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CORNEA ANOMALIES > INFECTIOUS CORNEAL DZ > Flashcards

INFECTIOUS CORNEAL DZ Flashcards

1
Q

Intact corneas can be invaded by what type of organisms?

A
  • Corynebacterium Diphtheria
  • Neisseria Gonorrhoeae
  • Neisseria Meningitidis
  • Haemophilus influenzae
  • Listeria

Pneumonic: Canadian National Hockey League (CNHL)

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2
Q

what is the most common bacterias to invade compromised corneas?

A
  • Pseudomonas aeruginosa (gram -) – 60% of CL related ulcers!
  • Staphylococcus aureus (gram +)
  • Streptococci (gram +)
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3
Q

what is bacterial keratitis?

A
  • It is a serious, sight-threatening bacterial infection that tends to develop in pts with intact or compromised corneal surface
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4
Q

what are the most likely bacteria to be involved compromised cornea?

A
  1. staph aureus (+)
  2. staph epidermidis (+)
  3. strep pneumoniae (+)
  4. pseudomonas aeruginosa (-)
  5. haemophilus influenzae
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5
Q

general symptoms of all infectious keratitis?

A

3 P’s:
* pain
* photophobia
* purulent discharge

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6
Q

signs for a bacterial keratitis?

A
  • Well-defined corneal opacity which may be either to an infiltrate or an ulcer.
  • Corneal edema
  • Severe conjunctival injection
  • Chemosis and eyelid edema
  • AC cells & flare –> may develop a hypopyon.
  • Perforation –> depending if not tx.
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7
Q

w/u for bacterial keratitis?

A
  • Gram stain (smear) – test for bacteria
  • Chocolate agar plate – test for Haemophilus & Neisseria
  • Thioglycolate culture broth / or blood agar plate – test for aerobic & anerobic bacteria
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8
Q

tx for bacterial keratitis?

A

always tx ulcers & infiltrate as bacterial unless there is high suspicioun of a different etiology.
* topical ABx – Ciprofloxacin, ofloxacin, Levofloxacin are FDA approved for this - 2 gtts every 15min x 6hrs –> then 2 gtts every 30min for 18hrs –> then taper.
* topical cycloplegic– comfort & to prevent formation of synechiae.
* topical steroid – once infx is under control to reduce inflammation & scarring.
* F/U next day –> then 3 days –> then 5 days.

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9
Q

what is fungal keratitis?

A

fungal infection that causes keratitis.

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10
Q

how does someone get fungal keratitis?

A
  • trauma involving vegatative matter (plant/tree/fingernails)
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11
Q

what are the 3 offending fungal agents in fungal keratitis?

A
  1. Candida (yeast) – often occur in eyes with chronic corneal disease (chronic dry eye, HSV, exposure keratopathy) or in immunocompromised pts.
  2. Aspergillus (filamentous)
  3. Fusarium (filamentous)

Aspergillus & Fusarium are common after vegetative matter.

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12
Q

w/u for fungal keratitis?

A
  • Sabouraud’s agar – test for fungi
  • KOH / or Giemsa stain – test for fungi/yeast
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13
Q

tx for fungal keratitis?

A

Topical or systemic antifungal
* Topical Natamycin (gtts) – 1st line
* Fluconazole (po)
* Voriconazole (po)

Topical cycloplegic:
* for comfort.

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14
Q

what is acanthamoeba keratitis? how does someone get it?

A

Rare, parasitic infection associated w/ inadequate contact lens hygiene (tap water use, swimming in CL at lakes or pools).

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15
Q

what is the offending agent in acanthamoeba keratitis?

A

acanthamoeba

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16
Q

where is acanthamoeba found?

A

soil, water, oral cavity of humans

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17
Q

additional symptoms of acanthamoeba keratitis?

A
  • pain will be far more severe than signs.
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18
Q

signs for acanthamoeba keratitis?

A

Early
* Small punctate or pseudo-dendritic epithelial defects (may confuse w/ HSV) – pain that does not match defect.

Late:
* Radial Keratoneuritis (inflammation of corneal nerves)
* Patchy anterior stomal infiltrates - gradually progress to ring-like stromal infiltrate.

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19
Q

w/u for acanthamoeba keratitis?

A
  • Culture (gold standard) – Non-nutrient agar plate with heat-killed E.coli.
  • Confocal microscopy –Appear as hyperreflective spherical cysts.
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20
Q

tx for acanthamoeba keratitis?

A
  • hospitalized initially
  • First line therapy – Chlorhexidine combined with Brolene 0.02% q1h x 2-3 days around the
    clock then q1h while awake x 3 days then tapered to QID.
  • Second line therapy – PHMD 0.02% q1h x 2-3 days around the clock then q1h while awake x 3 days, then tapered to QID.
  • topical cycloplegic & oral NSAID may be used for pain.
  • f/u every 1-4 days then every 1-3 wks.

*** tx last 3-12 months!

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21
Q

what is herpes simplex keratitis? how is someone affected with it?

A
  • infectious keratitis caused by DNA virus HSV1
  • Virus transferred by direct contact w/ cold sores, saliva or fomites.
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22
Q

where does the HSV1 virus lay dormant?

A
  • trigeminal ganglion
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23
Q

what is recurrent HSV?

A

it is reactivation of the latent infection in the trigeminal ganglion.

24
Q

what causes reactivation of HSV?

A

Reactivation causes:
* physical or emotional stress.
* sun exposure
* fever
* immune system response to HSV.

25
Q

what are symptoms of HSV1 keratitis?

A
  • pain
  • serous discharge
  • photophobia
26
Q

General signs (not based on classification type) of HSV1 keratitis?

A
  • pustules on eyelids
  • AC cells & flare
  • KPs
  • other signs are classified based on which layer it is found in the cornea.
27
Q

what are the 4 classification of recurrent HSV?

A
  1. epithelial keratitis
  2. stromal keratitis
  3. disciform keratitis
  4. neurotrophic keratitis
28
Q

what is HSV - epithelial keratitis?

A

direct invasion of corneal epithelial cells by HSV.

29
Q

signs of HSV - epithelial keratitis?

A
  • Dendritic ulcers – appear as linear branching with terminal bulbs. –> early in dz course dendrite may appear as PEE.
  • Geographic ulcers – like dendritic ulcer but wider (no longer linear) in appearance  associated with previous topical steroid use!
30
Q

The edges of an HSV dendrite contain ____ ____ ____.

A

active viral cells

31
Q

Edges of HSV dendritic ulcer will stain with ___ ___ and the center of the ulcer will stain with ___ ___.

A

rose bengal, sodium Fluorescein

32
Q

what is HSV - Stromal keratitis?

A

It is an inflammatory response to viral replication w/in the stroma

33
Q

signs of HSV - stromal keratitis?

A

Can present in 2 ways:
* Interstitial keratitis (IK) – characterized by an infiltrate with diffused neovascularization but no epithelial defect.
* Necrotizing keratitis – stromal infiltrate with overlying epithelial defect (ulcer) –> high risk of corneal melt.

34
Q

what is HSV - disciform keratitis?

A

Secondary stromal edema due to an inflammatory response to viral antigen or live virus within the corneal endothelium.

35
Q

signs of HSV - disiform keratitis?

A
  • central, disc-shaped endothelial defect with stromal edema. — may have microcyst.
  • may also have uveitis – overlying keratic precipitates (KPs) & AC rxn.
36
Q

what is HSV - neurotrophic keratitis?

A
  • Results from reduced corneal innervation and decreased tear secretion, leading to poor corneal wound healing.
37
Q

signs of HSV - neurotrophic keratitis?

A
  • decrease CN5 - V1 sensitivity.
  • appears as an oval defect with smooth borders.
38
Q

w/u for HSV-1?

A

corneal scraping to be evaluated with Giemsa Stain.

39
Q

what stage is most severe in HSV keratitis?

A

stromal kertatitis –> leads to scarring or corneal melt.

40
Q

tx/managment for HSV1 keratitis?

A

tx depends on the what classification:
* epithelial keratitis – oral antivirals; Acyclovir – 400mg po 5x/day x 7 days or Valacyclovir (valtrex) – 500mg po TID x 7 days or famiciclovir 250mg po TID x 7days.
Topical antivirals; ganciclovir (zirgen) 5x/day or Trifluridine (viroptic) 9x/day.

  • stromal & disciform keratitis – topical steroid to reduce inflammation + oral antiviral + topical cycloplegic if uveitis.
  • neurotrophic keratitis – PF ATs q1h, ATs oinment qhs, punctual plugs. Abx if corneal ulcer present.
  • f/u one day
41
Q

what is herpes zoster virus (HZV)

A

Viral infection caused by varicella zoster virus (VZV) – same virus that cause chickenpox.

42
Q

where does HZV lay dormant?

A

dorsal root ganglion and other neural cell bodies.

43
Q

what is recurrent HZV?

A

it is reactivation of the latent infection which manifest anywhere in the body but follows affected dermatomes.

44
Q

When HZV reactivates along the ophthalmic branch (V1) of trigeminal nerve (CN5) it is called ___?

A

herpes zoster ophthalmicus (HZO).

45
Q

HZO can involve any or all of V1 branches. If it involves frontal nerve of V1, what signs can be seen?

A

vesicles on forehead

46
Q

HZO can involve any or all of V1 branches. If it involves nasociliary nerve of V1, what signs can be seen?

A

vesicles on tip of nose (hutchinson sign).

47
Q

prodrome HZV signs?

A

Pre-zoster (prodrome) signs:
* Malaise
* Fever
* Fatigue
* Itching/burning skin

48
Q

active HZO signs?

A

Hutchinson’s sign

Blepharoconjunctivits

Cornea involvement:
* Pseudo-dendritic keratitis – does not have terminall bulbs.
* interstitial keratitis – stromal infiltrate w/ vascularization but no epi defect.
* disciform keratitis – central, disc-shaped endothelial defect with stromal edema.
* neurotrophic keratitis – appears as an oval defect with smooth borders.

Exposure keratopathy

uveitis (iritis + AC rxn + KPs)

Posterior segment:
* Retinitis – can be acute retinal necrosis (ARN) - coalescent patches of retinal necrosis.

49
Q

what does HZV pseudodendrite stain with?

A

rose bengal & do not stain with NaFl

50
Q

what are post-zoster signs?

A

Characterized by post-herpetic neuralgia (PHN).
* pain, numbness, dysesthesia, allodynia persisting beyond 1 month after rash resolution.

51
Q

tx/mangement of HZV?

A

tx depends on the what classification:
* epithelial keratitis – oral antivirals; Acyclovir – 800mg po 5x/day x 7 days or Valacyclovir (valtrex) – 1000mg po TID x 7 days or famiciclovir 500mg po TID x 7days.

  • stromal & disciform keratitis – topical steroid to reduce inflammation + oral antiviral + topical cycloplegic if uveitis.
  • neurotrophic keratitis – PF ATs q1h, ATs oinment qhs, punctual plugs. Abx if corneal ulcer present.
  • f/u one day
52
Q

Is staph marginal keratitis infectious or sterile?

A

IT IS NOT INFECTIOUS IT IS AN INFLAMMATORY RXN.

53
Q

What is staph marginal keratitis?

A

characterized by peripheral cornea stromal infiltration which are often associated with epithelium break down and ulceration.

54
Q

what causes staph marginal keratitis?

A
  • Inflammatory rxn against staphylococcal antigens (rather than a direct staph infection of the cornea) — triggers a type 3 hypersensitivity rxn.
55
Q

what are symptoms of of staph marginal keratitis?

A
  • photophobia
  • pain
  • Tearing
  • Redness
56
Q

signs of staph marginal keratitis?

A
  • SEI’s at limbal margin – SEI’s can coalesce and spread circumferentially.
  • Small epithelial defect (smaller than infiltrate) overlying infiltrate.
  • Focal conjunctival hyperemia.
57
Q

tx for staph marginal keratitis?

A

Lid hygiene and warm compresses.

Topical antibiotics
* Vigamox QID.
* Erythromycin ung qhs.
* Bacitracin ung.

Topical steroids
* Pred forte qid
* FML qid
* Lotemax QID

Combination
* Tobradex QID – react really well to it.

CORNEA ANOMALIES (6 decks)

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