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

infective and non infective keratitis Flashcards

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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
what are asymptomatic infiltrates
infiltrates in patients without any further signs or symptoms
26
who may asymptomatic infiltrates be present in and what can be the cause
- 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
27
what are the 4 signs of asymptomatic infiltrates
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
28
what are the symptoms of asymptomatic infiltrates
none | hence asymptomatic
29
what other condition can asymptomatic infiltrates be a mild form of
CLARE
30
what are the 2 management steps of asymptomatic infiltrates
- Px lens care regime and compliances should be checked | - Perhaps review, but may texts recommend no further management required
31
what is a more serious version of asymptomatic infiltrates
asymptomatic infiltrative keratitis
32
what is asymptomatic infiltrative keratitis
an inflammatory event characterized by infiltration of the cornea without patient symptoms has a similar presentation to asymptomatic infiltrates
33
what are the 5 signs of asymptomatic infiltrative keratitis
- 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
34
what are the 4 management steps of asymptomatic infiltrative keratitis
- Cease CL wear - Review px - Prophylactic antibiotic possibly required - Advise against EW (to avoid a hypoxic environment for the cornea)
35
what is infiltrative keratitis
An inflammatory reaction of the cornea characterized by anterior stromal infiltration, with or without epithelial involvement, in the midperiphery to periphery of the cornea
36
what are the 4 signs of infiltrative keratitis
- 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
37
which condition is the signs of infiltrative keratitis similar to and therefore what will you have to go by to ddx
asymptomatic infiltrative keratitis, so have to go by the patients symptoms
38
what are the 4 symptoms of infiltrative keratitis
- Discomfort, FB sensation, irritation - Hyperaemia - Possible mild photophobia - lacrimation
39
when may a patient be asymptomatic in infiltrative keratitis
when the infiltrates are minor
40
when do symptoms of infiltrative keratitis reduce
on lens removal
41
what are the 7 management steps of infiltrative keratitis
- 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
from starting management, after how long can infiltrative keratitis take to resolve
> 2 weeks
43
why will you want to book a patient with infiltrative keratitis for a review
to see if its gotten worse or better and to avoid worse things like microbial keratitis
44
what is a contact lens associated red eye CLARE
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
which types of patients tend to suffer from CLARE and why
- 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
which type of lens wearers tend to suffer from CLARE
EW lens wearers
47
what causes the signs and symptoms of CLARE
hypersensitivity to toxins produced by gram negative bacteria
48
what are the 3 signs of a contact lens associated red eye CLARE
- 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
what is a good indicator of a CLARE
when a px has woken up in the middle of the night with a painful red eye
50
what are the 5 symptoms of a contact lens associated red eye CLARE
- Woken up in mid of night with painful red eye - Redness - Lacrimation - Photophobia - FB sensation
51
what are the 8 management steps of a contact lens associated red eye CLARE
- 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
what is the prognosis of a contact lens associated red eye
good | as it is a self limiting condition
53
when will you resume contact lens wear after suffering from a contact lens associated red eye CLARE
when infiltrates are resolved and no other signs and symptoms remain
54
what is a contact lens peripheral ulcer
Inflammatory reaction with focal excavation of the epithelium, infiltration and necrosis of the anterior stroma (Bowman’s layer intact)
55
a contact lens peripheral ulcer is ________, but has an ________
a contact lens peripheral ulcer is sterile, but has an ulcer
56
which type of patients is a contact lens peripheral ulcer incidence more greater in
EW wearers and seen less frequently in DW
57
a contact lens peripheral ulcer is a _______________ ___________, not ____________
a contact lens peripheral ulcer is a inflammatory response, not infective
58
which microorganism is a contact lens peripheral ulcer related to but what does not occur with this microorganism
related to bacteria, but bacteria do not invade or replicate in the cornea
59
list 7 possible causes of a contact lens peripheral ulcer
- bacterial contamination - hypoxia - closed eye - tight lens - poor hygiene - lid margin disease - smoking (don't fit with overnight cl's)
60
what 2 other terms can a contact lens peripheral ulcer also be referred to as
- sterile ulcer or - culture negative ulcer
61
what are the 7 signs of a contact lens peripheral ulcer
- 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
which condition has a sectorial conjunctival hyperaemia
contact lens peripheral ulcer
63
approx. _____ of patients with a contact lens peripheral ulcer will be _____________
approx. 50% of patients with a contact lens peripheral ulcer will be asymptomatic
64
what are the 4 symptoms of a contact lens peripheral ulcer and what improves these symptoms
- Px may experience mild FB sensation - Mild photophobia - Mild increase in lacrimation - lens intolerance - lens removal improves these symptoms
65
what are the 6 management steps/options for a patient with a contact lens peripheral ulcer
- 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
___________ of a contact lens peripheral ulcer is ______ but can leave a ______
prognosis of a contact lens peripheral ulcer is good but can leave a scar
67
what is microbial keratitis
Infection of the cornea characterized by excavation of the corneal epithelium, Bowman’s layer, and stroma with infiltration and necrosis of tissue
68
which microbe is most cases of microbial keratitis caused by
bacteria
69
which types of bacteria causes microbial keratitis
- Pseudomonas sp. gram -ve - Staphylococcus sp, grame +ve - other gram -ve organisms
70
what can microbial keratitis lead to
blindness
71
what type of people is microbial keratitis more associated with
EW lens wearers
72
other than bacteria, what are the three other causes of microbial keratitis
- acanthamoeba - viral - fungal
73
what are the 8 signs of microbial keratitis
- 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
what are the 7 symptoms of microbial keratitis
- 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
what are the 11 possible risk factors that can cause microbial keratitis
- 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
what are the 8 management stages/options for microbial/bacterial keratitis
- 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
why should a patient with microbial keratitis take their contact lens case to A&E with them
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
what organism is acanthamoeba keratitis caused by
``` 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
how long can the cystic form of the protozoa acanthamoeba be dormant for
> 20 years
80
what 5 things can possibly cause acanthamoeba keratitis
``` - poor contact lens hygiene and/or exposure to: - tap water - unpreserved solutions - swimming pools - soil ```
81
acanthamoeba keratitis is a ________ ___________ condition
acanthamoeba keratitis is a sight threatening condition
82
what are the 4 main signs of acanthamoeba keratitis
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
what is the classic sign of acanthamoeba keratitis
ring infiltrate also called stellate lesions
84
what are the 6 symptoms of acanthamoeba keratitis
- Red eye - Blurred vision - Photophobia - Lacrimation - FB sensation - Pain
85
what are the 3 management steps/options for acanthamoeba keratitis
- immediate referral to ophthalmologist - culture may be taken - treated with broad spectrum antibiotics e.g. broline
86
what other condition can acanthamoeba keratitis be mistaken for
viral infection
87
what are the commonest pathogens of fungal keratitis
- candida sp or - fusarium sp
88
which 2 types of patients is fungal keratitis more likely to occur in
- with a disorder of the immune system or - living in a warmer climate
89
what is a fungal keratitis associated with
trauma with vegetative material and soils
90
which other keratitis is the onest of fungal keratitis more slower than
slower than bacterial keratitis
91
what can fungal keratitis be misdiagnosed as and what implications does this have
- 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
what are the 5 signs of fungal keratitis
- unilateral - hyperaemia - lacrimation - hypopyon - lid oedema
93
what are the 3 symptoms of fungal keratitis
- pain - photophobia - FB sensation
94
what are the 4 possible management steps/options for a fungal keratitis and what may a fungal keratitis result in
- 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
what way can a fungal keratitis be differentiated from a bacterial keratitis
by taking a good history | as fungal is slower to progress
96
what does each letter of the acronym PEDAL stand for and explain what each ones means
- 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

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