Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Introduction to Eye Disease - Year 2 > Keratitis > Flashcards

Keratitis Flashcards

1
Q

What are the infectious causes of keratitis?

A

Bacteria

Virus

Protozoa

Fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the non-infectious causes of keratitis?

A

Inflammatory Exposure Iatrogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is iatrogenic?

A

Something resulting from medical treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the five layers of the cornea?

A

Epithelium Bowmans membrane Stroma Descemet’s membrane Endothelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does keratitis mean?

A

Keratitis means inflammation of the cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the term microbial keratits refer to?

A

Bacterial Keratitis

Fungal keratitis

Keratitis caused by a protozoa

(the term microbial keratitis is reserved for all infectious keratitis but not viral keratitis).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the risk factors for microbial keratitis?

A

Trauma, Contct lens wear , surgery, ocular surface disease, immunosupresion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is microbial keratitis a medical emergency?

A

YES - it is a sight threatening opthalmic emergency.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Is keratitis a sight threatening disease?

A

Anything that comprimises the itegrit f thecorea isa sight threatening disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the most common cause of microbial keratitis?

A

Bacterial Corneal pathogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Is gram positive or negative bacteria most common in contact lens associated keratitis?

A

Gram negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Is gram positive or negative bacteria most common in NON-contact lens associated keratitis?

A

Gram positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the risk factors for bacterial keratitis?

A
  • contact lenses - increased incidence in contact lens wearers.
  • poor contact lens hygiene is a major risk factor!
  • in non contact lens wearers risk fators are:
  • immunosupression
  • ocular surface disease
  • trauma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the signs of microbial keratitis?

A

–> Inflitrate (as can be seen in the picture):

  • generally central
  • large >1mm
  • location is anterior to mid-stromal
  • full thickness epithelial loss

—> severe hyperamia

—> Anetrior Chamber reaction

  • inflammatory cells, flare to form hypopyon (a layer of white blood cells)

—> Lid oedema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the symptoms of microbial keratitis?

A
  • Unilateral
  • Moderate to severe pain, rapid onset
  • Reduced vision (-this depends on where the location of the lesion is i.e. a peripheral lesion is going to affect vision less - look at the picture for reference)
  • Photophobia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How do we manage microbial keratitis?

A
  • Immediately discontinuation of lens wear
  • Refer to A&E (specialist unit)

–corneal scrape or biopsy to determine specific microbe responsible (gold standard/reference treatment)

–Intensive anti-microbial treatment

Typically used is:

•A group of antibiotics called Fluoroquinolone antibiotics (these have strong gram negative tendencies) - an example of which is levofloxacin.

–close monitoring ( to make sure right drug was used for right microbe and that the sensitivity of the drug was correct )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does a corneal scrape take place?

A

A hypodermic needle is used not only to scrape the surface but right at the back of the lesion ( bacteria tend to reside at the back of the lesion). This scraping can be seen in the image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Once we have a corneal scrapping what do we do?

A

Place the scrapping in different growth mediums to determine what the microbe is.

e.g. the following growth mediums are used to find the following microbes

  • A. Saboraud agar (fungi)
  • B. Chocolate agar (fastidious microorganisms, particularly Haemophilus and Neisseria )
  • C. Blood agar (Streptococci)
  • D. Thioglycolate broth (differentiates between aerobes and anaerobes)
  • E. Viral transport media

The letters corrolate with the image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How can we determine the sensitivity of a bacterium to an antiobiotic?

A

We place our bacteria in an agar dish. We then add our antibiotic disks.

The zones of inhibition of bacterial growth around the antibiotic disk indicates the sensitivity. Larger disk = more sensitivity of that bacteria to that antibiotic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Who is microbial keratitis caused by acanthamoeba most common in?

A

Contact lens wearers- over 90% of cases are contact lens wearers (soft contact lenses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the risk factors for microbial keratitis caused by acanthoeba (2)?

A

Swimming or showering in contact lenses (use of tap water)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is acanthamoeba?

A

A free living protozoa which can be found in domestic water supplies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are symptoms of microbial keratitis caused by acanthamoeba?

A

Intense pain - even early on.

24
Q

What are signs of Microbial Keratitis caused by acanthamoeba?

A

Radial perineuritis - this means infiltration around corneal nerves

Anterior stromal infiltrates

Anterior Chamber activity/inflammation

Corneal oedema

Eventually (in progressed/late acanthamoeba keratitis), ring infiltrate forms (as can be seen in the image).

Perforation

25
Q

How do we manage microbial keratitis that is caused by acanthamoeba?

A

Immediate referral to ophthalmologist

Biopsy and culture ( to find out microbe responsible)

Treated with biguanides (PHMB or chlorhexadine) and or diamidines (propamidine) - these are basically disinfectants that kill the acanthamoeba in situ.

26
Q

What is the aetiology of fungal keratitis (4)?

A
  • Rare in Uk: caused by moulds (Aspergillus; Fusarium) or yeasts (Candida)
  • Common in patients from warm climate
  • Suspect if following trauma whilst gardening
  • Recent links with CL care products
27
Q

What is a difficulty in diagnosing fungal keratitis?

A

•Signs are similar to bacterial keratitis initially thus it is misdiagnosed.

28
Q

What is the management for fungal keratitis (2)?

A
  • Antifungals ( only get them from special pharmacies).
  • Often requires a corneal graft
29
Q

What does early acanthamoeba look like?

A

You see these dendritic (branched) lesions.

30
Q

What is the most common group of viruses that cause corneal infections?

A

The Herpes family of Viruses - e.g. the Herpes Simplex Virus (HSV) and the Varicella Zoster Virus (VZV) (chicken pox virus).

31
Q

What are the two types of Herpes Simplex Virus?

A

HSV-1 & HSV-2.

(HSV-2 is the one that causes genital herpes)

(HSV-1 causes cold sores)

32
Q

In children what does Varicella Zoster Virus (VZV) cause?

A

Chicken Pox

33
Q

What does the reactivation of Varicella Zoster Virus (VZV) in adults cause?

A

Shingles

34
Q

In ophthalmic shingles (caused by Varicella Zoster Virus (VZV)) is the cornea involved?

A

Most commonly yes - ( in 65% of cases)

35
Q

What is the aetiology of Herpes simplex keratitis (Herpatic Keratitis)?

A

(It is thought 90% of the population is seropositive (dormant in cells))

HSV-1 virus

•Primary infection occurs in childhood causing blepharoconjunctivitis (occasionally with corneal involvement).

36
Q

What is orofacial ulceration?

A

A fancy name for cold sores

37
Q

What are signs and symptoms of Herpes Simplex Keratitis?

A
  • Eyelid rash (clear vesicles)
  • STARTS as Punctate keratitis leading to dendritic ulcer which can become:

-Geographical ulcer

•Stromal keratitis: oedema, infiltration, vascularisation leading to scarring

–Disciform keratitis (basically having stromal and epithelial keratitis)

38
Q

What is the treatment for Herpes Simplex Keratitis (2)?

A
  • Anti-viral eye drops - for dendritic ulcer
  • May require steroids for stromal disease ( for the late/progressed disease)
39
Q

Can Herpes Simplex Keratitis be recurrent?

A

Yes - sadly as it lays dormant it can keep being reactivated even after having previously been treated.

40
Q

What is adenoviral keratitis caused by?

A

A complication of adenoviral conjunctivitis.

41
Q

What is a sign of adenoviral keratitis?

A

Focal sub-epithelial infiltrates

42
Q

What is the treatment for adenoviral keratitis?

A
  • usually, resolve themselves, however….

•corticosteroids if severe and a threat to vision

43
Q

What are the mechanisms of bacterial pathogenicity?

(how are bacteria pathogenic?)

A
  • Bacteria produce damage through the colonisation of the body surface and release of toxins.
  • Bacteria can cause damage by invasion and subsequent multiplication in the tissues.
44
Q

What are common corneal responses to bacterial toxins in contact lens wearers?

A
  • Contact lens associated red eye (CLARE) (hyperaemia)
  • Marginal keratitis
  • Contact lens peripheral ulcer (CLPU)
45
Q

If you took a biposy of an ulcer caused by bacterial toxins would you be able to identify the microbe responsible?

A

No - the ulcer is just a response essentially to a harmful foreign body (a.k.a the bacterial toxin).

46
Q

Are corneal responses to bacterial toxins deemed as infectious or non-infectious keratitis?

A

Non-infectious

47
Q

What’s the treatment for a contact lens peripheral ulcer?

A

To stop using contacts for a while - the ulcer then usually sorts itself out. (If you got the diagnosis right!).

48
Q

What is marginal keratitis?

A

•Inflammatory response to bacterial toxins on lids

In the picture the patient had bacterial blepharitis- the bacteria on the lids released toxins which caused the keratitis you can see as the hyperaemia on the ocular surface.

49
Q

How is marginal Keratitis managed?

A

Managed with combinations of topical steroid and antibiotics +/ lid hygiene

50
Q

Is marginal keratitis deemed infectious?

A

No its non-infectious.

51
Q

What is exposure keratitis?

A

Where exposure of the cornea leads to desiccation and surface damage.

52
Q

What are some common aetiologies of exposure keratitis (4)?

A
  • Thyroid eye disease
  • Facial palsy
  • Ectropion
  • Lagophthalmos
53
Q

Why do eye drops need to be preserved with preservatives?

A

To avoid bacterial contamination

54
Q

What is potentially dangerous about preservatives in eye drops?

A

These preservatives are potentially toxic to ocular surfaces (corneal epithelial toxicity) - particularly for patients with chronic conditions that are using these eye drops for long periods of time.

55
Q

What preservative commonly causes corneal epithelial toxicity and thus what conditions may it be associated with (2)?

A

Benzalkonium chloride (BAK)

It is commonly associated with the following conditions:

  • Punctate keratopathy
  • May be associated with conjunctival reaction (hyperaemia, follicles)
56
Q

What type of a disease is corneal epithelial toxicity caused by preservatives in eye drops prescribed to patients?

A

An Iatrogenic one - as it is caused by medical professionals/ what they prescribe.

Introduction to Eye Disease - Year 2 (40 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions