Infectious Corneal Disorders Flashcards
what G+ bacteria are implicated in infectious keratitis
staph aureus & strep pyogenes
what G- bacteria are implicated in infectious keratitis
pseudomonas aeruginosa & neiserria gonorrhea
what does staph require to cause an infectious keratitis
significant corneal epithelium compromise
how does neiserria gonorrhea cause an infectious keratitis
it can penetrate intact corneal epithelium
what viruses are implicated in infectious keratitis
herpes simplex & herpes zoster
what fungi are implicated in infectious keratitis
aspergillus, fusarium & candida
what parasites are implicated in infectious keratitis
acanthamoeba
when pain = presentation of infectious keratitis, what organism causes the infection
bacterial & viral
when pain < presentation of infectious keratitis, what organism causes the infection
fungal
when pain»_space; initial presentation of infectious keratitis, what organism causes the infection
acanthamoeba
what are the common signs of infectious keratitis
- conjunctival hyperemia
- anterior chamber inflammation
- large epithelial ulceration overlying corneal infiltrate
what is the major risk factor for infectious keratitis & why
CL wear
- corneal epithelial hypoxia
- bacterial adherence to lens surface
what are other risk factors for developing an infectious keratitis
- trauma
- ocular surface diseases
- immunosuppression (HIV/AIDS, diabetes)
corneal infiltrates are
leukocyte infiltration into corneal stroma
is a hypersensitivity reaction to an antigen an infectious or non-infectious corneal infiltrate
non-infectious
when the immune system is directly battling an infectious organism, is that a infectious or non-infectious corneal infiltrate
infectious
corneal infiltrates: infectious or non-infectious
- larger & solitary
infectious
corneal infiltrates: infectious vs. non-infectious
- peripheral/scattered
non-infectious
corneal infiltrates: infectious vs. non-infectious
- overlying epithelial defect stains well w/ NaFl
infectious
corneal infiltrates: infectious vs. non-infectious
- anterior chamber inflammation
infectious
corneal infiltrates: infectious vs. non-infectious
- commonly unilateral
infectious
corneal infiltrates: infectious vs. non-infectious
- milder level of discomfort
non-infectious
corneal infiltrates: infectious vs. non-infectious
- injected “angry” eye
infectious
when should a corneal culture be performed
- when ulcer does not respond to aggressive therapy
- a large, central ulcer is present
- case history & clinical presentation point away from the common organisms
blood agar is a routinely used media for what
most bacteria & fungi
chocolate agar is a routinely used media for what
N. gonorrhea
sabouraud is a routinely used media for what
fungi
MacConkey agar is a routinely used media for what
G- bacteria
MacConkey agar is optimal for what organism
pseudomonas
clinical findings:
- circumlimbal injection
- stromal edema
- folds in Descemet’s membrane
- anterior chamber reaction: WBCs
- conjunctival & eyelid chemosis
bacterial keratitis
what are the late complications in bacterial keratitis
scarring & perforation
what type of topical antibiotic is used to treat bacterial keratitis
broad spectrum (G+ & G-)
why is a topical cycloplegic used to manage bacterial keratitis & which cycloplegic drops are used, how frequently & which one is more preferable
- cyclopentolate 1%
- homatropine 5% → preferable bc it lasts longer
- BID-TID
in bacterial keratitis, when can steroids be used as treatment
when the epithelial defect is healed
how often should you see a patient with bacterial keratitis
daily until significant improvement
what is a small, non-central ulcer & infiltrate < 1.5mm
microbial keratitis
how do you treat a microbial keratitis
must be broad spectrum → 4th gen fluoroquinolones
what microbial keratitis ulcers are central, with an infiltrate > 2mm & unresponsive to initial treatment
high-risk ulcers
when treating a microbial keratitis high-risk ulcer, what is the loading dose in office
5 qtt of 4th gen fluoroquinolone separated by 5 min each
what kind of antibiotics would you use for a high-risk microbial keratitis ulcer
fortified antibiotics → cephalosporins (G+) & aminoglycosides (G-)
- cefalozin/cefuroxime/ceftazidime 50mg/mL q1h with vancomycin 50mg/ml or tobramycin 15 mg/ml qih
how would you apply the fortified antibiotics
alternate 1 qtt every 30 min in the affected eye
what infectious corneal disorder has:
- insidious onset & growth
- elicits significant inflammatory response w/ hypopyon
- ocular signs are typically worse than symptoms
- can lead to corneal perforation
fungal keratitis
what is a type of fungal yeast & how does it reproduce
candida → reproduce by budding
what are some types filamentous fungi & how does it reproduce
aspergillus & fusarium → grow by producing hyphae
- chronic ocular surface disease
- long-term use of topical steroids
- CL wear
- systemic immunosuppression
- diabetes
- injury with vegetable matter
these are all?
predisposing factors for fungal keratitis
which type of fungi is more common in fungal keratitis
filamentous
fungal keratitis with a dense yellow-white infiltrate is from which type of fungi
candida
fungal keratitis with:
- yellow-white/grey infiltrate with fluffy margins
- satellite lesions
- feathery branch-like lesions
- large infiltrates with possible small epithelial defect
- anterior uveitis with hypopyon
- can have bacterial hyperinfection
is from which type of fungi
filamentous
when should you culture for a fungal keratitis
prior to starting treatment
what media would you use for fungal keratitis
sabouraud/chocolate agar (allows labs to test for sensitivity of antifungal agents) → PCR
when should you perform a corneal biopsy for a fungal keratitis
if no improvement in 3-4 days of treatment
if no organisms grow on culture
what do you use to treat fungal keratitis until lab results arrive
antibiotic cover
what is the treatment regimen for topical antifungals & give some examples
q1h for 48hr → taper slowly when it improves
treatment required for 4-6 weeks
medications: natamycin 5%, amphotericin B
what do you use to reduce corneal thinning when treating fungal keratitis
doxycycline 100mg BID PO
can you use steroids to treat fungal keratitis
no
what infectious disorder is frequently misdiagnosed as herpes simplex keratitis in its early stages
acanthamoeba keratitis
who have an increased risk of acanthamoeba keratitis
CL wearers who:
- swim in CLs
- use tap water to clean CLs or CL cases
- poor hygiene
signs:
- early → epithelial surface is irregular & gray
- formation of epithelial pseudodendrites
- limibitis with diffuse or focal stromal infiltrates
- stromal infiltrates enlarge & coalesce to form a ring
acanthamoeba keratitis
what is a pathognomonic sign of acanthamoeba keratitis
perineural infiltrates (keratoneuritis)
sequelae:
- scleritis
- slowly progressing stromal opacification & vascularization
- corneal opacification & melting
these are all sequelae of what infectious disorder
acanthamoeba keratitis
how would you investigate to determine if it is acanthamoeba keratitis
culture, PCR, corneal biopsy
what media would you use to culture acanthamoeba keratitis
non-nutrient agar w/ dead E. coli
what is the treatment regimen for acanthamoeba keratitis
anti-protozoa treatment q1h & reduced when it improves
- polyhexamethylene biguianide 0.02%
- chlorhexidine 0.02% q1h
- brolene q1h
these are all what kind of treatment
anti-protozoa treatments
many cases of acanthamoeba keratitis require?
corneal transplant
when would you use an antibiotic to treat acanthamoeba keratitis
when there is a bacterial superinfection
how do you manage the pain that comes with acanthamoeba keratitis
oral NSAID & cycloplegia
can you use steroids to treat acanthamoeba keratitis?
no
an enveloped double-stranded DNA virus
herpes simplex virus (HSV)
which type of HSV is above the waist (facial, oral, labial)
type 1
which type of HSV is a genital infection & is rarely transmitted to eye
type 2
when does primary infection of HSV occur & how
in childhood via droplet transmission
which HSV infection may develop dermatitis & conjunctivitis
primary infection
what can induce HSV reactivation & prolferation
stressors like fever, hormonal changes, UV radiation, trauma, psychological stress
in a recurrent infection of HSV, the pattern of disease depends on
site of reactivation
what are the risk factors for severe disease in recurrent HSV infection
atopy
immunodeficiency
immunosuppression
topical steroids
these ocular manifestations are from what infectious disorder?
- dermatitis
- keratitis
- blepharitis
- conjunctivitis
- uveitis
- retinitis
HSV
in HSV, what are the more common forms of keratitis
- epithelial (80%)
- stromal (15%)
what ocular manifestation in HSV causes elevated IOP
trabeculitis
what ocular manifestations occur in the epithelium with a live HSV virus
- dendritic ulcer
- geographic ulcer
what ocular manifestations occur in the stroma with a live HSV virus
necrotizing keratitis
what ocular manifestations occur in the anterior chamber with a live HSV virus
keratouveitis
an immune reaction of the HSV virus in the stroma causes
immune keratitis
an immune reaction of the HSV virus in the endothelium causes
disciform keratitis
an immune reaction of the HSV virus in the anterior chamber causes
keratouveitis
this presentation is indicative of what infectious disorder?
- clear vesicles on erythematous skin base
- crust & self-heal
- may cause follicular conjunctivitis
HSV dermatitis
what is the management for HSV dermatitis
- warm/cool soaks
- antibiotic treatment
- topical antiviral
in HSV dermatitis, when would you use a topical antiviral
if eyelid margin is involved
this presentation is indicative of what infectious disorder?
- bulbar conjunctival injection & chemosis
- palpebral conjunctival follicles
- palpable preauricular node
HSV conjunctivitis
how do you manage HSV conjunctivitis
- topical antivirals
- artificial tears
mild anterior uveitis (grade 1 cells in AC) is present in which ocular manifestation of HSV
HSV epithelial keratitis
a classic dendritic ulcer is indicative of which ocular manifestation of HSV
HSV epithelial keratitis
in a dendritic ulcer, NaFl stains ______ & Rose Bengal stains ______
NaFl → body of ulcer
Rose Bengal → terminal bulbs
which infectious corneal disorder is the most common corneal infection in the US
HSV epithelial keratitis
which HSV ocular manifestation is caused by reactivation of the virus after a primary oral-labial infection
HSV epithelial keratitis
when performing a clinical exam for HSV epithelial keratitis, what are you testing for
symmetry/asymmetry between the eyes
in HSV epithelial keratitis, when do you test for corneal sensitivity
before instillation of drops
in HSV epithelial keratitis, why do you check IOP
to check for trabeculitis
which topical medication do you use to treat HSV epithelial keratitis & what are the 2 drugs
steroids → trifluridine (Viroptic) & ganciclovir gel (Zirgan)
what medication CANNOT be used for HSV epithelial keratitis
steroids
what oral medication do you use to treat HSV epithelial keratitis & what is the dosage
acyclovir (Zovirax) → 400mg 5x/day 7-10 days (therapeutic dose)
which HSV ocular manifestation causes the most severe morbidity
HSV immune stromal keratitis
when does HSV immune stromal keratitis occur & why
usually after a previous episode of HSV epithelial keratitis
antibody-complement cascade against retained viral antigens in the stroma
mid-deep stromal infiltrate w/ intact epithelium that leads to deep stromal vascularization & scarring is indicative of which HSV ocular manifestation
HSV immune stromal keratitis
which type of medications & which drug do you use to treat HSV immune stromal keratitis
topical steroid → prednisolone 1% 6-8x/day w/ long taper (at least 10 weeks)
oral prophylactic antiviral cover → acyclovir 400mg BID during steroid use
why do you have to add an oral antiviral cover when using a topical steroid for HSV immune stromal keratitis
if only given the steroid → epithelial dendrite can develop
which HSV ocular manifestation is a cell-mediated immune reaction to viral antigens
HSV endothelial/disciform keratitis
which HSV ocular manifestation results in acute onset of diffuse stromal edema
HSV endothelial/disciform keratitis
these symptoms are indicative of which HSV ocular manifestation:
- gradual onset of vision blur
- photophobia & halos around lights
HSV endothelial/disciform keratitis
these clinical findings are indicative of which HSV ocular manifestation:
- stromal & epithelial edema confined to central cornea
- large granulomatous KPs underlying edema
- folds in Descemet’s membrane
- elevated IOP
- reduced corneal sensation
HSV endothelial/disciform keratitis
how do you treat HSV endothelial/disciform keratitis
- topical steroid w/ slow taper
- antiviral cover: acyclovir 400mg 5x/day for 7-10 days → then prophylactic dose
which HSV ocular manifestation can occur in isolation or in association w/ HSV epithelial, stromal, or endothelial
HSV keratouveitis
these signs are indicative of which HSV ocular manifestation:
- acute trabeculitis → increased IOP
- anterior chamber reaction
- possible hypopyon
HSV keratouveitis
what is a possible sequelae of HSV keratouveitis
transillumination defect of the iris
how do you treat HSV keratouveitis
- topical steroid w/ slow taper
- prophylactic antiviral cover
which HSV ocular manifestation is the end result of repeat attacks of HSV keratitis causing damage to corneal nerves resulting in decreased corneal sensation
HSV neurotrophic keratitis
decreased corneal sensation in HSV neurotrophic keratitis results in what
decreased tear production & blink rate
where is HSV neurotrophic keratitis located & its appearance
ulcer is interpalpebral w/ smooth borders
how can you treat HSV neurotrophic keratitis
- aggressive lubrication
- tarsorrhaphy
- amniotic membrane
- Oxervate (recombinant human nerve growth factor)
HEDS I & II found that prophylactic dose of acyclovir does what
significantly reduces incidence of recurrent epithelial & stromal keratitis
HEDS recommendation is for which HSV ocular manifestation
- initial episode → no prophylactic therapy
- 1+ episode → treat active ulcer first → oral therapy for 1 yr
epithelial disease
HEDS recommendation is for which HSV ocular manifestation
- initial episode: oral therapy for 1 yr
- 1+ episodes: treat active ulcer first → oral therapy for at least 2 years
stomal disease
what is the primary & secondary infection of VZV
- primary → chickenpox (varicella)
- secondary → shingles (herpes zoster)
reactivation of herpes zoster is most commonly along which dermatomes
thoracic & lumbar
reactivation of herpes zoster in which dermatome is next most common & what is it called
trigeminal dermatome → herpes zoster ophthalmicus
acute shingles (herpes zoster) skin lesions manifest in what way
strictly respect midline
which branch of the trigeminal nerve dose reactivation of HZV affect more often & which branch of that is most commonly involved
V1 → frontal nerve
when nasociliary nerve is involved in reactivation of VZV, what is the sign called
Hutchinson’s sign
frontal nerve innervates which structures
forehead, upper eyelid
how can you distinguish Hutchinson’s sign
vesicular eruption on tip of nose
what ocular structures are involved in Hutchinson’s
sclera, cornea, iris, ciliary body, choroid
most is the most common ocular manifestation of HZO
epithelial keratitis
which ocular manifestation of HZO has pseudodentrite mucus plaques caused by swollen epithelial cells
HZO epithelial keratitis
how can you differentiate HZO epithelial keratitis vs HSV epithelial keratitis
HZO epithelial keratitis has no terminal bulbs
which HZO ocular manifestation is usually mild & responsive to topical steroid treatment
HZO stromal keratitis
what happens to the iris from HZO
iris atrophy
what is the treatment for herpes zoster
- oral antiviral within 72 hours of maculopapular rash onset → acyclovir 800mg PO 5x.day x 7-10 days
if the oral antiviral is taken within the 72 hours of the herpes zoster rash, what does it reduce the risk of
postherpetic neuralgia
what can you use to treat herpes zoster in its active phase if it is severe & what does it do
oral steroid → reduces scarring & pain
- prednisone 60mg PO x 4 days → taper
VZV Varivax is given to which age group & what does it do
given in childhood → prevents chickenpox & future shingles
VZV Zostavax is given to which age group and what does it do
pts 60+ years → 50% reduced risk of shingles for 5-8 years
VZV Shingrix is given to which age group and what does it do
pts 50+ years → prevents herpes zoster & postherpetic neuralgia
if HZV has a bilateral presentation, what should you consider
atopy (allergies), thymoma, immunocompromised
