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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
What are some signs of epithelial keratitis?
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
When would disciform endothelial keratitis usually occur?
In HSV antigen hypersensitivity - not so much in reactivation Insidious onset of painless decreased visual acuity (dVA)
27
What are some signs of disciform keratitis?
Central circular stromal oedema Mild anterior chamber activity Keratitic precipitates Wessely ring
28
What would be seen on giemsa staining for disciform keratitis?
Multinuclear giant cells
29
What treatment options are their for the different HSV keratitis?
Endothelial / disciform - oral aciclovir 400mg 5x daily - avoid topical steroids Epithelial - topical acyclovir - avoid steroids
30
Why should steroids be avoided in keratitis before epithelium is intact?
Risk of geographic ulcer and corneal perforation
31
What does herpes zoster opthalmicus refer to?
This is when shingles (reactivation of VZV) affects the CNV1 dermatome
32
What is Hutchinson's sign?
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
What are some ophthalmic features of shingles?
Epithelial keratitis Conjunctivitis Elevated IOP Stromal and disciform keratitis (less common)
34
How is ophthalmic shingles managed?
Oral aciclovir 800mg 5x daily | Amitriptyline for neuropathic pain
35
What does interstitial keratitis describe?
Underlying pathology of stromal inflammation +/- neovascularisation Caused by an immune reaction to a foreign antigen
36
What are the main features of interstitial keratitis?
Pain Photophobia Decreased visual acuity
37
Give some causes of interstitial keratitis
congenital syphilis Lyme disease Viral (HSV, VZV, EBV) Cogan syndrome
38
What is significant about congenital syphilis keratitis as opposed to acquired?
Congenital is bilateral whereas acquired is usually unilateral Often get the syphilis triad - interstitial keratitis, teeth notching and sensorineural deafness
39
What is Cogan syndrome?
This is an autoimmune disorder which causes interstitial keratitis with sensorineural hearing loss, vertigo and tinnitus. Can be complicated by polyarteritis nodosa
40
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.
Marginal keratitis
41
How is marginal keratitis managed?
topical steroids (mild) and lid hygiene
42
Give some features of marginal keratitis:
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
This is an umbrella diagnosis for a group of conditions which lead to peripheral corneal thinning and is often associated with RA:
Peripheral ulcerative keratitis
44
What are some clinical features of peripheral ulcerative keratitis and how is it managed?
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
What ocular symptoms can acne rosacea cause (in ocular rosacea)
``` Dry red eyes with epiphora and photophobia telangiectasia and posterior blepharitis Conjunctival hyperaemia Marginal keratitis inferior corneal thinning Superficial erosions ```
46
How is ocular rosacea managed?
Optic hygiene Topical lubrication Oral tetracycline
47
Define filamentary keratitis:
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
This is a bilateral and asymmetrical condition which is characterised by central stromal thinning and apical protrusion of the cornea:
Keratoconus
49
Keratoconus is associated with what conditions/
``` Marfans Downs Ehlers-Danlos Retinitis pigmentosa History of atopy ```
50
What are some features of keratoconus?
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
What is a complication of keratoconus?
Acute hydrops - a tear in the Descemet layer leading to corneal oedema
52
What investigation would be appropriate for keratoconus?
Keratometry | Video keratography
53
How is keratoconus managed?
Spectacles Rigid/hard lenses OR corneal collaged cross inking using riboflavin drops or UVA Penetrating or deep anterior lamellar keratoplasty (LASIK generally contraindication)
54
Define microphthalmia:
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
Simple microphthalmia features:
``` Bilateral involvement Associated with: - closed angle glaucoma -uveal effusion syndrome - Hypermetropia - Amblyopia - strabismus ```
56
Complex microphthalmia features:
A small eye associated with other abnormalities e.g. orbital cysts or colobomas Associated w/ foetal alcohol syndrome and IU infections
57
Define Wilson's disease:
This is an AR genetic disorder in which there is copper deposition in the body, mainly the liver brain and eyes
58
Give some features of Wilson's disease:
Hepatic cirrhosis Keyser-Fleischer rings Movement disorders and ataxia Anterior subcapsular sunflower cataracts
59
What is a sign of calcium deposition in the bowman's layer?
Band keratopathy
60
Give some causes of band keratopathy:
``` Old age Idiopathic Hyperkalaemia and renal failure Silicone oil Chronic anterior uveitis ```
61
How is band keratopathy managed?
Treat underlying cause | Chelation with EDTA

Duke Elder Exam Prep (18 decks)

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