AED - Dry Eye Assessment - Week 4

Question 1

Describe the thickness and origin of each of the three layers of the tear flim.

Answer 1

Lipid phase - meibomian gland - 0.1μm
Aqueous phase - lacrimal gland and conjunctiva - 7μm
Mucoid phase - goblet cells - 0.05μm

Question 2

Describe the two kinds of dry eye disease and list the subclassifications for each (7).

Answer 2

Tear-deficient

• sjogren’s syndrome
• non-sjogren tear deficient

Evaporative

• oil deficient
• aqueous deficient
• lid related
• contact lens
• surface change

Question 3

List three possible causes of aqueous deficient dry eye.

Answer 3

Tear hyperosmolarity
Tear film instability
Reflex block

Question 4

List three possible causes of reflex block.

Answer 4

Refractive surgery
CL wear
Topical anaesthesia

Question 5

List four possible causes of tear film instability.

Answer 5

Xerophthalmia
Ocular allergy
Preservatives
CL wear

Question 6

List four possible causes of evaporative dry eye.

Answer 6

Environment
Deficient or unstable tear flim lipid layer
Blepharitis
Lid flora

Question 7

List the two broad classifications for evaporative dry eye. For each, list four subclassifications and an example if applicable.

Answer 7

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)

Question 8

Can dry eye be asymptomatic? Explain.

Answer 8

Yes, it can be due to neurotrophic conditions or a predisposition to dry eye
Preventative management is needed

Question 9

What if a patient presents complaining of dry eye, but there are no signs of dry eye upon assessment (2)?

Answer 9

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

Question 10

What are the four main causes of dry eye? What may occur secondary to these causes and what is a consequence of this?

Answer 10

Reduced aqueous production
Mucin deficiency
Lipid deficiency
Lid/ocular surface abnormality
Inflammation can occur secondary to these, and perpetuate the disease

Question 11

What can cause mucin deficiency?

Answer 11

Goblet cell destruction

Question 12

List a primary and secondary cause of reduced aqueous production.

Answer 12

Primary - gland dysfunction/blockage

Secondary - abnormal neural reflex/control

Question 13

Is primary inflammation a possible cause of dry eye disease or only secondary?

Answer 13

Primary can also be a precipitating factor

Question 14

Can reduced aqueous production occur in sjogren’s syndrome?

Answer 14

Yes

Question 15

Can systemic or topical drugs cause reduced aqueous production?

Answer 15

Yes

Question 16

Aside from goblet cell dysfunction, list three possible causes of mucin deficiency.

Answer 16

Vitamin A deficiency
Systemic or topical drugs
Severe ocular surface inflammation/trauma

Question 17

List four possible causes of lipid deficiency.

Answer 17

Lid disease
Meibomian gland dysfunction
Systemic/topical drugs
Lid inflammation/trauma

Question 18

List 6 conditions that can result in blink abnormalities.

Answer 18

Desensitised cornea
Bell's palsy
Concentrated use of eyes (TV/PC etc)
Coma
Parkinsons disease
Systemic/topical drugs

Question 19

List 5 conditions that can result in eyelid malposition.

Answer 19

Exophthalmos
Ectropion
Entropion
Lagophthalmos
Bell's palsy

Question 20

List 6 conditions that can cause surface disruption leading to dry eye.

Answer 20

Contact lenses
Flitering bleb
Pterygia/pingueculae
Tumours
Trachoma/scarring
Inflammation

Question 21

Is smoking a risk factor for, or protective against dry eye?

Answer 21

Risk factor

Question 22

Is ocular surface staining sensitive to severity?

Answer 22

No

Question 23

hat is the osmolarity cutoff for dry eye?

Answer 23

> 308mOsm/L

Question 24

What is the cutoff for Shirmer’s test?

Answer 24

<5mm

Question 25

List four symptoms of dry eye.

Answer 25

Scratchy eyes
Burning
Gritty feeling
Foreign body sensation

Question 26

What 7 factors can worsen dry eye?

Answer 26

Worse on waking
Hot dry locations
Air conditioning
Smoky areas
Wind
Low humidity
Computer use

Question 27

Can excessive tearing occur with dry eye?

Answer 27

Yesd

Question 28

Can vision loss occur with dry eye?

Answer 28

Yes, mild to moderate

Question 29

List 7 signs of dry eye.

Answer 29

Excess mucus/debris/foam/oil in tear film
Reduced or absent tear prism/meniscus (1mm)
Conjunctival hyperaemia
Wrinkles/scarring
Corneal erosion/ulceration/vascularisation/scarring
Blurred/fluctuating vision
Lid disease

Question 30

What is the response of dry eye to phenol red thread?

Answer 30

Reduced

Question 31

What kind of appearance do dry eyes have under staining (2)?

Answer 31

SPK and conjunctival staining

Question 32

Explain the workup for a patient with dry eye (8).

Answer 32

History
Symptomatology
Vision
Slit lamp (lid health, tear prism, breakup time etc)
Fluorescein staining
Cotton/Schirmer's test
Rose bengal/lissamine green or equivalent
Tear osmolarity