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Contact lenses year 3 > infective and non infective keratitis > Flashcards

infective and non infective keratitis Flashcards

1
Q

what is a infective keratitis also referred to as

A

microbial

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2
Q

what is a non infective keratitis also referred to as

A

sterile

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3
Q

what are corneal infiltrates

A

an accumulation of inflammatory cells/white blood cells in corneal tissue as part of the body’s inflammatory response to the presence of bacterial toxins

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4
Q

what is the appearance of corneal infiltrates

A

a white/grey appearance which does NOT break through the corneal epithelium

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5
Q

what will not happen as a result of infiltrates not breaking through the corneal epithelium

A

they wont stain with fluorescein, therefore it is a good way of telling if its an infiltrate or something more worse such as an ulcer breaking through the corneal epithelium

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6
Q

what are not all corneal infiltrative events CIE

A

not all are microbial keratitis

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7
Q

what are all microbial keratitis cases called

A

cornel infiltrative events

any keratitis is called a corneal infiltrative event

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8
Q

what can some corneal infiltrates turn into

A

defects which have turned into ulcers

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9
Q

what is a corneal ulcer

A

an epithelial defect with underlying inflammation

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10
Q

what will be the ddx check between corneal infiltrates and corneal ulcers

A

a fluorescein stain check

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11
Q

where will corneal infiltrates form and why

A

in the peripheral cornea

as blood vessels are near the limbus and the cornea is avascular which is better for it to be in the periphery

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12
Q

what can sterile non-infective inflammation of the cornea not be attributed to

A

to one specific cause

it has many different triggers

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13
Q

list 4 possible triggers of a sterile non-infective inflammation of the cornea and what increases the likelihood of all these triggers

A
  • trauma
  • toxicity
  • immune response
  • hypersensitivity

contact lens wear increases likelihood of all these triggers

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14
Q

what happens to the corneal cells which causes sterile non-infective inflammation of the cornea

A

they become distressed, release chemical agents which lead to inflammatory response

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15
Q

explain how trauma is a trigger which can cause sterile non-infective inflammation of the cornea

A

Hypoxic cornea (e.g. sleeping in contact lenses) makes the cornea more vulnerable, more fragile and slow to repair (due to less tear exchange and less oxygen getting to the eye). Mechanical insult may be induced during lens insertion/removal (i.e. if being too rough), Hypoxia may also cause blood vessels to dilate and inflammatory cells to escape more easily

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16
Q

explain how solution toxicity is a trigger which can cause sterile non-infective inflammation of the cornea

A

especially from contact lens solution containing thimerosal or chlorhexidine

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17
Q

explain how lens deposits is a trigger which can cause sterile non-infective inflammation of the cornea

A

from Proteins, lipids etc.

Epithelial distress may also be induced from dead epithelial cells and debris trapped under immobile EW lens

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18
Q

list 5 causes of a infective ulcer

A
  • bacteria
  • fungus
  • virus
  • parasite
  • autoimmunity
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19
Q

how fast can an infective ulcer progress and what implication does this have

A

as fast as 12-24 hours
can cause visual loss
must refer immediately to an ophthalmologist

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20
Q

what damage can a infective ulcer in the case of microbial involvement cause to the ocular structure

A

excavation of the corneal stroma which can lead to an anterior chamber response of flare

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21
Q

what are the 3 various classification systems proposed on the ddx/diagnosis of a corneal ulcer

A
  • ulcerative vs non ulcerative
  • suppurative vs nonsuppurative (whether it produces discharge/pus or not)
  • central vs peripheral keratitis
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22
Q

list 3 reasons why the classification system of ulcerative vs non ulcerative is not a good indicator of an infective ulcer

A
  • Some ulcers are culture-negative i.e. there are some non infective keratitis which does have an ulcer and so you do need to still refer
  • Lack of agreement over definition of an ‘ulcer’
  • Variations in size, the presence of other signs
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23
Q

why is the classification system of suppurative vs nonsuppurative not a good indicator of an infective ulcer

A

because there are reports where microbial keratitis has been diagnosed without any discharge

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24
Q

why is the classification system of central vs peripheral keratitis not a good indicator of an infective ulcer

A

it is not a good indicator as to whether the infiltrate is sterile or not

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25
Q

what are asymptomatic infiltrates

A

infiltrates in patients without any further signs or symptoms

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26
Q

who may asymptomatic infiltrates be present in and what can be the cause

A
  • in non CL wearers as well as CL wearers
  • likely to be induced by environmental factors such as air pollution
  • px is not bothered as they’re asymptomatic and the inflammatory cells will be small
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27
Q

what are the 4 signs of asymptomatic infiltrates

A

1 or more small (less than 0.2mm) discrete grey-White patches usually in the periphery, but can be anywhere on the cornea

They are usually intraepithelial and occasionally subepithelial so it will not stain

Formed from inflammatory cells

No other signs of inflammation i.e. No cells in anterior chamber

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28
Q

what are the symptoms of asymptomatic infiltrates

A

none

hence asymptomatic

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29
Q

what other condition can asymptomatic infiltrates be a mild form of

A

CLARE

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30
Q

what are the 2 management steps of asymptomatic infiltrates

A
  • Px lens care regime and compliances should be checked

- Perhaps review, but may texts recommend no further management required

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31
Q

what is a more serious version of asymptomatic infiltrates

A

asymptomatic infiltrative keratitis

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32
Q

what is asymptomatic infiltrative keratitis

A

an inflammatory event characterized by infiltration of the cornea without patient symptoms

has a similar presentation to asymptomatic infiltrates

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33
Q

what are the 5 signs of asymptomatic infiltrative keratitis

A
  • Small focal infiltrates
  • Up to 0.4mm (larger than asymptomatic infiltrates)
  • Sub epithelial
  • May be small punctate staining
  • Mild to moderate limbal and/or bulbar redness
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34
Q

what are the 4 management steps of asymptomatic infiltrative keratitis

A
  • Cease CL wear
  • Review px
  • Prophylactic antibiotic possibly required
  • Advise against EW (to avoid a hypoxic environment for the cornea)
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35
Q

what is infiltrative keratitis

A

An inflammatory reaction of the cornea characterized by anterior stromal infiltration, with or without epithelial involvement, in the midperiphery to periphery of the cornea

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36
Q

what are the 4 signs of infiltrative keratitis

A
  • Single (in some cases multiple) small round infiltrates in epithelium or anterior stroma
  • May be unilateral or bilateral
  • Sectorial bulbar and/or limbal hyperaemia
  • Epithelium generally does not stain
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37
Q

which condition is the signs of infiltrative keratitis similar to and therefore what will you have to go by to ddx

A

asymptomatic infiltrative keratitis, so have to go by the patients symptoms

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38
Q

what are the 4 symptoms of infiltrative keratitis

A
  • Discomfort, FB sensation, irritation
  • Hyperaemia
  • Possible mild photophobia
  • lacrimation
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39
Q

when may a patient be asymptomatic in infiltrative keratitis

A

when the infiltrates are minor

40
Q

when do symptoms of infiltrative keratitis reduce

A

on lens removal

41
Q

what are the 7 management steps of infiltrative keratitis

A
  • Remove cause e.g. FB trapped under lens or use particular solution etc
  • Cease lens wear until infiltrate resolves
  • Prophylactic antibiotic may be required
  • Treat marginal lid disease if present e.g. blepharitis, before going back on lenses
  • Monitor progress, review px, complete resolution may require > 2 weeks
  • When resuming wear change to DW and high Dk lens
  • Re-educate patient about lens cleaning
42
Q

from starting management, after how long can infiltrative keratitis take to resolve

A

> 2 weeks

43
Q

why will you want to book a patient with infiltrative keratitis for a review

A

to see if its gotten worse or better and to avoid worse things like microbial keratitis

44
Q

what is a contact lens associated red eye CLARE

A

Inflammatory reaction of the cornea and conjunctiva immediately following a period of eye closure with CL wear due to endotoxins from gram negative bacteria

45
Q

which types of patients tend to suffer from CLARE and why

A
  • patients who nap/sleep in their contact lenses
    who will wake up with a painful red eye
    as there’s a lack of flushing of toxins due to reduced blink
  • also associated with tight fitting lenses
46
Q

which type of lens wearers tend to suffer from CLARE

A

EW lens wearers

47
Q

what causes the signs and symptoms of CLARE

A

hypersensitivity to toxins produced by gram negative bacteria

48
Q

what are the 3 signs of a contact lens associated red eye CLARE

A
  • Acute, unilateral, bulbar circumferential conjunctival hyperaemia
  • Cornea may be clear or there may be small midperipheral infiltrates present
  • A mild anterior chamber reaction-if severe
49
Q

what is a good indicator of a CLARE

A

when a px has woken up in the middle of the night with a painful red eye

50
Q

what are the 5 symptoms of a contact lens associated red eye CLARE

A
  • Woken up in mid of night with painful red eye
  • Redness
  • Lacrimation
  • Photophobia
  • FB sensation
51
Q

what are the 8 management steps of a contact lens associated red eye CLARE

A
  • Remove lens
  • Monitor-12-24 hrs to ensure diagnosis correct and not progressing to something else
  • Ocular lubricants
  • If severe may need prophylactic antibiotic
  • Resume wear when infiltrates resolved and no other signs and symptoms remain
  • Lid hygiene to reduce reoccurrence
  • Patient re-education
  • Refit with looser fitting lens and switch to DW
52
Q

what is the prognosis of a contact lens associated red eye

A

good

as it is a self limiting condition

53
Q

when will you resume contact lens wear after suffering from a contact lens associated red eye CLARE

A

when infiltrates are resolved and no other signs and symptoms remain

54
Q

what is a contact lens peripheral ulcer

A

Inflammatory reaction with focal excavation of the epithelium, infiltration and necrosis of the anterior stroma (Bowman’s layer intact)

55
Q

a contact lens peripheral ulcer is ________, but has an ________

A

a contact lens peripheral ulcer is sterile, but has an ulcer

56
Q

which type of patients is a contact lens peripheral ulcer incidence more greater in

A

EW wearers and seen less frequently in DW

57
Q

a contact lens peripheral ulcer is a _______________ ___________, not ____________

A

a contact lens peripheral ulcer is a inflammatory response, not infective

58
Q

which microorganism is a contact lens peripheral ulcer related to but what does not occur with this microorganism

A

related to bacteria, but bacteria do not invade or replicate in the cornea

59
Q

list 7 possible causes of a contact lens peripheral ulcer

A
  • bacterial contamination
  • hypoxia
  • closed eye
  • tight lens
  • poor hygiene
  • lid margin disease
  • smoking (don’t fit with overnight cl’s)
60
Q

what 2 other terms can a contact lens peripheral ulcer also be referred to as

A
  • sterile ulcer
    or
  • culture negative ulcer
61
Q

what are the 7 signs of a contact lens peripheral ulcer

A
  • Usually a single, unilateral, small round, sterile infiltrate, in peripheral cornea (less than 1mm)
  • overlying epithelium may stain
  • clearly defined margins of ulcer
  • mild conjunctival hyperaemia (usually sectoral)
  • limbal hyperaemia
  • may be a mid AC reaction if severe
  • no lid oedema
62
Q

which condition has a sectorial conjunctival hyperaemia

A

contact lens peripheral ulcer

63
Q

approx. _____ of patients with a contact lens peripheral ulcer will be _____________

A

approx. 50% of patients with a contact lens peripheral ulcer will be asymptomatic

64
Q

what are the 4 symptoms of a contact lens peripheral ulcer and what improves these symptoms

A
  • Px may experience mild FB sensation
  • Mild photophobia
  • Mild increase in lacrimation
  • lens intolerance
  • lens removal improves these symptoms
65
Q

what are the 6 management steps/options for a patient with a contact lens peripheral ulcer

A
  • Cease lens wear (~14 days, until epithelium heals)
  • Self-limiting, however, requires monitoring in case it’s MK (esp. first 24-48hrs) so call px back in next day to review
  • Ocular lubricants-dilutes toxins
  • If severe, prophylactic antibiotics
  • Eliminate source of bacteria e.g. CL case, CL, review care regime and hygiene
  • If recurrent refit with RGPs or dailies (which lowers the rate of infections)
66
Q

___________ of a contact lens peripheral ulcer is ______ but can leave a ______

A

prognosis of a contact lens peripheral ulcer is good but can leave a scar

67
Q

what is microbial keratitis

A

Infection of the cornea characterized by excavation of the corneal epithelium, Bowman’s layer, and stroma with infiltration and necrosis of tissue

68
Q

which microbe is most cases of microbial keratitis caused by

A

bacteria

69
Q

which types of bacteria causes microbial keratitis

A
  • Pseudomonas sp. gram -ve
  • Staphylococcus sp, grame +ve
  • other gram -ve organisms
70
Q

what can microbial keratitis lead to

A

blindness

71
Q

what type of people is microbial keratitis more associated with

A

EW lens wearers

72
Q

other than bacteria, what are the three other causes of microbial keratitis

A
  • acanthamoeba
  • viral
  • fungal
73
Q

what are the 8 signs of microbial keratitis

A
  • Localised corneal excavation, penetrating into the stroma, with underlying infiltrate and oedema
  • Central or paracentral, large (>1mm), irregular appearance corneal ulcer
  • Unilateral
  • Severe hyperaemia
  • Lid oedema.
  • Mucopurulent/watery discharge,
  • Aqueous flare often present
  • Conjunctival hyperaemia
74
Q

what are the 7 symptoms of microbial keratitis

A
  • Pain, acute onset, rapid progression
  • Very red
  • Reduced vision
  • Epiphora and photophobia
  • Lens removal = no improvement
  • Discharge - mucopurulent
  • Lacrimation

not all signs will be present

75
Q

what are the 11 possible risk factors that can cause microbial keratitis

A
  • Extended wear - restrict flushing of tears
  • Hypoxia – microorganisms adhere more strongly to the cornea in a hypoxic environment
  • Smoking
  • Poor hygiene – lenses, cases, hands etc
  • Swimming in contact lenses
  • Ocular surface disease e.g. recurrent corneal defect or dry eyes
  • Trauma
  • Ocular surgery
  • Diabetics
  • Topical steroid use
  • Topical anaesthetics - cornea is compromised
76
Q

what are the 8 management stages/options for microbial/bacterial keratitis

A
  • Cease lens wear
  • Refer to A and E as a ocular emergency
  • Corneal scrapes/Take CL case to A&E too
  • Px will require daily follow up (and possibly kept overnight) until condition resolves
  • Topical antibiotics
  • Dual therapy-combination of 2 antibiotics to cover gram +ve and gram –ve pathogens
  • Restrict any further lens wear
  • No more EW, possibly DW
77
Q

why should a patient with microbial keratitis take their contact lens case to A&E with them

A

to be cultured in order to see if it is caused by bacteria therefore can treat with antibiotics and to make sure its not caused by anything else e.g. fungus where antibiotics wont work

78
Q

what organism is acanthamoeba keratitis caused by

A 
a protozoan organism 
which feeds primarily on other microbes 
cant exists in 2 forms: 
- trophazoite - destroyed by CL solutions 
- cystic form - is more resistant
79
Q

how long can the cystic form of the protozoa acanthamoeba be dormant for

A

> 20 years

80
Q

what 5 things can possibly cause acanthamoeba keratitis

A 
- poor contact lens hygiene 
and/or exposure to:
- tap water 
- unpreserved solutions 
- swimming pools 
- soil
81
Q

acanthamoeba keratitis is a ________ ___________ condition

A

acanthamoeba keratitis is a sight threatening condition

82
Q

what are the 4 main signs of acanthamoeba keratitis

A

most signs as same as bacterial keratitis plus:

  • Begins as a nonspecific keratitis with infiltrates along the corneal nerves in a radial pattern
  • Ring infiltrate typically appears later in the disease process
  • Associated findings include limbal and scleral inflammation, hypopyon, hyperaemia
83
Q

what is the classic sign of acanthamoeba keratitis

A

ring infiltrate also called stellate lesions

84
Q

what are the 6 symptoms of acanthamoeba keratitis

A
  • Red eye
  • Blurred vision
  • Photophobia
  • Lacrimation
  • FB sensation
  • Pain
85
Q

what are the 3 management steps/options for acanthamoeba keratitis

A
  • immediate referral to ophthalmologist
  • culture may be taken
  • treated with broad spectrum antibiotics e.g. broline
86
Q

what other condition can acanthamoeba keratitis be mistaken for

A

viral infection

87
Q

what are the commonest pathogens of fungal keratitis

A
  • candida sp
    or
  • fusarium sp
88
Q

which 2 types of patients is fungal keratitis more likely to occur in

A
  • with a disorder of the immune system
    or
  • living in a warmer climate
89
Q

what is a fungal keratitis associated with

A

trauma with vegetative material and soils

90
Q

which other keratitis is the onest of fungal keratitis more slower than

A

slower than bacterial keratitis

91
Q

what can fungal keratitis be misdiagnosed as and what implications does this have

A
  • as bacterial keratitis
  • leads to delay in treatment as giving antibiotics instead of anti fungals

px will have a culture taken at hospital to avoid this

92
Q

what are the 5 signs of fungal keratitis

A
  • unilateral
  • hyperaemia
  • lacrimation
  • hypopyon
  • lid oedema
93
Q

what are the 3 symptoms of fungal keratitis

A
  • pain
  • photophobia
  • FB sensation
94
Q

what are the 4 possible management steps/options for a fungal keratitis and what may a fungal keratitis result in

A
  • Cease lens wear
  • Referral
  • Topical antifungals-some medications may only be available from specialist centres such as Moorfields
  • Deeper infections may require systemic antifungals
  • may result in corneal graft as it can lead to corneal perforation
95
Q

what way can a fungal keratitis be differentiated from a bacterial keratitis

A

by taking a good history

as fungal is slower to progress

96
Q

what does each letter of the acronym PEDAL stand for and explain what each ones means

A
  • Pain:
    can vary, but generally worse with infections
  • Epithelial defect:
    more likely to be an infecting microbe, but could be caused by actions of the white blood cells aswell
  • Discharge:
    variable, but mucopurolent discharge is associated with infection
  • Anterior chamber:
    almost always present during active ulceration, but could vary from dense flare to trace cells. some sterile lesions may also be associated with a mild AC reaction
  • Location:
    ulcers tendency to favour central cornea i.e further from limbal vasculature

Contact lenses year 3 (15 decks)

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