wk2: AED - Wet Eye Flashcards
What is the role of the Aqueous layer of the tear film? (2)
Provides the tissue with: moisture, oxygen and nutrients
Also: removes waste, flushing mechanism
What is the role of the mucin layer of the tear film? (2)
Allows the aqueous layer to adhere to the epithelial cells of the cornea - by reducing surface tension between these two layers. Therefore acts as a wetting and stabilising agent.
- [increases hydrophilicity of corneal epithelial cells]
Name the tear film layers in order from most to least superficial, and state their thickness (3)
Lipid layer - 0.1um
Aqueous layer - 7um
Mucin layer - 0.05um
How does the lower eyelid relate to lacrimal drainage?
It holds a tear reservoir
How is our tear film replenished?
Replenished with each blink. The meibomian gland produces lipids, then the lids close to meet each other. As the lids open again, the upper lid draws up the lipid into a lipid layer. So a new lipid/oil layer is placed on the tear film with each blink
What is the role of the lipid layer of the tear film?
seals the tear film and reduces evaporation (of tears)
How do the eyelids interact with tears?
Lid action pushes tears to the drainage sites (lacrimal pump)
What is a “lacrimal lake”?
the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system (puncta lacrimalia)
Describe the steps in how tears drain to the nose
- Lid+capillary action - draws tears into lacrimal sac through puncta and canaliculi
- Lacrimal sac - drains via nasolacrimal duct into back of nose
- Valve of Hasner prevents movement the other way
What is the main cause of wet eye?
Reflex tearing (e.g. in response to being poked in the eye, etc. it’s a reflex)
Name 5 causes of Wet Eye (note: there are many others)
Reflex tearing Blocked gland or puncta Epiphora Lacrimal sac obstruction Allergic Rhinitis
(A REBEL is how I’ll remember this)
Define Epiphora
tear overflow from the ocular surface
Name 3 general factors that contribute to wet eye
tear overproduction
poor tear support/movement across surface
impaired tear drainage
List 5 potential symptoms of wet eye that can help us understand its cause
watery eye (uni/bilateral) with fluid leak onto cheek slight discomfort (usually) blurred vision worse in cold/windy conditions worse in hot/dry conditions
Which tears run down your cheek? Basal or Reflex?
Reflex tears. Basal tears stay in your eye
Sometimes when you tell a patient they have dry eyes, the patient will exclaim “No, I have wet eyes!”. What is likely going on to make the patient think this?
The tearing in the eyes in these cases are due to reduction in the normal basal tears and subsequent overcompensation of the lacrimal glands, producing reflex tears
What is the purpose of basal tears?
They coat the surface of your eyes, forming a “tear layer”, which hellps keep your vision clear
Name the 3 types of tears
Basal
Reflex
Emotion (not as much is known about this one. Some studies suggest they contain more toxins then reflex tears so can be good to remove toxins)
What might slight discomfort in a patient with wet eye indicate about aetiology?
Could be overproduction/dry eye related
What might tears running down the face of a wet eye patient indicate about aetiology?
Could be dry eye related
What might wet eye symptoms being worse in cold/windy conditions indicate about aetiology of the wet eye?
Usually means the problem is anatomical or obstructional
What might wet eye symptoms being worse in hot/dry conditions indicate about aetiology of the wet eye?
Usually overproduction/dry eye related
Name 5 signs of wet eye
Increased marginal tear prism Lid anomalies Drainage blockage Dry eye Stenosed (narrowed) puncta
Why do we have 2 puncta?
Our drainage system relies on both gravity and the movement of eye muscle, which causes a wave of contraction and causes the punctum hole to open and draw in debris
What questions should you ask/things to consider in history when dealing with a wet eye patient? (11. Try and remember 5)
Age (e.g. infants)?
True tear spillage or just poor vision?
When are symptoms worst; are they acute or chronic?
Associated Discomfort?
Previous therapy for these symptoms?
Previous CNVII related events, tearing while eating?
Medication?
Red eye, discharge, lid crusting, allergies?
Pain or swelling near lacrimal sac (or gland)?
Surface trauma?
Lid or conjunctiva trauma/surgery/scarring?
