AED - Wet Eye - Week 2 Flashcards
How thick is the tear flim? Describe each layer, where it comes from, and how thick they are.
Total thickness is ~7.15μm
Lipid phase - meibomian glands - ~0.1μm
Aqueous phase - lacrimal glands and conjunctiva - ~7μm
Mucoid phase - goblet cells - ~0.05μm
What does lid action do to the tear flim?
Pushes it to the drainage sites
What do meibomian secretions aid in, and what may it limit?
Aids in spreading and may limit overflow
What forms in the eye concerning the tear film?
A lacrimal lake at the margin of the bottom eyelid
Describe all the structures of the lacrimal drainage system (5).
At the nasal margin of the eyelids is found two puncta (one for each eyelid) which drains into a canaliculus. These two canaliculi merge nasally to form the common canaliculus.
This drains into the naso-lacrimal sac.
This drains into the naso-lacrimal duct.
At the bottom of this duct is the valve of hasner.
What two forces draw tears into the naso-lacrimal sac?
Lid and capillary action
Where does the nasolacrimal duct drain to?
The back of the nose
What does the valve of hasner prevent?
Backflow
Define epiphora.
Tear overflow from the ocular surface
List three possible mechanisms of epiphora.
Tear overproduction
Poor tear support / movement
Impaired tear drainage
List 3 symptoms of epiphora.
Watery eye
Slight discomfort
Blurred vision
What can be said of epiphora if it is worse in cold/windy conditions (2)?
Usually anatomical / obstructive
What can be said of epiphora if it is worse in hot/dry conditions (2)?
Usually overproduction / dry eye related
List 5 signs of epiphora.
Increased marginal tear prism Lid anomalies Drainage blockage Dry eye Stenosed (narrowed) puncta
List 11 history questions you would ask for epiphora.
Age? True tear spillage or just poor vision? When are symptoms worse? Associated discomfort? Previous therapy? Previous CNVII related events, tearing while eating? Medication? Red eye/discharge/crusting/allergies? Pain/swelling? Surface trauma? Lid or conj. trauma/surgery/scarring?
When doing a slit lamp examination for epiphora, list 5 things to look out for.
Facial characteristics - entropion/ectropion Normal lid movement Lacrimal gland swelling Punctal conformation/patency Ocular surface condition
List 4 techniques (aside from slit lamp) that can be used to assess epiphora.
Lacrimal sac expression (pressure)
Lacrimal lavage (irrigation)
Fluorescein tests
Cotton thread/schirmers test