infective and non infective keratitis Flashcards
what is a infective keratitis also referred to as
microbial
what is a non infective keratitis also referred to as
sterile
what are corneal infiltrates
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
what is the appearance of corneal infiltrates
a white/grey appearance which does NOT break through the corneal epithelium
what will not happen as a result of infiltrates not breaking through the corneal epithelium
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
what are not all corneal infiltrative events CIE
not all are microbial keratitis
what are all microbial keratitis cases called
cornel infiltrative events
any keratitis is called a corneal infiltrative event
what can some corneal infiltrates turn into
defects which have turned into ulcers
what is a corneal ulcer
an epithelial defect with underlying inflammation
what will be the ddx check between corneal infiltrates and corneal ulcers
a fluorescein stain check
where will corneal infiltrates form and why
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
what can sterile non-infective inflammation of the cornea not be attributed to
to one specific cause
it has many different triggers
list 4 possible triggers of a sterile non-infective inflammation of the cornea and what increases the likelihood of all these triggers
- trauma
- toxicity
- immune response
- hypersensitivity
contact lens wear increases likelihood of all these triggers
what happens to the corneal cells which causes sterile non-infective inflammation of the cornea
they become distressed, release chemical agents which lead to inflammatory response
explain how trauma is a trigger which can cause sterile non-infective inflammation of the cornea
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
explain how solution toxicity is a trigger which can cause sterile non-infective inflammation of the cornea
especially from contact lens solution containing thimerosal or chlorhexidine
explain how lens deposits is a trigger which can cause sterile non-infective inflammation of the cornea
from Proteins, lipids etc.
Epithelial distress may also be induced from dead epithelial cells and debris trapped under immobile EW lens
list 5 causes of a infective ulcer
- bacteria
- fungus
- virus
- parasite
- autoimmunity
how fast can an infective ulcer progress and what implication does this have
as fast as 12-24 hours
can cause visual loss
must refer immediately to an ophthalmologist
what damage can a infective ulcer in the case of microbial involvement cause to the ocular structure
excavation of the corneal stroma which can lead to an anterior chamber response of flare
what are the 3 various classification systems proposed on the ddx/diagnosis of a corneal ulcer
- ulcerative vs non ulcerative
- suppurative vs nonsuppurative (whether it produces discharge/pus or not)
- central vs peripheral keratitis
list 3 reasons why the classification system of ulcerative vs non ulcerative is not a good indicator of an infective ulcer
- 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
why is the classification system of suppurative vs nonsuppurative not a good indicator of an infective ulcer
because there are reports where microbial keratitis has been diagnosed without any discharge
why is the classification system of central vs peripheral keratitis not a good indicator of an infective ulcer
it is not a good indicator as to whether the infiltrate is sterile or not
what are asymptomatic infiltrates
infiltrates in patients without any further signs or symptoms
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
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
what are the symptoms of asymptomatic infiltrates
none
hence asymptomatic
what other condition can asymptomatic infiltrates be a mild form of
CLARE
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
what is a more serious version of asymptomatic infiltrates
asymptomatic infiltrative keratitis
what is asymptomatic infiltrative keratitis
an inflammatory event characterized by infiltration of the cornea without patient symptoms
has a similar presentation to asymptomatic infiltrates
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
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)
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
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
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
what are the 4 symptoms of infiltrative keratitis
- Discomfort, FB sensation, irritation
- Hyperaemia
- Possible mild photophobia
- lacrimation
when may a patient be asymptomatic in infiltrative keratitis
when the infiltrates are minor
when do symptoms of infiltrative keratitis reduce
on lens removal
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
from starting management, after how long can infiltrative keratitis take to resolve
> 2 weeks
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
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
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
which type of lens wearers tend to suffer from CLARE
EW lens wearers
what causes the signs and symptoms of CLARE
hypersensitivity to toxins produced by gram negative bacteria
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
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
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
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
what is the prognosis of a contact lens associated red eye
good
as it is a self limiting condition
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
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)
a contact lens peripheral ulcer is ________, but has an ________
a contact lens peripheral ulcer is sterile, but has an ulcer
which type of patients is a contact lens peripheral ulcer incidence more greater in
EW wearers and seen less frequently in DW
a contact lens peripheral ulcer is a _______________ ___________, not ____________
a contact lens peripheral ulcer is a inflammatory response, not infective
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
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)
what 2 other terms can a contact lens peripheral ulcer also be referred to as
- sterile ulcer
or - culture negative ulcer
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
which condition has a sectorial conjunctival hyperaemia
contact lens peripheral ulcer
approx. _____ of patients with a contact lens peripheral ulcer will be _____________
approx. 50% of patients with a contact lens peripheral ulcer will be asymptomatic
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
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)
___________ 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
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
which microbe is most cases of microbial keratitis caused by
bacteria
which types of bacteria causes microbial keratitis
- Pseudomonas sp. gram -ve
- Staphylococcus sp, grame +ve
- other gram -ve organisms
what can microbial keratitis lead to
blindness
what type of people is microbial keratitis more associated with
EW lens wearers
other than bacteria, what are the three other causes of microbial keratitis
- acanthamoeba
- viral
- fungal
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
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
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
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
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
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
how long can the cystic form of the protozoa acanthamoeba be dormant for
> 20 years
what 5 things can possibly cause acanthamoeba keratitis
- poor contact lens hygiene and/or exposure to: - tap water - unpreserved solutions - swimming pools - soil
acanthamoeba keratitis is a ________ ___________ condition
acanthamoeba keratitis is a sight threatening condition
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
what is the classic sign of acanthamoeba keratitis
ring infiltrate also called stellate lesions
what are the 6 symptoms of acanthamoeba keratitis
- Red eye
- Blurred vision
- Photophobia
- Lacrimation
- FB sensation
- Pain
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
what other condition can acanthamoeba keratitis be mistaken for
viral infection
what are the commonest pathogens of fungal keratitis
- candida sp
or - fusarium sp
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
what is a fungal keratitis associated with
trauma with vegetative material and soils
which other keratitis is the onest of fungal keratitis more slower than
slower than bacterial keratitis
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
what are the 5 signs of fungal keratitis
- unilateral
- hyperaemia
- lacrimation
- hypopyon
- lid oedema
what are the 3 symptoms of fungal keratitis
- pain
- photophobia
- FB sensation
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
what way can a fungal keratitis be differentiated from a bacterial keratitis
by taking a good history
as fungal is slower to progress
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
