Week 3 - Dry eye disease investigations Flashcards
A complete tear film is essential for:
- Antibacterial properties
- Transporting nutrients to the cornea
- Optical performance of the eye
- Successful contact lens wear
- Removing foreign bodies
Definition
“Dry eye is a multifactorial disease of the ocular surface characterized 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 etiological roles”
Risk Factors
- Female
- Age
- Smoking
- Caffeine consumption
- Topical medications
- Systemic medications
- Diabetes mellitus
- Acne rosacea
- History of arthritis
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 nonSjögren’s syndrome dry eye
ADDE - Sjögrens
- 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
ADDE – Non-Sjögrens
- Acinar atrophy and periductal fibrosis can cause an obstruction affecting tear production
- Familial dysautonomia
- Congenital alacrima
- Secondary causes include obstruction of the lacrimal gland ducts from chemical/thermal trauma and trachoma, contact lens wear, diabetes, cranial nerve damage and systemic medication use
- Secondary obstruction of the lacrimal gland itself, due to conditions such as lymphoma, sarcoidosis, graft-versus-host disease and acquired immunodeficiency syndrome
Evaporative Dry Eye (EDE)
- EDE is a consequence of increased evaporation of tears from the ocular surface, when the lacrimal gland is functioning normally
- 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)
EDE – Intrinsic
- Meibomian gland dysfunction (congenital lack, malformation or scarring of the meibomian glands)
- Proptosis
- Low blink rate
EDE – Extrinsic
- Contact lens wear
- Ocular surface disease e.g. allergy
- Systemic drug use e.g. isotretinoin
- Topical drug use
- Vitamin A deficiency
- Environment e.g. air conditioning, central heating
DED History & Symptoms
- How long for?
- Binocular? Is one eye worse?
- Describe your symptoms
- What have you tried? How often did you use it? Did it work?
- Does anything make your symptoms worse/better?
- General health – diabetes? Autoimmune conditions?
- Medications?
- VDU use Occupation? CL wearer?
- Allergies?
Symptoms of DED
Including, but not limited to:
• foreign body sensation
• grittiness
• pain
• itching
• blurred vision
• photophobia
• lacrimation
• redness
Symptoms of DED (ADDE vs EDE)
ADDE: burning, gritty sensation
EDE: watery, uncomfortable eyes. May be worse in certain environments
Mucus: sticky, uncomfortable eyes. May report a stringy discharge
If the cornea is affected then expect reports of pain, photophobia
BUT, in long standing severe DED the cornea desensitizes so the most severe cases may not report the most severe symptoms
Differential Diagnosis
- Viral conjunctivitis
- Bacterial conjunctivitis
- Allergic conjunctivitis
- Eyelid abnormality
- Nocturnal lagophthalmos
What is jones’ dye test
Jones’ Dye Test
- 1 drop of fluorescein 2% into each eye
- Wait 5 minutes
- 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
- Also observe the patient, has the fluorescein spilled over onto the cheeks?
Lacrimal syringing
- This is an entry level skill in the UK if you take part in training from an experienced practitioner or through NES/further courses e.g. IP
- Involves inserting a cannula (not a needle) into the lower puncta and washing saline through
- If the saline comes back up the lower or out the upper puncta then there is a blockage
- 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
Signs of DED
- corneal and conjunctival staining
- reduced tear break-up time (TBUT)
- reduced tear production
- conjunctival hyperaemia and roughening of the surface
- LIPCOF (lid parallel conjunctival folds)
- TMH (tear meniscus height)
- lid wiper epitheliopathy
Ocular Exam for dry eye
- Lids/lashes – anterior bleph/ MGD/ demodex/ ectropion/ entropion/ trichiasis
- 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?
Tear Film Break-up Time
- This can be done invasively (with fluorescein) or non-invasively with keratometry mires (B&L) or a tearscope grid pattern. Which one is better?
- What is a normal time?
- FTBUT = >10 seconds
- NITBUT = >15 seconds
- Newer technology emerging that allows for automated TBUT assessment
Tear Production/Volume
tests
- To help us define the type of DED
- Schirmer test (<10mm DED, <5mm query Sjogrens)
- Phenol Red Thread (<10mm DED)
- Strip Meniscometry
Tear Meniscus Height
- Measurement of tear meniscus height (<0.3mm)
- Also look at the continuity of the meniscus
- Can be done with a slit lamp
- Newer technology takes out the subjective element
- OCT
- Ocular surface analyser
LIPCOF
Lid parallel conjunctival folds
Approximately 0.1mm in width
Combine nasal and temp for score
Assessed without dye
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”
Osmolarity
- Completely objective test, instant result
- Requires a tiny sample of tears
- Expensive
- Gives an idea of the level of inflammation in the tears
- Debate about the cut-off for dry eye, DEWS II says 308 mOsm/l for dry eye and 316 for moderate/severe
Meibography
- Imaging the Meibomian glands using IR light
- Can assess the integrity of the glands and look for “drop out”
- Useful for showing to patients
Inflammadry
- 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
- Total time approximately 15 minutes to get the results
Impression Cytology/Tear Sample Analysis
- These are much more research type tests at the moment but as with Inflammadry they may be commercialized in the future.
- Already talk of a test that will measure other inflammatory biomarkers
- Impression cytology involves taking a sample of cells from the conjunctiva – invasive.
Lipid Layer Assessment
- 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
Ocular Surface Analyser
“The OSA easily and efficiently integrates the following complex examinations, providing the user with an easy to use ‘traffic light’ results report:
- Meibography imaging
- Demodex imaging
- Blepharitis imaging
- Non Invasive Break up Time (NIBUT)
- Lipid Layer evaluation
- Tear Meniscus Height”
