Lecture 10 contact lenses and dry eye Flashcards

1
Q

What does a contact lens separate the tear film into?
What is each part associated with?

A

-pre-lens tear film: lens fit and movement

-post-lens tear film: comfort as it interacts with lids. Associated with drying/deposits.
-helps posterior lens lubrication.

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2
Q

What part of the tear film does the CL sit in?

A

aqueous tear film

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3
Q

Why shouldn’t tears be static in contact lens wear?

A

Tear exchange in important for removal of tear debris and metabolic by-products

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4
Q

How can a contact lens effect the tear film?

A

*Change in tear production (may be temporary)
*Tear film instability and evaporation
-related to lipid layer and initial tear film thickness. Layers split in 2 so is thinner.
-visual acuity may fluctuate
*Effect on tear film mucins, electrolytes and increase osmolarity
-reduced mucin so increased friction
-higher osmolarity associated with dry eye
*Blinking

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5
Q

What must you examine in the assessment of the tear film?

A

GLANDS-secretion, expression and blockages
LIDS AND LASHES- disease, position, blink rate
TEARS- volume, tear prism height, TBUT, quality, osmolarity
OCULAR SURFACE- staining, inflammation, redness

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6
Q

What is the purpose of the phenol red test?
How is it carried out?

A

-tests quantity of tears (aqueous production)

-a thread impregnated with phenol red is hooked on one side of the eyelid from lateral canthus
-important for thread not to touch the cornea as this will cause reflex tearing
-thread is yellow but becomes red when its wet with the tear film
-the test takes 15 seconds
-less than 9mm means dry eyes

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7
Q

What is the purpose of the Schirmer test?
How long does it take?
Why is phenol red thread test better?

A

-tests quality of tears
-5 minutes

-strip in schirmer test can feel uncomfortable and stimulate reflex tearing giving inaccurate tests

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8
Q

How does the tearscope work?

Give examples

A

*Produces a diffuse white reflection over the whole of the cornea using a cold cathode light source.
*Helps practitioner assess the lipid layer of the tear film.
*Flexible inserts can be placed inside the illumination tube to assess corneal distortion and damage.

oculus keratograph 5M- topographer, can examine meibomian glands, non-invasive TBUT
lipiview- can measure lipid layer thickness
inflammaDry- detects inflammatory markers of dry eye disease
tearLab-tear osmolarity- indicates osmolarity abnormalities

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9
Q

What can cause contact lens-related dry eye?

A

*If anterior surface is dry (not well lubricated cornea or not covered well), a portion of the eyelid rubs against it.
*Particularly the area near the eyelid margin
*Tear film thickness is too thin in CL wear to separate ocular surface and lid wiper.
*CL causes alteration in epithelium due to friction

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10
Q

What causes lid wiper epitheliopathy?
How can you assess it?
What is the treatment?

A

■Lid wiper is the area of epithelium in contact with the contact lens and wipes across the contact lens/eye

■Will need to evert lids to examine fully
■Stains best with lissamine green

■Treatment: lubricating eyedrops to achieve better lubrication of eye surface and reduce friction. Review to check if staining has reduced

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11
Q

What are lid parallel conjunctival folds (LIPCOF)?
What causes it?
What is the treatment?
How can it be graded?

A

*Breakdown/decrease in elastic fibres in the loose conjunctiva
*Conjunctival looseness

*Ageing or mechanical forces between conjunctiva and lower lid can cause it
*Tear deficiency and inflammation of the conjunctiva can cause it

*manage tear quality issues and rewetting drops

grade 0: no conjunctival folds
grade 1: one permanent and clear parallel fold
grade 2: two permanent and clear parallel folds (less than 0.2mm)
grade 3: more than two permanent and clear parallel folds (more than 0.2mm)

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12
Q

Why can Meibomian glands cause dry eye?

A

*Blocked glands reduce lipid quality of tears so they are more prone to evaporation

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13
Q

How can lifestyle cause dry eye?

A

*Computer vision syndrome (CVS)
*Prolonged computer, tablet, phone use
*Eye discomfort and visual problems
*Dry eyes related to blinking

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14
Q

What is the resting blink rate?
What can affect blinking?
why does blink rate matter in dry eye disease?

A

around 12x a minute

*Blink rate may change depending on activity, on cognitive or emotional function
*Increases when engaged in conversation
*When focusing on a specific visual task the blink rate may drop (CVS, 60% less blinking)
*Some diseases (e.g., Parkinson’s and schizophrenia) and medications may affect blinking

*Reduced blink rate means tear film is replenished less frequently and evaporates quicker causing ocular discomfort

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15
Q

What are the solutions for reduced blink rate?

A

*Can try blinking exercises
*20-20-20 rule
*Increase tear break up time

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16
Q

How can you manage dry eye in practice?

A

*Lens changes
*Changes to environment
*Eye drops: lubricants, lipid specific products
*Lid hygiene: lid cleansing, heat
*Diet
*MAKE SURE TO REVIEW PX

17
Q

How can the environment cause dry eye?
How can you manage this?

A

*Contact lens discomfort increased by:
-low humidity, increased evaporation from lens
-increased airflow: change direction of blowers in the car

18
Q

How can diet improve dry eye?

A

*Essential fatty acids are understood to enhance lipid layer of tear film-reducing evaporation
*Omega 3 – anti-inflammatory properties (avocados, walnuts, fish, plant oils)
*Omega 6 - pro-inflammatory properties
*Too much consumption of omega 6 may negate the effects of omega 3

19
Q

What are the ideal properties of eye drops?

A
  • Immediate relief
  • Prolonged effect
  • Non-toxic
  • Doesn’t blur vision
  • Inexpensive
    *Higher artificial tear viscosity means tear retention time is increased and might help protect the ocular surface
    *Better for overnight

-Check compatibility with contact lenses
-Recommend preservative free drops
-Ensure no other cause of symptoms like poor lens fit

20
Q

What is the aim of warm compresses?
How should you do warm compresses?

A

*Aim of therapy is to melt the meibum to allow it to be expressed and to prevent obstruction of the terminal ducts.
-helps to alleviate evaporative dry eye?

*Temperature should be monitored, maintained for 10 minutes
*Eye bags more effective as it maintains the temperature
*Do not want to burn the eyes want to melt the meibum within the glands

21
Q

How can you carry out lid hygiene?

A

*Lid cleaning solution with a cotton bud or cotton wool pad
*Clean lid margins (not beyond the mucocutaneous junction)
*2x daily; reduce to 1x daily as condition improves
*Use firm pressure with cotton bud to express glands
*Warm compresses to loosen collarettes and crusts. Use bephasol after this.
*Avoid use of cosmetics, especially eye liner and mascara

22
Q

What is blephex?

A

*Physical debridement of top and bottom lids to remove the collarettes
*Useful in severe anterior blepharitis
*Requires a series of follow up treatments and use of lid hygiene to help reduce re-occurrence