Lacrimal System Flashcards
abnormal overproduction of tears
common response to ocular irritation
epiphora
epiphora is a common response to
ocular irritation
present in the conjunctival epithelium and produce the innermost mucous layer of the 3-layer tear film. Patients with conjunctivitis will often overproduce mucus, conventionally referred as mucoid discharge
goblet cells
a very common clinical sign with conjunctivitis
mucoid discharge
what is most commonly found is cases of KCS due to loss of aqueous portion of the tear film
mucopurulent discharge
-mucous overproduction, bacterial overgrowth and subsequent white blood cell recruitment
classic feature on KCS
why is there mucopurulent discharge in KCS cases
mucous overproduction, bacterial overgrowth and subsequent white blood cell recruitment
classic feature on KCS
infection or inflammation of any portion of the lacrimal system
Dacryocystitis
what is the path of drainage of the nasolacrimal system
1) Lacrimal puncta
2) Canaliculi
3) Lacrimal sac
4) Nasolacrimal duct
5) Nasal puncta
what makes the aqueous layer of the tear film *
orbital lacrimal gland
gland of the third eye lid
what makes the mucin layer of the tear film *
conjunctival goblet cells
what makes the lipid layer of the tear film
meibomian glands
from innermost outermost, what are the layers of the tear film *
Mucin: binds serous layer to cornea (innermost)
Aqeuous: majority of tear function (middle)
Lipid(outer layer)
increases surface tension
slwos tear evaporation
What are the 7 functions of the tear film?
1) smooth ocular surface for refraction of light
2) Lubrication of ocular surface and eyelids
3) Remove metabolic by-products from corneal surface
4) Provide oxygen and nutrients to the corneal surface
5) Give white blood cells access to the conjunctiva
6) Remove debris and foreign material from the ocular surface
7) Defend ocular surface from pathogens
What is the afferent nerve of the lacrimal system
Trigeminal V- ophthalmic branch
corneal and conjunctival afferents
What is the efferent nerve of the lactrimal system
parasympathetics (from VII)
Nasolacrimal flush
used to assess the nasolacrimal system
-use 23-27g metal cannula, tom cat catheter or IV catheter and saline
-Can canulate uppoer or lower puncta
-Obserbe flow out opposite puncta and nares or swallowing
-Topical anesthesia is necessary may need general anesthesia
How long does it take for the fluorescein dye to travel from the eye to the nares
30seconds to 5 minutes in dogs and cats
How do you perform a Jones test
1) instill fluorescein into the eye
2) Lower head/nose
3) Observe fluorescein in the nares or oral cavity
4) 30 seconds to 5 min in dogs and cats
High unreliable in horses
What can you use to test the quantity of the tear film *
STT I measures lacrimal quantity
-basal and reflex tearing
STT II measures _________ *
only the basal tear production (after 1 drop of anesthetic)
Schirmir tear test interpretation
15-25mm = Normmal range
10-14mm = suspect low tears
<10mm = inadequate tears
What does STT I measure
basal + reflex tearing
why should you not touch the tip of the strip
lipids on fingers may prevent tear absorption
how hsould you keep the schirmer tear test in
keep in middle of lower eyelid +/- close lids for 1 minute
What is normal Schirmer tear test I production in dogs
15mm wetting / 60 seconds
What is normal Schirmer tear test I production in horses
> 10mm/60 sec
What is normal Schirmer tear test I production in cats
> 5mm/60 seconds
How do you assess the quality of the tear film
Tear Film Break Up Time
-Apply fluorescein stain to cornea
-hold lids open and prevent blinking
-should take at least 20 seconds for tear film to break up and dark regions to form in normal eye
abnormal tear film breaks up too quickly or too slowly
Indication of mucin quality in the tears
Tear Film Break Up Time is an indication of
mucin quality in the tears
In Tear Film Break Up Time, how long should it take for the tear film to break up and drak regions to form in normal eye
at least 20 seconds
abnormal tear film breaks up too quickly or too slowly
-indication of mucin quality in the tears
What does the Rose Bengal stain do
Stains devitalized or degenerated epithelial cells as well as mucous filaments
What is the phenol red thread test
75mm long thread that is a pH indicator
15 second test
alkaline tears turn the thread red
Dogs: 34mm +/- 4.5
Cats: 24mm +/- 2.23
measureas tears in inferior cul de sac
__________ tears turns the phenol red thread test red
alkaline
tear overflow can result from
1) overproduction - irritation
2) decreased drainage - obstruction
must evaluate which part of system is dysfunctional in order to devise most effective treatment (lacrimal glands or 3rd eyelid, canaliculi and sac, nasolacrimal duct)
flow of tears onto the face as a result of decreased drainage or increased production of tears
epiphora
why do tears turn brown on the face
porphyrins
do dogs have more meibomian glands on upper or lower lid
upper > lower
what portion of the tear film does the schirmir tear test test?
aqueous portion
What causes increased tear production
very non-specific sign of ocular pain
may result from intraocular disease or ocular surface disease
rule out nasolacrimal drainage problem, then look for reasons of excessive tearing
-foreign body? abnormal cilia?
What might cause decreased outflow?
1) Punctal atresia- congenital abnormality
need to surgically break down the membrane over the puncta
2) Dacryocystitis- obstruction of nasolacrimal system by foreign object or inflammation
may require aggressive lavage, advanced imaging
is acute epiphora tend to be from increased tear production or reduced outflow
increased production - some sort of irritation to the eye
punctal atresia
congenital abnormality
need to surgically break down the membrane over the puncta
obstruction of nasolacrimal system by foreign object or inflammation
dacryocystitis
What are the clinical signs of dacryocystitis
epiphora or mucoid discharge
negative Jones Test
How do you treat dacryocystitis
-topical antibiotic/anti-inflammatories
-Placement of a nasolacrimal stent while duct is healing (prevent structure/stenosis)
-May require aggressive lavage/ irrigation while lifting the puncta (beware might cause fibrosis if done a lot over time)
How can tear film abnormalities lead to cornea cell damage and inflammation
decreased oxygen and other nutrients to cornea and conjunctiva (increased waste)
What is the most common form of Keratoconjunctivitis sicca (KCS) **
quantitative
-deficiency of aqueous layer
-dogs most frequently affected
qualitative Keratoconjunctivitis sicca (KCS)
deficency of mucus or lipid layers
harder to diagnose- USe TFBUT test
treat with hyaluronic acid based drop or gel to stabilize tear film
How do you treat qualitative Keratoconjunctivitis sicca (KCS) *
hyaluronic acid based drop or gel to stabilize tear film
What causes Keratoconjunctivitis sicca (KCS)*
1) T cell mediated destructionof lacrimal tissue *
2) Metabolic disease: Diabetes mellitus, Cushigns
3) Drug induced: Sulfa antibiotics, Etodolac (NSAID), atropine (temporary)
4) Infectious: Canine distemper, FHV-1
5) Congenital hypoplasia/aplasia of lacrimal gland
6) Cherry eye
7) Iatrogenic - removal of 3rd eyelid
8) Anesthesia
9) Neurogenic (CN VII- parasympathetic deficit, ear infection)
10) Radiation
11) Trauma
What are the clinical signs of Keratoconjunctivitis sicca (KCS)*
Decreased lubrication
Decreased corneal clarity
Increased corneal and conjuncntival irritation
Decreased antimicrobial activity
Increased corneal and conj. infection
What metabolic diseases cause Keratoconjunctivitis sicca (KCS) *
Diabetes mellitus
Cushings
What drugs induce Keratoconjunctivitis sicca (KCS) *
Sulfa antibiotics
Etodolac (NSAID)
Atropine (temporary)
infectious causes of Keratoconjunctivitis sicca (KCS)
canine distemper virus
FHV-1
What are the clinical signs of KCS **
Mucoid, ropy tenacious discharge
Conjunctival hyperemia/ conjunctivitis
Corneal vascularization
Corneal pigmentation
Corneal fibrosis
Corneal ulceration
Lacluster corneal surface
Blepharitis
Loss of vision
How do you diagnose Keratoconjunctivitis sicca (KCS) **
-Decrease in STT values
-Clinical signs:
Mucoid, ropy tenacious discharge
Conjunctival hyperemia/ conjunctivitis
Corneal vascularization
Corneal pigmentation
Corneal fibrosis
Corneal ulceration
Lacluster corneal surface
Blepharitis
Loss of vision
How do you medically treat Keratoconjunctivitis sicca (KCS) *
LAAT
Lacrimostimulants
Antibiotics
Anti-inflammatories (if not ulcers)
Tear Replacement
What are lacrimostimulants used to treat Keratoconjunctivitis sicca (KCS) *
Topical Cyclosproin A 0.2% or Tacrolimus 0.01-0.02% (more potent)
function to inhibit T cells from infiltration and destroying lacrimal gland
Tacrolimus»_space;» Cyclosporine
generally TID
6-8 weeks to reach efficacy *
Add on Pilocarpine for neurogenic KCS
For treatment of Keratoconjunctivitis sicca (KCS), how long does it take Cyclosproin A 0.2% or Tacrolimus 0.01-0.02% to reach effiacacy *
6-8 weeks to reach effiacacy
What do you use to treat neurogenic KCS
Pilocarpine additionally to Cyclosporine A or Tacrolimus - helps stimulates parasympathetic system (CN VII) innervation to lacrimal gland
helps stimulates parasympathetic system (CN VII) innervation to lacrimal gland
Pilocarpine
For Keratoconjunctivitis sicca (KCS), what should you do if the dog presents with conjunctivitis or corneal ulcer is present *
Topical antibiotic
-Tobramycin
-Terramycin
-Neomycin and Polymyxin B Sulfates and Bactricin (Tripe Antibiotic)
How should you treat Keratoconjunctivitis sicca (KCS) inflammation if the cornea doesnt have an ulcer *
Anti-inflammatories - if keteraitis is present but no corneal ulcers
-Topical NSAID: Diclofenac
-Topical Steroid: NeoPolyDex > Prednisone Acetate
For Keratoconjunctivitis sicca (KCS), why is topical Neopolydex better than prednisolone acetate when there is no ulcer present but keratitis?
Prednisolone has good chamber and enters the anterior chamber
Dexamethasone only works surfacely at the cornea
What should you use as tear replacement in Keratoconjunctivitis sicca (KCS) cases *
gel or ointment preferable (longer lasting)
more frequent administration until tear stimulant has reached efficacy (every 2-3 hours in severe cases)
Surgical treatment options for Keratoconjunctivitis sicca (KCS) *
1) Parotid duct transposition- duct from parotid is rerouted up to eye (palpebral conjunctiva)
creates spit eyes- ends with lots of calcium deposits
2) Subconjunctival silicone cyclosporine implant - well tolerated in dogs, for dogs not responsive to topic CsA
ESMC iplant controlled signs of KCS in horse
Eliminates the need for topical medication
Need to be changed every year
also used for some pannus
What is a side effect of parotid duct transposition
calcium deposits in the eye
