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Duke Elder Exam Prep > Corneal Pathologies > Flashcards

Corneal Pathologies Flashcards

1
Q

What is bacterial keratitis?

A

This is a bacterial infection of the cornea which can be sight threatening, although it is quite common.

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2
Q

What group are most likely to get bacterial keratitis?

A

Lens wearers

Soft lenses > rigid lens

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3
Q

What are the common infective organisms of bacterial keratitis?

A

Pseudomonas Aeruginosa
Staph Aureus
Streptococcus

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4
Q

List some clinical features of bacterial keratitis:

A 
Unilateral, sudden onset of pain 
Redness 
Photophobia 
Discharge (purulent of mucopurulent)
Circumcorneal injections
White infiltrates epithelial and stromal involvement
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5
Q

What is a clinical feature of serious keratitis?

A

Hypopyon formation and anterior chamber cells

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6
Q

What is a serious complication of bacterial keratitis?

A

Corneal perforation

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7
Q

What organisms are most likely when corneal perforation occurs?

A

Neisseria Gonorrhoea
Corynebacterium diphtheriae
Haemophilus influenza

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8
Q

What is the media and staining for bacterial keratitis?

A

Blood/chocolate agar - gram stain

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9
Q

What is the media and staining for fungal keratitis?

A

Sabouraud agar and gram stain

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10
Q

What is the media and staining for mycobacterium?

A

Lowenstein Jensen medium

Zeihl-Neelsen stain

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11
Q

What is the media and staining for Acanthamoeba?

A

Non-nutrient agar with Escherichia coli

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12
Q

What investigations should be done in corneal keratitis?

A

Cornea scraping

Gram stain and cultures

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13
Q

What is the management for bacterial keratitis?

A

Topical broad spectrum antibiotics

Typically use fluoroquinolones

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14
Q

What is the commonest cause of fungal keratitis and what group of patients are they often seen in?

A

Candida

Immunocompromised patients e.g. HIV

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15
Q

What organisms are common in fungal keratitis following ocular trauma?

A

Filamentous fungi e.g.
Aspergillus
fusarium

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16
Q

What is a specific sign of candida keratitis?

A

Small ulcer with an expanding infiltrate in a collar stud formation

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17
Q

What is a specific sign of filamentous keratitis?

A

Feathery branching like infiltrate pattern

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18
Q

What is the appropriate management of fungal keratitis?

A

Natamycin drops - for filamentous

Voriconazole or amphotericin B drops for candida

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19
Q

What is the main risk factor for developing acanthamoeba keratitis and give some clinical features of it?

A

Improper lens hygiene.

Patients present with pain disproportionate to their clinical signs. Associated with photophobia and blurred vision.

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20
Q

What are some later signs of an acanthamoeba keratitis?

A

Perineural infiltrates

ring shaped stromal infiltrates

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21
Q

How is acanthamoeba keratitis managed?

A

Confocal microscopy can identify presence of amoebic cysts

Topical polyhexamethylene biguanide or chlorhexidine

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22
Q

What vital infection which initially causes blepharoconjunctivitis can remain latent and cause keratitis later?

A

Herpes simplex virus

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23
Q

Where would latent HSV live?

A

in the trigeminal ganglion

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24
Q

Keratitis affects what layers of the cornea?

A

It can affect any of these:
Epithelial
Stromal
Endothelial

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25
Q

What are some signs of epithelial keratitis?

A

Superficial punctate keratitis which causes a stellate erosion –> later becomes a classic dendritic ulcer. This can be seen clearly with fluorescein
Reduced corneal sensation

26
Q

When would disciform endothelial keratitis usually occur?

A

In HSV antigen hypersensitivity - not so much in reactivation
Insidious onset of painless decreased visual acuity (dVA)

27
Q

What are some signs of disciform keratitis?

A

Central circular stromal oedema
Mild anterior chamber activity
Keratitic precipitates
Wessely ring

28
Q

What would be seen on giemsa staining for disciform keratitis?

A

Multinuclear giant cells

29
Q

What treatment options are their for the different HSV keratitis?

A

Endothelial / disciform - oral aciclovir 400mg 5x daily
- avoid topical steroids
Epithelial - topical acyclovir
- avoid steroids

30
Q

Why should steroids be avoided in keratitis before epithelium is intact?

A

Risk of geographic ulcer and corneal perforation

31
Q

What does herpes zoster opthalmicus refer to?

A

This is when shingles (reactivation of VZV) affects the CNV1 dermatome

32
Q

What is Hutchinson’s sign?

A

this is when the tip of the nose is involved in shingles - indicates higher likelihood of ocular involvement due to the nasociliary nerve involvement

33
Q

What are some ophthalmic features of shingles?

A

Epithelial keratitis
Conjunctivitis
Elevated IOP
Stromal and disciform keratitis (less common)

34
Q

How is ophthalmic shingles managed?

A

Oral aciclovir 800mg 5x daily

Amitriptyline for neuropathic pain

35
Q

What does interstitial keratitis describe?

A

Underlying pathology of stromal inflammation +/- neovascularisation
Caused by an immune reaction to a foreign antigen

36
Q

What are the main features of interstitial keratitis?

A

Pain
Photophobia
Decreased visual acuity

37
Q

Give some causes of interstitial keratitis

A

congenital syphilis
Lyme disease
Viral (HSV, VZV, EBV)
Cogan syndrome

38
Q

What is significant about congenital syphilis keratitis as opposed to acquired?

A

Congenital is bilateral whereas acquired is usually unilateral
Often get the syphilis triad - interstitial keratitis, teeth notching and sensorineural deafness

39
Q

What is Cogan syndrome?

A

This is an autoimmune disorder which causes interstitial keratitis with sensorineural hearing loss, vertigo and tinnitus. Can be complicated by polyarteritis nodosa

40
Q

This is a type of peripheral corneal inflammation due to a type 3 hypersensitivity reaction t a staphylococcal exotoxin which is associated with rosacea and blepharitis.

A

Marginal keratitis

41
Q

How is marginal keratitis managed?

A

topical steroids (mild) and lid hygiene

42
Q

Give some features of marginal keratitis:

A

Epiphora
Photophobia
Chronic blepharitis
Sub epithelial infiltrates which are separated from the limbus by a clear zone
In region where eyelids come into contact with the cornea

43
Q

This is an umbrella diagnosis for a group of conditions which lead to peripheral corneal thinning and is often associated with RA:

A

Peripheral ulcerative keratitis

44
Q

What are some clinical features of peripheral ulcerative keratitis and how is it managed?

A

Begins peripherally but eventually reaches the centre of the cornea, end stage = thin vascular stroma
(Epi)scleritis may be present
interpalpebral peripheral corneal stromal thinning with an epithelial defect
Manage: oral prednisolone +/- systemic immunosuppression

45
Q

What ocular symptoms can acne rosacea cause (in ocular rosacea)

A 
Dry red eyes with epiphora and photophobia
telangiectasia and posterior blepharitis
Conjunctival hyperaemia 
Marginal keratitis
inferior corneal thinning
Superficial erosions
46
Q

How is ocular rosacea managed?

A

Optic hygiene
Topical lubrication
Oral tetracycline

47
Q

Define filamentary keratitis:

A

This is a condition where the corneal epithelium degenerates, leaving strands (filaments) and mucus to adhere to the corneal surface
May see ‘comma shaped’ lesions that move up and down

48
Q

This is a bilateral and asymmetrical condition which is characterised by central stromal thinning and apical protrusion of the cornea:

A

Keratoconus

49
Q

Keratoconus is associated with what conditions/

A 
Marfans
Downs
Ehlers-Danlos
Retinitis pigmentosa
History of atopy
50
Q

What are some features of keratoconus?

A

Irregular astigmatism
Downward gaze causes lower eyelid protrusion (Munson sign)
Slit lamp showing vertical striations on stroma
Fleisher’s ring
Oil drop reflex
Scissoring reflex on retinoscopy

51
Q

What is a complication of keratoconus?

A

Acute hydrops - a tear in the Descemet layer leading to corneal oedema

52
Q

What investigation would be appropriate for keratoconus?

A

Keratometry

Video keratography

53
Q

How is keratoconus managed?

A

Spectacles
Rigid/hard lenses OR corneal collaged cross inking using riboflavin drops or UVA
Penetrating or deep anterior lamellar keratoplasty
(LASIK generally contraindication)

54
Q

Define microphthalmia:

A

A condition in which the whole eye is smaller than average by at least two standard deviations
Can be simple or complex
Increased risk of retinal detachment

55
Q

Simple microphthalmia features:

A 
Bilateral involvement
Associated with:
- closed angle glaucoma
-uveal effusion syndrome
- Hypermetropia
- Amblyopia
- strabismus
56
Q

Complex microphthalmia features:

A

A small eye associated with other abnormalities e.g. orbital cysts or colobomas
Associated w/ foetal alcohol syndrome and IU infections

57
Q

Define Wilson’s disease:

A

This is an AR genetic disorder in which there is copper deposition in the body, mainly the liver brain and eyes

58
Q

Give some features of Wilson’s disease:

A

Hepatic cirrhosis
Keyser-Fleischer rings
Movement disorders and ataxia
Anterior subcapsular sunflower cataracts

59
Q

What is a sign of calcium deposition in the bowman’s layer?

A

Band keratopathy

60
Q

Give some causes of band keratopathy:

A 
Old age
Idiopathic
Hyperkalaemia and renal failure
Silicone oil
Chronic anterior uveitis
61
Q

How is band keratopathy managed?

A

Treat underlying cause

Chelation with EDTA

Duke Elder Exam Prep (18 decks)

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