Nasolacrimal System

Question 1

Where are tears secreted from?

Answer 1

Lacrimal gland, TEL gland, eyelid glands (meibomian glands & goblet cells)

Question 2

What makes up the pre-corneal tear film?

Answer 2

mucin: golbet cells secrete which keeps cornea smooth and allows tears to adhere to cornea lipid: meibomian glands secrete- it helps to decrease evaporation aqueous: made from 3 areas-keeps cornea moist

Question 3

Answer 3

Epiphora: spilling of tears

occurs when tear outflow is obstructed

1. wicking- aberrant cilia, strange eyelids
2. lipid defect-tears don’t stay against cornea
3. pain- excessive production of tears

Question 4

Answer 4

Imperforate puncta: non painful congential defect that leads to chronic epiphora

lacks opening at puncta

sx to open

Question 5

Dog with 4 month history of chronic conjunctivitis that has been non-responsive to ABx. Presents with epiphora and purulent discharge, when you use fluorescein stain it doesn’t exit the nares

Answer 5

Nasolacrimal obstruction

common in hunting/outdoor dogs

cheatgrass, etc gets stuck inside

gently flush to try to remove

Question 6

Dog presents with epiphora- when you place stain it gets onto the hairs around the eye

Answer 6

Epiphora caused by wicking aberrent cilia touching cornea

Question 7

stain shows tear spilling onto eyelids

Answer 7

Excessive tearing most likely due to poor tear quality (no source of pain)

doesn’t hold tear onto cornea so it spills over

common in brachycephalic breeds because their puncta doesn’t function normal

Question 8

what is the normal tear flow rate for a STT? What nerve is sensing the irritation in the test?

Answer 8

15-25mm/min

CN 5 (Sensory) Trigeminal

Question 9

This dog has 5 mm/min on the STT- what condition is this?

Answer 9

KCS: KeratoConjunctivitis Sicca “Dry Eye”

Lack epiphora despite painful eyes (squinting)

See corneal pigment and vasculature along with decreased tears