AED - Dry Eye Assessment - Week 4 Flashcards
Describe the thickness and origin of each of the three layers of the tear flim.
Lipid phase - meibomian gland - 0.1μm
Aqueous phase - lacrimal gland and conjunctiva - 7μm
Mucoid phase - goblet cells - 0.05μm
Describe the two kinds of dry eye disease and list the subclassifications for each (7).
Tear-deficient
- sjogren’s syndrome
- non-sjogren tear deficient
Evaporative
- oil deficient
- aqueous deficient
- lid related
- contact lens
- surface change
List three possible causes of aqueous deficient dry eye.
Tear hyperosmolarity
Tear film instability
Reflex block
List three possible causes of reflex block.
Refractive surgery
CL wear
Topical anaesthesia
List four possible causes of tear film instability.
Xerophthalmia
Ocular allergy
Preservatives
CL wear
List four possible causes of evaporative dry eye.
Environment
Deficient or unstable tear flim lipid layer
Blepharitis
Lid flora
List the two broad classifications for evaporative dry eye. For each, list four subclassifications and an example if applicable.
Intrinsic
- meibomian oil deficiency
- lid aperture disorder
- low blink rate
- drug action (accutane)
Extrinsic
- vitamin A deficiency
- topical drugs (preservatives)
- contact lens wear
- ocular surface disease (allergy)
Can dry eye be asymptomatic? Explain.
Yes, it can be due to neurotrophic conditions or a predisposition to dry eye
Preventative management is needed
What if a patient presents complaining of dry eye, but there are no signs of dry eye upon assessment (2)?
It could be a preclinical state, in which case you offer preventative therapy
It could be neuropathic pain, in which case you would refer for pain management
What are the four main causes of dry eye? What may occur secondary to these causes and what is a consequence of this?
Reduced aqueous production Mucin deficiency Lipid deficiency Lid/ocular surface abnormality Inflammation can occur secondary to these, and perpetuate the disease
What can cause mucin deficiency?
Goblet cell destruction
List a primary and secondary cause of reduced aqueous production.
Primary - gland dysfunction/blockage
Secondary - abnormal neural reflex/control
Is primary inflammation a possible cause of dry eye disease or only secondary?
Primary can also be a precipitating factor
Can reduced aqueous production occur in sjogren’s syndrome?
Yes
Can systemic or topical drugs cause reduced aqueous production?
Yes
Aside from goblet cell dysfunction, list three possible causes of mucin deficiency.
Vitamin A deficiency
Systemic or topical drugs
Severe ocular surface inflammation/trauma
List four possible causes of lipid deficiency.
Lid disease
Meibomian gland dysfunction
Systemic/topical drugs
Lid inflammation/trauma
List 6 conditions that can result in blink abnormalities.
Desensitised cornea Bell's palsy Concentrated use of eyes (TV/PC etc) Coma Parkinsons disease Systemic/topical drugs
List 5 conditions that can result in eyelid malposition.
Exophthalmos Ectropion Entropion Lagophthalmos Bell's palsy
List 6 conditions that can cause surface disruption leading to dry eye.
Contact lenses Flitering bleb Pterygia/pingueculae Tumours Trachoma/scarring Inflammation
Is smoking a risk factor for, or protective against dry eye?
Risk factor
Is ocular surface staining sensitive to severity?
No
hat is the osmolarity cutoff for dry eye?
> 308mOsm/L
What is the cutoff for Shirmer’s test?
<5mm
