12. DED Diagnosis I

Question 1

The ... is responsabile for tear production, ... and .... This includes the ..., ..., ..., ... and .... ... mediates rate and ... of tears produced. ... have natural feedback loop, whereas ... is caused by a stimulus.

Answer 1

The lacrimal functional unit is responsabile for tear production, distribution and clearance. This includes the lacrimal gland, ocular surface components, meibomian glands, eyelids and associated sensory and autonomic nerves. Neural input mediates rate and type of tears produced. Basal tears have natural feedback loop, whereas reflex tears is caused by a stimulus.

Question 2

Dry eye is a ... of the ocular surface, characterised by a ... of the tear film, and accompanied by ..., in which ... and ..., ocular surface ... and ..., and ... abnormalities play aetiological roles.

Answer 2

Dry eye is a multi factorial 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 3

Describe the prevalence of dry eye disease in Australia.

Answer 3

3.5m dry eye suffers in Australia.
2:1 women > men.
Prevalence increases with age.
Affected by systemic medications (anti-depressants, oral contraceptives, doxycycline) and the environment.

Question 4

Evaporative dry eye (EDE) make up ...%, whereas aqueous deficient dry eye (ADDE) make up ...%.
EDE is related to changes in the ... or the .... It is associated with .... This causes an ....
ADDE is relatively more .... It is a result of increased ... of the tears, causing damage to ... and ..., resulting in .... ADDE can be associated with .... ... can be affected, causing reduced ....

Answer 4

Evaporative dry eye (EDE) make up 85%, whereas aqueous deficient dry eye (ADDE) make up 15%. EDE is related to changes in the lipid layer or the meibomian glands. It is associated with meibomian gland dysfunction. This causes an unstable tear film. ADDE is relatively more challenging to manage. It is a result of increased hyperosmolarity of tears, causing damage to epithelial cells and goblet cells, resulting in tear film instability. ADDE can be associated with autoimmune diseases. Lacrimal glands can be affected, causing reduced lacrimal secretions.

Question 5

Patient with DED may be ... or .... Symptomatic patients have signs of .... This normally requires .... However, if patients have ... which impedes them from noticing symptoms, ... will be needed. Symptomatic patients may not present with signs of .... This indicates that patient may be in a ..., therefore should be observed for ... and offered ... if needed. Some patient may be experiencing ..., therefore should be referred for .... Patient who are symptomatic and have signs of ocular surface diseases should be ....

Answer 5

Patient with DED may be asymptomatic or symptomatic. Symptomatic patients have signs of ocular surface disease. This normally requires preventative managements. However, if patients have neurotrophic conditions which impedes them from noticing symptoms, DED management will be needed. Symptomatic patients may not present with signs of ocular surface abnormalities. This indicates that patient may be in a pre-clinical state, therefore should be observed for any future changes and offered preventative therapy if needed. Some patient may be experiencing neuropathic pain, therefore should be referred for pain management. Patient who are symptomatic and have signs of ocular surface diseases should be properly differentially diagnosed and managed accordingly.

Question 6

What are the 4 main aetiological categories of DED?

Answer 6

• Lipid abnormality (most common)
• Reduced aqueous production (can be due to lacrimal gland dysfunction, or secondary to abnormal neural reflex or control)
• Mucin deficiency (least common, due to goblet cell dysfunction)
• Eyelid an blink abnormality (neural or structural)

Question 7

What features can cause lipid abnormalities of the tear film? (3 points)

Answer 7

• Meibomian gland dysfunction
• Systemic or topical drugs e.g. doxycycline, acutane, hormonal OCP, chemotherapy drugs
• Eyelid inflammation or trauma e.g. telangiectasia, MG drop out, notches

Question 8

What features can cause reduce aqueous production? (7 points)

Answer 8

• Autoimmune diseases e.g. Primary Sjogren’s syndrome
• Secondary Sjogren’s e.g. rheumatoid arthritis
• Systemic or topical drugs e.g. anti-histamines (claratine), decongestants, beta-blockers, anti-depressants etc.
• Hormonal changes
• Lacrimal gland (tumours, inflammation, trauma)
• Lacrimal function unit (neural dysfunction)
• Corneal neuropathy → reduction in nerves, therefore reduced signals to produce more aqueous from the lacrimal glands

Question 9

What features can cause mucin deficiencies? (3 points)

Answer 9

• Vit A deficiency
• Systemic or topical drugs
• Severe ocular surface inflammation/ trauma e.g. chemical injury damaging conjunctival goblet cells.

Question 10

What features can cause eyelid and blink abnormalities? (2 points)

Answer 10

• Eyelid malposition → exophthalmos (proptosis), ectropion, entropion, lagophthlmos, Bell’s palsy
• Blink abnormalities → Bell’s palsy, concentrated visual tasks, coma, Parkinson’s disease

Question 11

What other predisposing conditions may cause dry eyes? (apart those that affect lipid composition, aqueous production, mucin and eyelid/ blink abnormalities)? (5 points)

Answer 11

• Contact lens wear
• Topical medications (BAK)
• Filtering blebs
• Pterygia/ pingueculae
• Trachoma & other scarring

Question 12

What is MADE (Mask Associated Dry Eye)?

Answer 12

Wearing masks causes air to be breathed up and out of the face mask, causing concentrated air to run over the ocular surface. Movement of air over the eye causes tears to evaporate, leaving the surface of the eye dry.

Question 13

What is the 3 steps of the TFOS DEWS II diagnostic algorithm?

Answer 13

1. Trigaging questions
2. Risk factor analysis
3. Diagnostic tests

Question 14

What are the triaging questions that should be asked throughout history taking for suspected DED?

Answer 14

• How severe is the eye 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 does it clear on blinking?
• Are the symptoms or any redness much worse in one eye than the other?
• Do you wear CLs?
• Do the eyes itch, are they swollen, crusty, or have they given off any discharge?
• Have you been diagnosed with any general health conditions?
• Are you taking any medications?

Question 15

What are the non-modifiable risk factors of DED?

Answer 15

• Age (>40 yo)
• Female sex
• Asian ethnicity
• Systemic conditions e.g. diabetes mellitus, rosacea, rheumatoid arthritis, Sjogren’s syndrome, thyroid disorders

Question 16

What are the modifiable risk factors of DED? (5 points)

Answer 16

• Medications
• Cigarette smoking (proinflammatory)
• Computer use
• Contact lens wear
• Environmental factors (humidity, air currents/ drafts, air conditioning)

Question 17

Diagnostic tests for DED starts off with screening, which involves testing for symptoms using ... or .... Only ... provides measure of severity and help monitor patients over time. For each test, scores of ... >= ... or .... >= ... are threshold. In order to be diagnosed with DED, passing threshold scores plus at least ... of the homeostatic markers must be present. There are 3 homeostatic markers: ... (...) should be less than ... seconds; ... with >= ...m0sm/L in either eye or interocular difference >... m0sm/L; Ocular surface staining with ... (>... corneal spots) or with ... (>... conjunctival spots) or ... staining (>=...mm length & >=...% width). Afterwards, further testing is needed in order to ....

Answer 17

Diagnostic tests for DED starts off with screening, which involves testing for symptoms using DEQ-5 or OSDI. Only OSDI provides measure of severity and help monitor patients over time. For each test, scores of DEQ-5 >= 6 or OSDI >= 13 are threshold. In order to be diagnosed with DED, passing threshold scores plus at least one of the homeostatic markers must be present. There are 3 homeostatic markers: non-invasive tear breakup time (NIBUT) should be less than 10 seconds; tear osmolarity with >= 308m0sm/L in either eye or interocular difference >8m0sm/L; Ocular surface staining with NaFl (>5 corneal spots) or with Lissamine green (>9 conjunctival spots) or lid margin staining (>= 2mm length & >= 25% width). Afterwards, further testing is needed in order to classify whether which type of dry eye it is e.g. evaporative or aqeuous deficiency or combination of both.

Question 18

How is dry eye severity assessed?

Answer 18

Overall severity of DED is more of a subjective clinical judgement. There are not a lot of evidence to have clear cutoffs for severity grading.

Question 19

What are the common dry eye symptoms? (9 points)

Answer 19

• Stinging/ Burning sensation
• Dry eyes
• Gritty/ sandy eyes
• Red eyes
• Watery eyes
• Photophobia
• Tired eyes or eye fatigue
• Difficulty wearing CLs
• Filmy vision
* Symptoms are usually bilateral but can be asymmetric; Symptoms are usually worse in hot, dry, smoky, windy environments.

Question 20

Ocular Surface Disease Index (OSDI) survey is a ... item survey used to quantify dry eye symtoms over the ..., relating to ..., ... and .... Scores stratifies ...;
DEQ-5 survey is a ... item survey used to capture information over the ... relating to frequency of ..., ..., ... during the day. Scoring of >= 6 indicates ...;
Score of >= 12 indicates .... The higher the score, ....

Answer 20

Ocular Surface Disease Index (OSDI) survey is a 12 item survey used to quantify dry eye symtoms over the past week, relating to vision-related functional impact, symptom frequency and ocular response to environmental risk factors. Scores stratifies symptom severity;
DEQ-5 survey is a 5 item survey used to capture information over the past month relating to frequency of watery eyes, eye discomfort, intensity of dryness during the day. Scoring of >= 6 indicates suspicion of dry eyes; Score of >= 12 indicates possible Sjoren's syndrome. The higher the score, the more severe the dry eyes.

Question 21

Compare and contrast non-invasive breakup time and fluorescein tear breakup time. Why is NIBUT preferred?

Answer 21

Tear instability is a major feature of all forms of dry eye disease.
• NIBUT involves observing a reflected concentric placedo ring from the pre-corneal filim. NIBUT measures the time (s) it takes for visible distortions to appear on the reflected target. An average of 3 measures are taken. NIBUT <10 is indicates posible dry eyes. There is high sensitivity (true positive) and high specificity (true negative) rates.
• NaFl can destabilise the tear filim itself. NaFl TBUT has poor reproducibility due to change in volume and pH. There is also lower diagnostic accuracy compared to NIBUT. There is also poor correlation between NIBUT and TBUT.

Question 22

Tear osmolarity is an ... measure of tear quality. Tear osmolarity measures ..., where dry eye patients will have .... Solutes are ..., therefore can lead to ... changes to the corneal and conjunctival .... This test can be used to monitor .... Studies have found that reduction in osmolarity precedes .... Tear osmolarity of >= ... m0sm/L in either eye or interocular difference of >... m0sm/L indicates possible dry eyes.

Answer 22

Tear osmolarity is an objective measure of tear quality. Tear osmolarity measures tear solute concentration, where dry eye patients will have hyperosmolar tears. Solutes are proinflammatory, therefore can lead to morphological and biochemical changes to the corneal and conjunctival epithelium. This test can be used to monitor treatment effects. Studies have found that reduction in osmolarity precedes symptomatic improvements. Tear osmolarity of >= 380 m0sm/L in either eye or interocular difference of >8 m0sm/L indicates possible dry eyes.

Question 23

Describe the steps of NaFl instillation for corneal staining.

Answer 23

1. Wet single paper strip with saline
2. Shake off excess
3. Instill a minimum amount of NaFl
4. Wait 1-3 mins
5. Use Wratten filter to assess staining

Question 24

Describe the steps of Lissamine Green instillation for conjunctival and lid wiper staining.

Answer 24

1. Use 2 drops from 2 paper strips to instill lissamine green, 1 min apart
2. Wait 1-4 mins post-instillation
   *If using fluorescein as well, wait 3-5 mins
   * Avoid touching the lid wiper area while everting the lids