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