
  • manual replacement [usually temporary]

- surgical - complicated!

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20
Q

post op care for prolapsed gland of the 3rd eyelid?

A

topical abx [broad spectrum]
systemic anti inflammatory
cone of shame

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21
Q

common causes of prolapsing 3rd gland of the eyelid:

A
  • conformation [breed enophthalmos]
  • non pigmented leading edge [can be deceiving and look uneven; common in merle often]
  • dec in orbital contents [deh, emaciation, phthisis bulbi, microphthalmos]
  • inc in orbital contents [neoplasia, abscess, hematoma]
  • sympathetic denervation [horner’s syndrome]
  • ocular pain w retractor bulbi contraction
  • rare: tetanus, dysautonomia
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22
Q

t/f

the signs of Horner’s syndrome, due to loss of sympathetic tone, occur b/c the 3rd eyelid has lost its sympathetic innervataion

A

false

there is not sympathetic tone in extra orbital Mm

the sympathetic tone is in the peri orbita [orbital cone] so this loses its tone, causing the globe to sink back and the eyelid comes up

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23
Q

what signs are seen in Horner’s syndrome?

A

ptosis
elevated 3rd eyelid
enophthalmos
myosis

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24
Q

what is “haws” syndrome?

what species?

A

cats

bilateral involvement
concurrent GI signs

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25
Q

what is cause of scrolled cartilage malformation of nictitans?

A
  • 3rd eyelid cartilage is bend or malformed
    the tail of the “T” bends backwards
  • breed predispositions [large breed dogs]
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26
Q

c/s of scrolled cart of 3rd eyelid?

A

none
conjunctivitis
discharge

27
Q

tx for scrolled cartilage?

A

surgical excision of the cartilage

28
Q

t/f

an alternative tx for scrolled cartilage is excision of the gland of the 3rd eyelid

A

false

do NOT remove gland of the 3rd eyelid

29
Q

tx for laceration of nictitans?

A

address exposed sharp cartilage

30
Q

common cause of corneal ulcer, related to the 3rd eyelid?

A

foreign body behind the 3rd eyelid - anesthetize animal and look behind the eyelid

31
Q

t/f

lymphoid tissue on the palpabral surface of the 3rd eyelid is normal

what is the significance of this?

A

false

abnormal
lymphoid tissue is normally on the bulbar aspect of the eyelid

lymphoid tissue on the palpebral surface indicated lymphoid conjunctivitis and follicular hyperplasia

32
Q

what is the MC neoplasia found on 3rd eyelid?

Tx?

A

SCC

remove the 3rd eyelid

33
Q

what is the significance of SCC of the 3rd eyelid in cattle?

A

it is the MC reason for condemnation of carcass at slaughter

34
Q

what is the anatomy of the nasolacrimal system?

A

superior and inferior puncta lead to canaliculi -> leads to lacrimal sac -> leads to naso lacrimal duct -> leads to nares and out the nasal punctum

35
Q

what are the 3 components to the tear film? list them from superficial to deep

A

lipid
aqueous
mucus

36
Q

what is the function of the lipid component of the tear film?

where is it produced?

A
  • stabilize and prevent evaporation of aqueous layer

- produced by the Meibomian glands in the eyelid

37
Q

what is the function of the aqueous component of the tear film?

where is it produced?

A
  • provides corneal nutrition and removes waste products

- produced by the orbital gland and the gland of the 3rd eyelid

38
Q

what is the function of the mucus component of the tear film?

where is it produced?

A
  • interface of tear film with hydrophobic cornea
  • secretory IgA
  • prod by conjunctival goblet cells
39
Q

if comparing the aqueous layer fluid dynamics within the nasolacrimal [NL] anatomy to a sink, which parts are the faucet and drain?

A

faucet = orbital lacrimal gland, gland of the 3rd eyelid, accessory gland

drain = naso lacrimal outflow tract [puncta, canaliculi, NL sac, NL duct, nasal punctum]

40
Q

how does fluid flow across the eye?

A
  • tears produced and secreted into “cul-de-sacs”
  • spread by eyelids and 3rd eyelid
  • pool and mix along lower eyelid
  • flow thru NL duct sys
41
Q

what 2 basic categories do dzz of tear film dynamics fit into?

A

too much production

too little production

42
Q

what dz is too little tear film production called?

common name?

A

KCS

dry eye

43
Q

KCS is the dec in prod of which component of the tear film?

common and uncommon in what species?

A
  • dec in aqueous component

common: dogs
uncommon: cats

44
Q

what is the etiology of KCS?

A 
#1: immune mediated
congenital [breed - pug, yorkie]
drug induced [anesthesia, atropine]
drug toxicity [sulfas, Etogesic, comfortis]
irradiation
sx - removal of 3rd eyelid gland
systemic dz - distemper
45
Q

how to dx KCS?

A

Schirmer Tear Test (STT)

46
Q

what are normal values for dogs and cats for STT?
marginal?
KCS?
severe KCS?

A

normal dogs: over 15mm/60s
10-15 mm/60s = marginal
5-10 mm/60s = KCS
less than 5mm/60s = severe KCS

cats: tend to be lightly lower values; interpret test in context of c/s

47
Q

c/s KCS?

A
  • lackluster cornea
  • mucopurlent discharge
  • keratitis: pigment, vessles, ulceration
  • discomfort
  • conjunctivitis: hyperemia, thickening
48
Q

why does mucopurulent discharge occur during KCS?

A

not enough aqueous component to tear film
often 2* bacT infection
goblet cells in over drive to prod more mucus b/c innervation detects dry eye

49
Q

KCS tx?

A
  • tear stimulation and immunomodulation, BID for 6 weeks
  • topical cyclosporine A [ointment]
  • topical tacrolimus [compounded for cyclosporine non responders]
  • tear substitutes: additional lubrication, frequent application, lack nutritional aspects of normal tears, give frequently
50
Q

t/f

a more simplified and effective treatment for KCS is tear substitutes alone

A

false

tear substitutes need to be used as an adjunctive therapy

51
Q

what function is topical cyclosporine or tacroliums in the Tx of KCS?

A

potent T cells suppressors

to target the immune mediated aspect of KCS, which is the MC cause in dogs

52
Q

how is the Tx of neurogenic KCS different than typical KCS treatment?

A
  • stimulate tear production with Tx: pilocarpine = parasympathomimetic
    usually used for glaucoma - put in food and titrate dose until animal gets SLUDD or vomits then bring dose down
    **note: not for standard KCS cases

abx - for 2* bacT infections; short term

mucinolytics - remove exudates w saline before applying medication: 5-10% acetylcysteine

53
Q

if using corticosteroids to Tx KCS, what is the best way?

why?

A
  • give orally

caution: can suppress immune system too much and essentially “melt” the cornea

54
Q

what aspects of client education are KEY?

A
  • remove mucopurulent debris w sterile saline rinses prior to administering medications
  • wait at least 5 mins btwn drops
  • lift up head and bring bottle around back of eye or use lavage tube
  • warm up tube of ointment
55
Q

pilocarpine and other drugs used to Tx KCS may be irritating long term and cause uveitis. what surgical options are there to help the condition?

A
  • parotid duct transposition: after Sx, salivation will help lubricate eyes BUT may lead to corneal pigmentation and mineralization b/c saliva is not equivalent to tears
  • permanent partial tarsorrhaphy / canthoplasty: narrow eyes to conserve existing tears
56
Q

if patient has epiphora, or is producing too much tear film, what are differentials?

A
  • excessive lacrimation due to irritation: distichia, ectopic cilia, foreign body, tumor, entropion, uveitis, trichiasis
  • drainage abnormality: obstruction of NL sys, importorante punctum, dacryocystitis
57
Q

what test is used to determine patency of NL duct system?

A

Jones test - fluorescent stain in eye and 5 mins later, it should be coming out the nose

58
Q

how to Dx epiphora?

A
  • complete ophthalmic exam
  • Jones test
  • NL flush
  • culture and sensitivity
  • x ray, CT/MRI, contrast dacryocystorhinography
59
Q

how to evaluate patency of NL duct system using a NL flush?

A

5-10 mL syringe
fill w eyewash and fluorescent stain
24 gauge IV catheter w stylette removed
insert catheter tip in upper lacrimal puncta
flush around caniliculi
occlude lower puncta w finger and flush down NL duct

60
Q

epiphora Tx?

A
  • Tx 1* cause - often refer for more invasive examination
  • Tx 2* infection - common w obstruction of NL sys
  • anti inflammatories maybe
61
Q

what are common locations for obstruction of NL system?

A

punctum
canaliculi
lacrimal sac
NL duct

62
Q

etiologies of NL drainage abnormalities?

A

malformation [imperforante puncta, displaced puncta]

inflammation

infection [dacryocystitis]

foreign body

skull fractures

neoplasia

63
Q

what is dacryocystitis?

c/s?

A

inflammation of NL duct sytsem

mucopurulent discharge, possible swelling at the medial canthus

64
Q

NL obstruction therapy?

A
  • NL flush [minor obstruction, infectious debris out]
  • Abx [2* infections]
  • Sx exploration [ID and remove foreign bodies, re-route NL drainage]

IP 11 Ophthalmology (13 decks)

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