Dry Eye Disease Investigations Flashcards
Why is it important to asses tear film?
- Complete tear film is essential for:
o Antibacterial properties – to fight infection
o Transporting nutrients to cornea – cornea is avascular so needs nutrients from somewhere
o Optical performance of eye – if not good tear film then not smooth refraction of light into eye & so blurred vision is symptom of DE – if tear film is damaged then can affect vision overall
o Successful CL wear
o Removing FBs - Dry eye is due to disorder or disturbance of tear film
Describe the structure of tear film?
- Outer oily layer
o Produced by meibomian glands (if have MGD it is lipid layer you lack leading to ↑ evaporation)
o Smoothes tear surface and decreases evaporation - Aqueous (Watery large middle) layer
o Produced by lacrimal gland
o Carries nutrients & oxygen to cornea
o Washes away particles & irritants - Inner mucous layer
o Produced by conjunctiva (in particular goblet cells)
o Provides protection & ensures eye remains moist
o Vital for stability of tear film (vital in ensuring tear film remains on)
Now being described more as a mucin gradient through the tear film
Describe Dry Eye Disease (DED) overall?
- Complex group of conditions
- Characterised by a dysfunction of one or more of components of tear film
- Multifactorial – can be multiple things causing it
- Types:
o Evaporative (e.g. due to MGD)
o Aqueous deficient (e.g. due to age)
o Mixed – both of above
Aqueous deficient px has reduced production of tears
Evaporative px has increased evaporation with normal production of tears
Reduced lacrimal flow but also MGD
What is dry eye caused by?
- Too few tears
o Resulting from:
Nerve damage
Refractive surgery - Too high an evaporation
o Resulting from:
Environment e.g. air con
Lids conditions e.g. bleph - Both of the above causes of DE feed into cycle in same way, both cause hyperosmolarity – in turn releases various inflammatory markers that lead to goblet cell loss & epithelial damage to cornea & apoptosis (cell death)
o These factors cause tear film instability or low tear break-up time
o Tear film instability also causes hyperosmolarity – then stuck in cycle – therefore management is difficult if have to break cycle - Preservative reaction or allergy can also cause tear film instability
What are the risk factors for dry eye?
- Female – especially during menopause – hormonal element
- Age
- Smoking
- Caffeine consumption
- Diabetes mellitus – can be severe
- Topical medications – especially those with preservatives
- Systemic medications
- Acne rosacea – associated w/ MGD
- History of arthritis – any autoimmune conditions e.g. Sjogren’s, Lupus
What is aqueous deficient dry eye (ADDE)?
- ADDE primarily refers to a failure of tear production by the lacrimal gland
- This leads to a reduction in the volume of tears which, in turn, causes hyperosmolarity of the tears due to evaporation
- This hyperosmolarity induces an inflammatory response on the ocular surface
- ADDE can be sub-divided into Sjögren’s syndrome dry eye and non-Sjögren’s syndrome dry eye
Describe aqueous deficient dry eye (ADDE) and Sjogren’s?
- Sjögren’s syndrome is an autoimmune condition involving damage to the secretory glands throughout the body, such as the salivary, vaginal and lacrimal glands.
- Primary form of Sjögren’s syndrome dry eye (SSDE) occurs independently of any other autoimmune condition, but alongside a reduction in saliva production
- Secondary SSDE occurs alongside an autoimmune condition, such as systemic lupus erythematosus or rheumatoid arthritis
Describe aqueous deficient dry eye (ADDE) and non-sjogren’s?
- Acinar atrophy and periductal fibrosis can cause an obstruction affecting tear production scarring in lacrimal gland/duct area – tears then can’t reach surface of eye
- Familial dysautonomia – problems with reflexes throughout body – reflex tearing & normal basal secretion of tears - rare
- Congenital alacrima – rare – absence of lacrimal gland
- Secondary causes include:
o Obstruction of the lacrimal gland ducts from chemical/thermal trauma (scarring)
o Trachoma
o Contact lens wear
o Diabetes
o Cranial nerve damage
o Systemic medication use - Secondary obstruction of the lacrimal gland itself, due to conditions such as lymphoma (cancer), sarcoidosis, graft-versus-host disease and acquired immunodeficiency syndrome
Describe evaporative dry eye (EDE)?
- EDE is a consequence of increased evaporation of tears from the ocular surface, when the lacrimal gland is functioning normally
o Normal level of tears, they are just evaporating too quickly - This increase in tear evaporation leads to tear hyperosmolarity
- EDE can be due to either an abnormality with the ocular structures (intrinsic) or an external factor (extrinsic)
Describe intrinsic evaporative dry eye (EDE)?
- Meibomian gland dysfunction
o Blockages in glands, don’t have lipid layer to protect aqueous which leads to increased evaporation
o Congenital lack, malformation or scarring of the meibomian glands
o Telangiectasia (see in pic) – classic sign of MGD – lots of BVs on inflamed lid - Proptosis – thyroid eye disease -> lid retraction -> exposure of ocular surface leading to increased evaporation
- Low blink rate – commonly when looking at screens
Describe extrinsice evaporative dry eye (EDE)?
- Contact lens wear – piece of plastic disrupting tear film
- Ocular surface disease e.g. allergy – look under eyelids to look for papillae
- Systemic drug use e.g. isotretinoin (Roaccutane – acne tx)
- Topical drug use – anything that’s preserved
- Vitamin A deficiency – may not be as common in UK
- Environment e.g. air conditioning, central heating (low humidity, dry atmosphere)
What questions should be asked in px reporting dry eye?
o Dry eye is chronic problem – rarely acute
* Binocular? Is one eye worse?
o DE is binocular unless really unusual cause – e.g. only wear CL in one eye
o Can be asymmetric
* Describe your symptoms in your own words
o If burny, gritty, firey – then aqueous deficient
o If watery eye – leads down different route
o Gives idea on how effects their life
* What have you tried? How often did you use it? Did it work?
o E.g. drop, gel, hot compress
* Does anything make your symptoms worse/better?
o Anything triggering them e.g. only in work under AC unit
o Anything improve it? – better on holiday = more humidity
* General health – diabetes? Autoimmune conditions?
* Medications?
o Systemic meds – oral contraceptive, beta blockers, antihistamines
o Never advise px to stop using meds – but if tie in start of meds with start of dry eye can communicate to doctor & see if alternative med or if we need to manage the dry eye while they are on the meds
* VDU use? Occupation? CL wearer?
* Allergies?
o Most of these will also be allergic to preservatives
o If px has red watery eye and may be thinking evaporative dry eye – consider allergic conj
May need mast cell stabiliser or antihistamine instead of DE tx
What are the symptoms of Dry Eye Disease?
- Including, but not limited to:
o foreign body sensation
o grittiness
o pain – if corneal involvement
o itching – allergy as differential
o blurred vision
o photophobia – if corneal involvement
o lacrimation
o redness - ADDE: burning, gritty sensation
- EDE: watery, uncomfortable eyes. May be worse in certain environments
- Mucus: sticky, uncomfortable eyes. May report a stringy discharge
o Not as common – may be misdiagnosed as bacterial conj - If the cornea is affected then expect reports of pain, photophobia
o BUT, in long standing severe DED the cornea desensitizes (nerves damaged) so the most severe cases may not report the most severe symptoms
Sxs & signs of DED may mismatch – if lots of damage make sure px understands severity of problem
When and why would you use a symptom questionnaire?
- Complete after H&S
- Gives quantifiable number on symptoms
- Less subjective way to measure symptoms
- 3 main ones:
o Ocular Surface Disease Index (OSDI) – asks about environment px is in
o DEQ-5 – shortest, just 5 Q’s
o McMonnies – asks about meds, swimming, alcohol intake (risk factors) – asks about age and gender as well (age increases so score automatically increases too) - CANNOT SWAP AND CHANGE WHICH ONE USE WITH PX – consistency is key
What is the differential diagnosis of Dry Eye Disease?
- Viral conjunctivitis – due to watery discharge
o Short term, not chronic – usually starts in one eye – other people in household
o Follicular reaction - Bacterial conjunctivitis – sticky discharge
- Allergic conjunctivitis – watery, itchy eye – more chronic when perennial so easily confused
o Papillae reaction - Eyelid abnormality – ectropion, entropion – look for on slit lamp
- Nocturnal lagophthalmos – technically causes dry eye but not a type of dry eye itself – problem with closure of eyelids when sleeping – causing dry eye – tape eyes during night
LID EVERSION is v useful for helping with diagnosis
When do lid eversion in dry eye – usually see redness & roughness rather than follicular or papillae
Describe a watery eye and the tests to determine the cause?
- Could it be problem with lids e.g. ectropion
- Could it be problem with puncta – tears can dry away
- Blocked nasal-lacrimal duct
- Punctal stenosis – puncta becomes too small and tears cant drain
o Important to investigate puncta - Jones’ Dye Test:
o 1 drop of fluorescein 2% into each eye – need 4/5 strips to get conc to this level
o Wait 5 minutes
o Have the patient blow their nose onto a white tissue (one nostril at a time) or have the patient gently insert a cotton bud (soaked in anaesthetic) into the lower part of the nose (latter less done)
Check for NaFl on tissue – if clean then not drained properly
o Also observe the patient, has the fluorescein spilled over onto the cheeks? – eye should be white not yellow after 5 mins - Lacrimal Syringing:
o Used when indicated that something is blocking it and tears aren’t getting through
o This is mostly a diagnostic test but in some pxs this is a management as can sometimes be enough to clear a small blockage
o This is an entry level skill in the UK if take part in training from experienced practitioner or through NES/further courses e.g. IP
o Involves inserting cannula (not a needle) into lower puncta and washing saline through – be clear to px it is NOT a needle
o If the saline comes back up the lower or out the upper puncta then there is a blockage
o Otherwise the patient will taste the saline in the back of their throat and the duct is clear, saline can be enough to clear an obstruction – taste salty
o Tend to anaesthetise px just for discomfort – ‘weird feeling but not painful’
What are the signs of Dry Eye Disease?
- Corneal and conjunctival staining
- Reduced tear break-up time (TBUT) – or reduced tear stability
- Reduced tear production
- Conjunctival hyperaemia and roughening of the surface
- LIPCOF (lid parallel conjunctival folds)
- TMH (tear meniscus height)
- Lid wiper epitheliopathy
What should you assess in the ocular exam of a patient with (potential) dry eye?
use grading scales throughout – makes monitoring easy – same scale for same px
* Lids/lashes – anterior bleph/ MGD/ demodex/ ectropion/ entropion/ trichiasis
o Look at periocular skin too – look for rosacea
* Conjunctiva – bulbar and palpebral, white light and with fluorescein
* Cornea – white light and with fluorescein
* TBUT
* TMH
* Puncta – present? Is it meeting the ocular surface? Does it look open?
Which stain should you use to assess for dry eye?
- Lissamine Green
o Dry eye is >9 punctate spots
o Red filter can help with visualization
o Superior for conj - Fluorescein
o Cobalt blue light – use Wratten filter to help
o Dry eye is >5 punctate spots
o Superior for cornea - Rose Bengal – good stain but v uncomfortable for px
Describe tear production/volume and how this is measured?
- To help us define the type of DED
- Schirmer test (<10mm DED, <5mm query Sjogrens) – within 5 minutes
o Thin piece of filter paper placed into eyelid at outer temporal third
o Quite invasive so last test done on px - Phenol Red Thread (<10mm DED)
o pH test – only in place for 15secs – measure colour change areas after this - Strip Meniscometry
o Placed for 15secs – how far do tears travel down tube – newer test
Describe tear-break up time (TBUT)?
- This can be done invasively (with fluorescein) or non-invasively with keratometry mires (B&L) or a tearscope grid pattern
o Both good – non-invasive preferred but not everywhere has the equipment
o Instilling any amount of NaFl onto ocular surface can add fluid/liquid and increase level of tears and make it look better or it can destabilise tear film due to strip tapped onto ocular surface - What is a normal time?
o FTBUT = >10 seconds
o NITBUT = >15 seconds - Newer technology emerging that allows for automated TBUT assessment – taking subjective element out
Describe tear meniscus height and how to measure it?
- Measurement of tear meniscus height (<0.3mm) – any less than this then dry eye
- Also look at the continuity of the meniscus – should be same all way long – often uneven in DE
- Can be done with a slit lamp – lower beam height – use white light – subjective test
- Newer technology takes out the subjective element
o OCT
o Ocular surface analyser
These both take image of the meniscus & then use a curser to select top & bottom of meniscus and it measures it for you
What is LIPCOF - dry eye?
Lid Parallel Conjunctival Folds
* Approx. 0.1mm in width
* Combine nasal & temp for score
* Assessed without dye
* Should be there all time – not when nudge lids
Degree:
No conjunctival folds: 0
One permanent & clear parallel fold: 1
2 permanent & clear parallel folds: 2
More than 2 permanent & clear parallel folds: 3
What is lid wiper epitheliopathy?
- Alteration in epithelium of advancing lid margin due to friction during lid movement across the lens surface
- Tear film thickness insufficient to separate ocular surface and lid wiper
- Lissamine green staining easier to see this with – could use NaFl but harder
- Look for this when not seeing any other signs of DE on conj or cornea but px still really symptomatic – getting friction/discomfort on blink
What is tear osmolarity? (other test used in diagnosing DE)
- More salty tears are, higher osmolarity
- Completely objective test, instant result
- Requires a tiny sample of tears
- Expensive – individual test cards for each px
- Gives an idea of the level of inflammation in the tears – useful
- Can also be useful before prescribing anti-inflammatory drugs as gives baseline value
- Cut-off for dry eye 308mOsm/l for DE & 316mOsm/l for moderate/severe
- Two main devices
o TearLab collects tears (been around for a lot longer)
o I-Pen presses onto conjunctiva (newer device available)
What is meibography? (other test used in diagnosing DE)
- Imaging the Meibomian glands using IR light
- Can assess the integrity of the glands and look for “drop out”
- Can look for notches on lid margin if there is “drop out”
- Useful for showing to patients
o Explaining that they have lost some glands already & they need to be proactive to maintain other glands – may help compliance - Can be graded manually using the Meiboscore (subjective – approximating % loss) or newer equipment will include an automated grading system to give you a percentage Meibomian gland loss.
What is Inflammadry? (other test used in diagnosing DE)
- Test to see if there is MMP-9 present in the tears.
- Matrix metalloproteinase 9 (MMP-9) is one of the inflammatory biomarkers for dry eye disease.
- Relatively invasive, involves pressing gently onto the bulbar conjunctiva multiple times to collect the tears
- Takes couple minutes to get sample – Total time approximately 15 minutes to get the results
What is Impression Cytology/Tear Sample Analysis? (other test used in diagnosing DE)
- These are much more research type tests at the moment but as with Inflammadry they may be commercialized in future.
- Already talk of a test that will measure other inflammatory biomarkers
- Impression cytology involves taking a sample of cells from the bulbar conjunctiva – invasive – anaesthetised
- Need biological lab for these two tests at the moment
What is Lipid Layer Assessment? (other test used in diagnosing DE)
- Indirect measure of how well the Meibomian glands are functioning
- Becoming more common in practice – devices such as the EasyTearView and the Ocular Surface Analyser
- Good for looking for improvement and showing patients
- What happens when px blinks – do you get even spread of lipid layer across ocular surface with each blink? – or areas of v bright colours which tells lipid layer is v thick – areas of no colour at all which means it is absent
- Common in MGD is poor quality lipids released and they just clump
- Want nice even colours and it spread across eye with each blink
What is Easy Tear View? (other test used in diagnosing DE)
- Clicks onto front of slit lamp – doesn’t take up space
- Allows to do interferometry, automated TMH, NITBUT, Non-Invasive Dehydration Up Time (NIDUT) to evaluate wettability of CLs, Meibography
- Development on from the Tearscope – does more than Tearscope
What is Ocular Surface Analyser? (other test used in diagnosing DE)
- Clicks into slit lamp
- Meibography imaging
- Demodex imaging
- Blepharitis imaging – useful for showing to pxs – good for compliance
- Non-Invasive Break up Time (NIBUT)
- Lipid Layer evaluation -> Interferometry – visualising in vivo the interference fringes of lipid layer in tear film
- Tear Meniscus Height
How do you tell what type of blepharitis a px has?
Staph: crusty
Seborr: greasy
Demodex: collarettes
