Lecture 5 - Infectious Keratitis

Corneal ulcers are an example of __________ keratitis

bacterial

CLPU is an example of __________ keratitis

bactrial

Staphylococcal marginal keratitis is an example of __________ keratitis

bacterial

Phlyctenular keratoconjunctivitis is an example of __________ keratitis

bacterial

Acanthamoeba keratitis is an example of __________ keratitis

parasitic

Up to ___% caused by Pseudomonas aeruginosa

70%

There is __________ cases of bacterial keratitis annually in the US

30,000

List the 9 risk factors of bacterial keratitis

- CL wear

- Ocular surface disease

- Neurotrophic keratitis

- Ocular trauma

- Immunocompromise

- DM

- RA

- Alcohol or drug use

- Vitamin deficiency

CLPU's are most common in patients who:

sleep in their lenses

CLPU is associated with colonization on CL surfaces by Gram(+/-) bacteria

(+)

List the 4 most common species that cause bacterial keratitis

Staphylococcus aureus

Staphylococcus epidermidis

Streptococcus pneumonia

Pseudomonas aeuruginosa

Which conditions form "sterile ulcers"

- CLPU

- Staph marginal

- Phlyctenular

CLPU is generally (uni/bi)lateral

unilateral

What is the most common species to cause CLPU

staph

CLPU stains with NaFl in the (acute/chronic) phase

acute

(d/t epithelial loss)

In CLPU, epithelial regeneration occurs over __-__ days leaving a circular scar, they may gradually fade over __-__months

epi regeneration over 1-2 days

may gradually fade over 3-6 month

At which clock hours do you typical see Staph Marginal Keratitis

4, 8 , 10, 2

(where the lid crosses the cornea)

image slide 5

Staph Marginal Keratitis is almost always presenting in the presence of longstanding:

blepharitis

Phlyctenular Keratoconjunctivitis occurs d/t a type ___ hypersensitivity reaction

type IV

What is the most common causative agent of Phlyctenular Keratoconjunctivitis in the US

Staphylococcus aureus

What is the most common causative agent of Phlyctenular Keratoconjunctivitis historically/in places other than the US

TB

Phlyctenular Keratoconjunctivitis is more commonly seen in (children/adults)

children

List the 3 fungal organisms that cause Fungal Keratitis

• Fusarium

• Candida

• Aspergillus

List the 5 things that increase a persons risk of developing a Fungal Keratitis

• CL wear

• Trauma (organic matter)

• OSD

• Corneal surgery

• Immunosuppressive therapy (including topical steroids)

Give 2 reasons why you cant depend on the finding of feathery lesions alone to dx a Fungal Keratitis

- does not look feathery on day 1

- Candida is a yeast and therefore will not present with feathery lesion

(T/F) Fungal Keratitis is often misdiagnosed & treated

TRUE

this is because the feathery lesions are not present in the acute phases, so looks like bacterial infection until it doesnt

What are the 2 forms of Acanthamoeba, which one is very challenging to eliminate

trophozoite & cyst

cyst challenging

List the 2 key corneal findings seen in Acanthamoeba Keratitis

- radial keratoneuritis

- ring infiltrate

images slide 9

How does the action on corneal nerves differ from Acanthamoeba infection and Herpetic infection

Acanthamoeba:

causing corneal nerve inflammation which leads to extreme pain

Herpes:

causing corneal nerve death which leads to decreased pain and corneal sensitivity

_________ is the main sx for infiltrative conditions

redness + FBS

_________ is the main sx for infectious conditions

pain (6/10)

_________ is the main sx for acanthameoba conditions

severe pain (20/10)

If a pt present and sx are significantly worse than sn, be very concerned for ____________

Acanthamoeba

Pt presenting with c/o a "white spot" on the eye is more likely in cases other than ___________, why

Acanthamoeba

white spot (infiltration) usually takes time to occur and acanthamoeba pt will be in so much pain they will come before that forms

List the 3 measurement of the lesion that are made on clinical exam

• Size of epithelial defect

• Size of infiltrate

• Estimation of depth of ulceration (loss of stroma in %)

Once an ulcer/infiltrate has healed, pt are often left with (regular/irregular) astigmatism d/t:

irregular astigmatism

d/t scarring

Give the expected clinical findings of a Sterile Ulcer:

- size

- location

- epi defect

- discharge

- pain

- AC reaction

- lid involvement

- size: small <1-1.5mm

- location: peripheral

- epi defect: minimal

infiltrate>ulceration

- discharge: (-)

- pain: more FBS

- AC reaction: 0-trace

- lid involvement: (-)

Give the expected clinical findings of a Bacterial Ulcer:

- size

- location

- epi defect

- discharge

- pain

- AC reaction

- lid involvement

- size: larger >1mm

- location: central

- epi defect: significant

infiltration=ulceration

- discharge: mucopurulent

- pain: (+) & photophobia

- AC reaction: (+), mild

- lid involvement: edema

Give the expected clinical findings of a Fungal Ulcer:

- size

- location

- epi defect

- discharge

- pain

- AC reaction

- lid involvement

- size: larger >1mm

- location: central

- epi defect: intact but elevated

- discharge: (+/-)

- pain: (+) & photophobia

- AC reaction: (+), severe... hypopyon common

- lid involvement: edema

Satellite lesions are a sign of __________ keratits

Fungal Keratitis

What AC reaction do you expecting in Acanthamoeba Keratitis

moderate - severe

hypopyon possible

There is a (papillary/follicular) conjunctival reaction in Bacterial Keratitis

papillary

There is a (papillary/follicular) conjunctival reaction in Acanthamoeba Keratitis

follicular

There is a (papillary/follicular) conjunctival reaction in Fungal Keratitis

generally mixed

What are the expected pupillary response changes in an infiltrative keratitis case

none

What are the expected pupillary response changes in an infectious keratitis case

- constriction

- poorly reactive

- sluggish response

Where do you expect conjunctival injection in an infectious keratitis case

360°, 3-4+ injection

Where do you expect conjunctival injection in an infiltrative keratitis case

localize around the lesion

Under what 8 circumstances should you perform a corneal culture

• Large ulcer >2mm in diameter

• Involves the deep stroma

• Involves central cornea near visual axis

• Exam or Hx that suggests an unusual pathogen

• Lesion with suspicious characteristics

• Post-surgical patients

• Monocular patients

• Immunocompromised patients

If suspect/dx ____________ keratitis, you should order labs & x-ray to r/o _____

Phlyctenular to r/o TB

AAO recommends corneal culture of ulcers larger than ____ in diameter

2mm

Presence of a raised or gray ulcer is suggestive of _______________ keratitis

Fungal

Presence of descemetocele is suggestive of _______________ keratitis

Acanthamoeba

(T/F) Microbial Keratitis is an ocular emergency

TRUE

(T/F) Patching/BCL is a good manangement strategy for microbial keratitis pt

FALSE

NEVER patch or place BCL on pt

If your CL pt is dx with a microbial keratitis case, you can let them know they will be out of CLs for __-__ months depending on size & location of ulcer

6-12 months

(T/F) Microbial Keratitis has a good prognosis if treatment initiated early in disease process

TRUE

Steroids should. NEVER be used in the case of _________ infection

fungal

What was concluded from the Steroids for Corneal Ulcers Trial

steroids are beneficial as an adjunctive therapy once you have sterilization of an ulcer

DO NOT use steroids on open ulcer

- never give steroids on day 1*

What is the purpose os steroid therapy in Microbial Ulcers, what is the drawback

prevents scarring

but using too early can lead to reinfeciton so important to give sufficient time for antibiotic to sterilize ulcer or epi defect is resolved before beginning therapy

List the 8 clinical signs of improvement

• Blunting of the perimeter of the stromal infiltrate

• Decreased infiltration (density or size)

• Decreased stromal edema

• Decreased AC inflammation

• Reepithelialization of corneal epi defect

• Improvement in painful sx

• Corneal vascularization

• Scarring