CL - Contact Lens Complications - Week -1 Flashcards by Alexander Bowden

What are the 4 broad causes of contact lens complications?

Inflammation (e.g. allergy, immune response)
Mechanical (e.g. rubbing, poor fit)
Microbiological (i.e. infection)
Hypoxia

How well did you know this?

Not at all

Perfectly

What are 6 common risk multipliers for contact lens complications?

dry eye
male
smoker
extended wear
lifestyle
compliance

How well did you know this?

Not at all

Perfectly

What should be covered in the history of a contact lens wearing patient? (10)

PC: VA? Photophobic? Pain?
Red?
Discharge?
Onset + duration?
EW? 
Lens characteristics (type, age, replacement)
Care system (rub/rinse?)
Compliance
GH, Ocular medications (Rx + OTC)
Tap water/swimming/showering

How well did you know this?

Not at all

Perfectly

What 3 dyes can we use to assess ocular surface damage?

Fluorescein (NaFl)
Rose Bengal
Lissamine Green

How well did you know this?

Not at all

Perfectly

What do Rose bengal and lissamine green stain?

damaged cells and devitalized areas of the surface

How well did you know this?

Not at all

Perfectly

Which is more toxic: rose bengal or lissamine green? How can we minimise discomfort for the more toxic dye?

Rose bengal is more toxic to the ocular surface and thus causes stinging. (can use topical anaesthetic to minimise discomfort)

How well did you know this?

Not at all

Perfectly

How should we score ocular conditions on grading scales?

To the first decimal

How well did you know this?

Not at all

Perfectly

How should we manage corneal staining if the cause of staining is infection, toxic, allergic or inflammatory?

treat the overall condition

How well did you know this?

Not at all

Perfectly

How should we manage corneal staining if the cause is hypoxia?

increase Dk/t or decrease WT (wearing time)

How well did you know this?

Not at all

Perfectly

What happens to a CL patient with epithelial loss?

nerve ends get exposed, resulting in pain

How well did you know this?

Not at all

Perfectly

How long does superficial staining of the cornea take to heal? What about deep staining?

Superficial: 24 hours
Deep: 1-2 days

How well did you know this?

Not at all

Perfectly

For how long should a patient cease contact lens wear if they have deep corneal staining?

2-4 days while treating the cause

How well did you know this?

Not at all

Perfectly

How can we manage corneal staining if the stroma is affected?

consider prophylactic antibiotics (CHL 0.5%) (or aminoglycoside for better gram -ve cover)

How well did you know this?

Not at all

Perfectly

How does the eye protect itself from infection? (3)

Cell shedding + wiping action of blnking
Irrigation by lacrimal secretions
Antimicrobial defenses (tear lysosoyme, immunoglobulins, anti-microbial peptides on ocular surface)

How well did you know this?

Not at all

Perfectly

What does PEDAL stand for? (differentiating ulcer vs infiltrate)

Pain
Epithelial defect
Discharge
AC reaction
Location (central/paracentral)
(bonus: lid swelling/oedema)

How well did you know this?

Not at all

Perfectly

How does the staining of an ulcer compare to infiltrate?

Ulcer: 1:1 staining defect/lesion ratio
Infiltrate: small staining

How well did you know this?

Not at all

Perfectly

How does the level of conjunctival infection of an ulcer compare to infiltrate?

Ulcer: generalised conj injection
Infiltrate: sector skewed injection

How well did you know this?

Not at all

Perfectly

How does the number of lesions in an ulcer compare to infiltrate?

Ulcer: usually single lesion
Infiltrate: can be multiple lesions

How well did you know this?

Not at all

Perfectly

What microbe is most commonly responsible for MK?

Pseudomonas

How well did you know this?

Not at all

Perfectly

How does pseudomonas aeruginosa cause damage? (2)

Exotoxins inhibit protein synthesis
Biofilm generation (glycocalyx; polysaccharide)

How well did you know this?

Not at all

Perfectly

Where can you find acanthamoeba? (4)

Soil, air, fresh water, tap water

How well did you know this?

Not at all

Perfectly

What percentage of keratitis is due to acanthamoeba? What percentage of acanthamoeba keratitis is due to contact lens wear?

<1%

85%

How well did you know this?

Not at all

Perfectly

When is acanthamoeba keratitis often diagnosed?

When bacterial management not working (e.g. improving, but never getting better)

How well did you know this?

Not at all

Perfectly

When must you refer any corneal lesion?

when the lesion is on the visual axis

How well did you know this?

Not at all

Perfectly

How can you manage MK?

Fluoroquinolones - g15min loading, then g1hr

In accordance with SCUT: How does high dose steroid treatment affect visual outcomes in patients with culture-positive bacterial keratitis? What was the odds ratio

Better visual outcomes. Odds ratio of better outcomes with high dose steroids was 5.49

In accordance with SCUT (steroids for corneal ulcers trial): what factors were significantly associated with visual outcomes? (5)

``` high-dose steroid treatment visual acuity on presentation age group cause of keratisis infiltrate size/location ```

Are infiltrates unilateral or bilateral

Can be either uni or bi-lateral

Are infiltrates symptomatic?

Can be either

How much epithelial excavation occurs with infiltrate?

only slight excavation

Name 3 possible causes of infiltrates in a contact lens wearer

Poor compliance MG dysfunction/bleph Hypersensitivity (e.g. to lens, solution, bacteria)

How can we treat infiltrates? (4) When should we review? (1)

``` Cease lens wear Steroid/antibiotic Change lens type/modality/WT/replacement If suspect infection - tx as infection Review 24 hours ```

What is CLARE? What patients is it common in?

Contact Lens Acute Red Eye: immune response to acute or chronic hypoxia. Common in EW patients

Can CLARE present with bacterial presence?

yes. May or may not have presence of high bacterial load on the contact lenses that is being trapped in close proximity to the ocular surface

How may tight lenses contribute to bacterial accumulation in CLARE?

no tear exchange to flush toxins

List 5 signs of CLARE

``` Painful red eye +/- photophobia Diffuse + focal infiltration Corneal epithelial + stromal oedema Conj + limbal oedema, injection Peripheral, multiple? culture negative infiltrates ```

How do we manage CLARE? (2)

Cease lens wear | Consider steroid with or without antibiotics?

How does GPC occur?

mechanical irritation/inflammation/allergic response

What is GPC associated with? (5)

``` Soft (5-10%)/RGP(3-5%) CLs Prosthetic devices Exposed sutures Glaucoma filtering blebs Corneal scars ```

What are papillae? Where are they mainly located? Where do they first appear?

Hyperplastic conjunctival epithelium Mostly in upper palpebral conjunctiva First appear at margin of tarsal plate

What are the major causes of papillae? (2)

CLPC (contact lens induced papillary conjunctivitis) | Vernal conjunctivitis

What are follicles? Where are they mainly located?

Hyperplastic lymphoid tissue | Mostly found in inferior forniceal conjunctiva

What are the major causes of follicles? (2)

Viral infection | Hypersensitivity to solutions

How can you tell follicles and papillae apart?

Follicles: encircled by vessels, rice grain appearance Papillae: central tufts of vessels, appear like cobblestones

How can we treat CLPC (CL induced papillary conjunctivitis)? (3)

Cease lens wear Preservatives free cleaners/frequent lubrication Reduce protein exposure (change to daily disposable if SCL, or in-office lens surface polish for RGPs and increased frequency of protein removal for any CL)

How long may grade 3-4 CLPC take to treat? What happens if left untreated for many years?

1-6 months. If untreated, you'll get conjunctival scarring

Name 6 mechanical complications from contact lens wear?

``` FB staining (RGP >>> SCL) RGP and SCL binding Epithelial wrinkling (thin, high water SCL) Bubble indentations (RGP fit issue) Mucin balls SEALS ```

What are SEALS? Who is affected by them?

Superior Epithelial Arcuate Lesion. Affects SCL wearers (more commonly Si-H)

List 2 signs of SEALs

Epithelial split | Staining with Nafl

What causes SEALS? (3)

lens thickness modulus lid force (tight lids?)

How can you treat SEALS? (3)

Discontinue wear until resolves (~1-2wks) Change SCL design (softer modulus) Change to RGPs

How do mucin balls form? Are they punctate staining?

Form via interaction of lens surface and corneal epithelium in higher modulus lenses. - They are NOT punctate staining. They are indentations

What complications arise from hypoxia in contact lens wearers? (6)

Epithelial cell loss, microcysts + vacuoles Stromal transparency, striae + folds Endothelial blebs, polymegathism, pleomorphism + bedewing Neovascularization Corneal exhaustion syndrome Superior limbic keratoconjunctivitis (SLKC)

What causes neovascularisation? (4)

Chronic oedema Stromal softening Mechanical irritation Inflammatory response

Where is neovascularisation located in contact lens wearers?

located near the source of irritation (often superior lid)

What are microcysts? What contact lens problem are they associated with and when are they seen?

Pockets of cellular debris in the epithelium. Associated with days-wks of hypoxia. Now only seen in EW patients.

List 3 signs of microcysts

small inclusions in epithelium at 40x mag Presence of a few microcysts is normal Small NaFl stain only when they reach the epithelial surface

How can you manage microcysts? (3)

Improve Dk/L? Decrease WT (wearing time) Reduce or cease EW

How can you differentiate microcysts from vacuoles?

In retroillumination: MR UV Microcysts reversed: shadow away from darkness Unreversed Vacuoles: shadow towards darkness

How does the stroma present with 5-6% swelling? What about 10-12%?

5-6%: Striae | 10%: Folds

Does polymegathism and pleomorphism of the endothelium in response to contact lens hypoxia occur after a short time or long time?

occurs as a chronic response to hypoxia (years)

How can we manage hypoxia? (3)

Increase Dk/L (increase dk or decrease lens thiccness) Improve tear exchange (RGPs) Reduce wearing time

What are the critical cornea O2 requirements for contact lens wear for daily wear and extended wear?

Daily wear: Dk/t of 24 (avoids oedema) | EW: Dk/t of 87 (limits to 4% oedema)