DIS - Dry Eye Tutorial - Week 1

Question 1

Give the TFOS DEWS II definition of dry eye disease (8).

Answer 1

Dry eye is a MULTIFACTORIAL DISEASE of the ocular surface characterised by a LOSS OF HOMEOSTASIS of the tear film, and accompanied by OCULAR SYMPTOMS, in which TEAR FILM INSTABILITY and HYPEROSMOLARITY, ocular surface INFLAMMATION and DAMAGE, and NEUROSENSORY abnormalities play aetiological roles

Question 2

List the 4 components of the lacrimal functional unit, including associated innervation (2). What does disruption to one or more of these components promote?

Answer 2

Lacrimal gland
Ocular surface components
Meibomian glands
Eyelids
Sensory innervation CNV
Autonomic innervation CNVII
Disruption to one or more of these promotes loss of tear homeostasis

Question 3

Describe the nerve layout at the corneal epithelium (2).

Answer 3

Subbasal nerves run along the basal cell layer, and intraepithelial terminals run up through the wing cell layer to the epithelial surface cells

Question 4

List the two types of corneal pain sensation. Can these two co-exist or are they mutually exclusive? Describe what each of these occurs as a result of, and note whether they are acute or chronic.

Answer 4

Nociceptive pain
-occurs in response to actual pain or tissue damage
-typically transient
Neuropathic pain
-occurs as a result of damage to the somatosensory pathway
-more likely to be chronic

Question 5

What three key pieces of information in clinical history would lead a clinician to suspect corneal neuropathy in a dry eye case?

Answer 5

Sensations of heat or prickling
Association with other neuropathic disorders (migraines)

Question 6

What technique can be used for anatomical evaluation in a suspected corneal neuropathy case?

Answer 6

Corneal confocal microscope

Question 7

What two thechniques can be used for functional testing of nerves in a suspected corneal neuropathy case?

Answer 7

Topical anaesthetic (use a grading scale 1-10 before and after)
Scleral lenses (central sensitisation)

Question 8

What are three management options for the treatment of corneal neuropathy?

Answer 8

First-line medications for neuropathic pain
Autologous serum tears
Omega-3 fatty acids

Question 9

List three first-line medications for neuropathic pain.

Answer 9

Tricyclic anti-depressants
Opioids
Opioid-like drugs

Question 10

Is there any evidence that omega-3 fatty acids can be of benefit to nerve health (including corneal nerves)? Does it have any effect on the tear film composition?

Answer 10

Yes, it may improve the health and growth of corneal nerves, and changes the tear film composition

Question 11

Whats better, NITBUT or NaFL TBUT?

Answer 11

NITBUT
Fluorescein should only be used if NITBUT isnt available

Question 12

List 8 triaging questions for a suspected dry eye case.

Answer 12

How severe is the discomfort?
Do you have any mouth dryness or swollen glands?
How long have your symptoms lasted and was there any triggering event?
Is your vision affected and if so, does it get better with blinking?
Are the symptoms/redness worse in one eye?
Do your eyes itch, appear swollen/crusty, or any discharge?
Do you wear contact lenses?
Do you have any general health conditions or are you taking any medications?

Question 13

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

Answer 13

Risk factor

Question 14

What is the cutoff score for DEQ-5 and OSDI?

Answer 14

DEQ-5 - ≥6
OSDI - ≥13

Question 15

What is the cutoff for TBUT?

Answer 15

<10 seconds

Question 16

What is the cutoff for tear osmolarity?

Answer 16

≥308mOsm/L in either eye or interocular difference of >8mOsm/L

Question 17

What is the cutoff for ocular surface staining for the following:
Corneal spots
Conjunctival spots
Lid margin staining

Answer 17

> 5 Corneal spots
9 conjunctival spots
Lid margin staining ≥2mm and ≥25% width

Question 18

List three non-modifiable risk factors for dry eye (excluding systemic conditions).

Answer 18

Age (>40 years)
Female
Asian ethnicity

Question 19

List 5 systemic conditions that are risk factors for dry eye.

Answer 19

Diabetus
Rosacea
Rheumatoid arthritis
Sjögrens syndrome
Thyroid dysorders

Question 20

List 4 modifiable risk factors for dry eye disease (excluding environmental factors).

Answer 20

Medications (ie isotretinoin)
Cigarette smoking
Computer use
Contact lens wear

Question 21

List three modifiable environmental factors for dry eye disease.

Answer 21

Humidity
Air currents/drafts
Air conditioning

Question 22

When should tear osmolarity be measured and why?

Answer 22

After fluorescein (only to be used if NITBUT is unavailable)

Question 23

What may the following scores indicate in a DEQ-5 survey:
≥6
≥12

Answer 23

≥6 - suspicion of dry eye
≥12 - may indicate sjögrens syndrome

Question 24

Describe how NITBUT is carried out, using what, and how many measurements are taken. Does it have good correlation with NaFl TBUT?

Answer 24

Observe reflected placido disc from the pre-corneal tear film
Measure time in seconds until visible distortion of the reflected disc
Use an average of three measurements
Poor correlation with NaFl TBUT

Question 25

Does the reduction in tear osmolarity precede symptomatic improvement or is improvement instant?

Answer 25

It precedes improvement

Question 26

What dye is used to assess conjunctival spots in dry eye assessment?

Answer 26

Lissamine green

Question 27

How does the lid margin appear normally vs abnormally (in dry eye)?

Answer 27

Normal - clear/smooth
Abnormal - scalloped and thickened

Question 28

How does gland expression occur normally vs abnormally (in dry eye)?

Answer 28

Normal - easy
Abnormal - difficult

Question 29

How does gland excretion appear (colour/consistency) normally vs abnormally (in dry eye)?

Answer 29

Normal - liquid and clear
Abnormal thick/pasty and yellow/white

Question 30

What does meibography indicate and what does it mean? What does it correlate with (3)?

Answer 30

Extent of drop-out (% area of eyelid)
Indicates loss of secretory acinar tissue
Correlates with lipid layer thickness, NIBUT and OSDI

Question 31

Is dropout indicated by meibography permanent? What is the % threshold for symptoms (OSDI) for superior and inferior lids?

Answer 31

It is permanent
Superior lid drop-out - 17%
Inferior lid drop-out - 29%

Question 32

What is more typical in dry eye, more superior or inferior lid drop-out?

Answer 32

Inferior > superior loss typical in dry eye

Question 33

What is a normal tear prism/meniscus height?

Answer 33

0.2mm

Question 34

What phenol red thread test measurement would indicate dry eye?

Answer 34

<10mm/15 seconds

Question 35

What is the sensitivity and specificity of the phenol red thread test (high/low)?

Answer 35

High specificity
Low sensitivity

Question 36

What is the sensitivity and specificity of the schirmer I test (high/low) and for what values specifically?

Answer 36

High specificity
High sensitivity
For values <5mm/5mins