Corneal Dystrophies Flashcards

1
Q

What are the five layers of the cornea?

A

Corneal Epithelium

Bowman’s membrane

Corneal Stroma

Descements Membrane

Corneal Endothelium

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2
Q

Which layers of the cornea do we mainly have a problem with, if any?

A

Corneal Epithelium

Corneal Stroma

Corneal Endothelium

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3
Q

What is Epithelial basement mebrane dystrophy?

A

The epithelium is very weak and doesn’t stick to bowman’s layer underneath.

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4
Q

What are the symptoms associated with a scratch on the cornea if a patient has Epithelial basement membrane dystrophy?

A

Pain

Watering - epiphora

Photophobia + glare

Waking with a painful eye

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5
Q

How may epithelial basement membrane dystrophy appear under a slit lamp?

A

Epithelial Micro-cysts

As tiny dots or ‘cogans’ in the corneal epithelium - these are basically patches where the cornea has healed itself following any abrasions.

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6
Q

What is the acute management of a nasty scratch on the cornea?

A

Anaesthetics - for the pain

Antibiotics - as a preventative measure

Perhaps mydriatics and cyloplegics to rest the eye - when there is a scratch on the cornea the ciliary muscle goes into spasm.

Perhaps a bandage contact lenses

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7
Q

How would we manage recurrent epithelial erosion syndrome (i.e. recurrent damage of the epithelium because it is weak)?

A
  • Debridement - basically take off the current epithelium which is already loose and hope that a new stronger one grows back.(OLD METHOD)
  • Anterior stromal puncture - puncture holes in the corneal eptihelium so the bowman’s layer has something to stick onto. (OLD METHOD)
  • Excimer laser PTK (phototherapeutic keratectomy)- resurfaces the cornea - it makes the cells of the bownman’s layer rougher so when epithelial cells regrow they have something to stick to. (CURRENTLY USED)
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8
Q

What is Reiss Buckler’s?

Is it unilateral or bilateral?

Is it common or rare?

What is it caused by?

A

A type of corneal dystrophy that affects the bowman’s membrane - it is caused by an autosomal dominant inheritance.

It is unilateral

It is very rare.

It is caused by abnormal collagen

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9
Q

True or False- Dystrophies are inherited conditions.

A

True

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10
Q

What are dystrophies?

A

Abnormal deposition of naturally occuring substances

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11
Q

What condition can be seen in the image below?

In whom is this condition prevalent?

What is this condition the result of?

What does this condition indicate?

A

Arcus Senilis

Those over the age of 50

This condition is the result of deposits of cholesterol esters and glycerides in the stroma

Indicates Raised Chloesterol

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12
Q

What do you need to know about granular dystrophy?

A

It is very rare.

Essentially granular deposits.

It is hereditary

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13
Q

What is macular dystrophy and what do you need to know about it?

A

Diffuse dots all across the surface of the cornea.

it is caused by an excess of naturally occuring material.

It is autosomal recessive.

[Macular is just latin for space]

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14
Q

What type of dystrophy is this and what is it caused by?

A

It is lattice dystrophy. It is an autosomal domiant condition. It is caused by a network of deposits.

It is a rare condition

[Despite having a corneal regraft it still reoccurs].

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15
Q

What condition is this?

A

Gelatinous Droplet Keratopathy

It is autsomal recessive.

Caused by Amyloid inbalance.

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16
Q

Whta type of dystrophy is this and what is it caused by?

A

VERY VERY RARE

17
Q

What does corneal Ectasia mean?

A

The cornea is buldging aka it is coming forward

18
Q

What is another name for corneal ectasia?

A

Keratoconus

19
Q

How may keratoconus be identified via retinoscopy and slit lamp?

A

As a scissor reflex in retinoscopy and an oil droplet flashback through ophthalmoscopy.

20
Q

What is the aetiology of Keratoconus?

A

udefective collagen cross-linking?

uincreased collagenolysis

  • reduced protein synthesis
  • defects in RNA translation
  • increased corneal compliance

ucorneal hysteresis

-iatrogenic – caused by LASIK laser eye surgery – this is where they take away parts of the cornea – if they take away too much they leave the px at risk of keratoconus – which occurs when the cornea is very thin and so susceptible to distortion.

21
Q

What are some associations of Keratoconus?

A

Px with the following conditions are more likely to have keratoconus:

  • atopic disease: vernal conjunctivitis, eczema, asthma
  • Down’s syndrome (trisomy 21)
  • eye rubbing
  • aniridia (congenital condition where you are missing the iris)
  • Retinitis pigmentosa
  • Leber’s congenital amaurosis
  • ectopia lentis
  • microcornea
  • blue sclera – osteogenesis imperfecta………………..
22
Q

What are signs of keratoconus?

A
23
Q

What is the managment of keratoconus?

A
  • Spectacles – however VA limited by irregular astigmatism
  • Gas Permeable Contact lenses succeed in 85% of cases
  • Collagen Cross-Linking (CCL, CXL, CCXL) – method of strengthening the corneea
  • Intacs to ‘reinforce’ mid-peripheral stroma

Corneal grafting

24
Q

True or False- In corneal grafts the entire cornea is removed and replaced

A

False - typically only the central 8mm are removed and replaced (the average cornea is 10-11mm wide).

25
Q

What is a keratoplasty?

A

A fancy way of saying a corneal regraft

26
Q

What is the difference between a pentrating keratoplasty and a deep lamellar keratoplasty (DLK)?

A

In a pentrating keratoplasty all of the central cornea is cut out and replaced. In a deep lamellar keratoplasty, the central cornea is cut out but the bottom endothelium isn’t and the new graft is placed ontop of that.

27
Q

What are possible advnatges of a deep lamellar keratoplasty?

A
28
Q

Do we need to worry about rejection with a corneal graft?

A

No thankfully not as there are no blood vessels in the cornea to bring the antibodies in

29
Q

What is a site of immune priviledge?

A

Sites that are able to tolerate introducing antigens without eliciating an inflammatory reaction - basically where risk of rejection is low

(i.e. the cornea)

30
Q

What are some examples of endothelial dystrophies?

A
  • Congenital Hereditary Endothelial Dystrophy (CHED)
  • Posterior polymorphous dystrophy (PPD)
  • Irido-corneal endothelial dystrophy (ICE)
  • Fuchs’ endothelial dystrophy
31
Q

Describe Posterior Polymorphous Dystrophy

A

Basically what appears to be tram lines in the endothelium.

It does not affect vision and so no treatment is needed.

It is autosomal dominant or recessive.

32
Q

Describe fuchs’ endothelial dystrophy and symptoms associated with it.

A

Autosomal dominant

  • Cornea guttata - (gutattata is latin for droplets)
  • Px experiences a loss of endothelial cells
  • pax is middle-age onwards
  • px expereinces stromal oedema
  • there isincreased corneal thickness
  • epithelial oedema is present
  • visual loss
  • erosion symptoms (so ephiphora, photophobia, glare pain etc)
33
Q

What is the managment for Fuchs Endothelial dystrophy?

A
  • dry the cornea – ‘hairdryer’ or 5% NaCl drops
  • bandage contact lenses
  • reduce IOP
  • replace endothelium (PK, Descemet’s stripping automated endothelial keratoplasty DSAEK, Descemet’s membrane endothelial keratoplasty DMEK)
34
Q
A