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Introduction to Eye Disease - Year 2 > Cataract > Flashcards

Cataract Flashcards

1
Q

Define Cataract

A

Any opacity of the crystalline lens or of its capsule

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2
Q

Describe the lens and its structure

A
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3
Q

In cataract what is the loss of transparency of the lens caused by?

A

A disorganisation of the lens fibre membrane and lens proteins.

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4
Q

What is the prevalence of cataract?

A
  • Leading cause of visual impairment worldwide -repsonsible for 47.9% (WHO 2016)
  • Prevalence increases with age - 2 out of 3 cases diagnosed > 70 years
  • 30% of people 65+ years have visually impairing cataract (VA<6/12) in at least one eye - A further 10% have already had surgery.

Most common age groups for cataract are:

  • 59% of 80 to 84 year old px have cataract.
  • 71% of 85+ years old Px have cataract.
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5
Q

What are cataract risk factors?

A
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6
Q

How do we classify cataract?

A
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7
Q

What are the different maturities (i.e. stages) of cataract?

A
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8
Q

What are the different age related cataracts (4)?

A
  1. Subcapsular Cataract- of which it can be Anterior or Posterior
  2. Nuclear Cataract
  3. Cortical (cuneiform) Cataract
  4. Christmas tree Cataract
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9
Q

Where are anterior and posterior subcaspular cataracts located?

A
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10
Q

What happens in Posterior Subcapsular Cataract (PSC)?

A

•Epithelial cells migrate to posterior pole where they link with lens fibres

There is then a breakdown of posterior cortex to form “globules”

Epithelial cells coalesce (come together) to form larger “bladder cells”

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11
Q

What can Posterior Subcapsular Cataract (PSC) be a side effect of?

A

Can be a side effect of steroid therapy

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12
Q

What uncontrolled conditon can increase the risk of Posterior Subcapsular Cataract (PSC)?

A

Uncontrolled diabetes increases the risk of Posterior Subcapsular Cataract (PSC).

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13
Q

In terms of looking for Posterior Subcapsular Cataract (PSC) why is it important to always make sure you use a slit lamp as well as direct ophthalmoscopy?

A

Posterior Subcapsular Cataract (PSC) is easily missed in direct ophthalmoscopy.

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14
Q

What are effects of Posterior Subcapsular Cataract (PSC) upon vision?

A

•Painless progressive loss of vision

  • It can have a devastating effect on vision - The smallest/minimum opacity would still cause a huge fall in acuity.

•VA will be worse in bright light (because pupil constricts in bright light thus extent of opacity is emphasised)

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15
Q

Will a pinhole improve vision in those with Posterior Subcapsular Cataract (PSC)?

A

A pinhole does not improve visual acuity for Pxs with Posterior Subcapsular Cataract

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16
Q

How may retinoscopy be affected by Posterior Subscapsular Cataract?

A

Retinoscopy may be difficult so you may need to work a little bit off axis.

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17
Q

How may direct ophthalmoscopy be affected by the presence of a Posterior Subcapsular Cataract (PSC)?

A

Although its easy to miss a PSC in direct ophthalmoscopy, the PSC may make it difficult to view the macula.

[At whihc point you would want to consider using indirect techniques instead]

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18
Q

Why does Posterior Subcapsular Cataract affect a Px’s vision so severely?

A
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19
Q

What does Nuclear Cataract / Nuclear Sclerosis affect?

A

The nucleus of the lens. There is a progressive hardening, yellowing and opacification of lens nucleus

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20
Q

What happens to the colour of the lens in Nuclear Sclerosis as the condition progresses?

A

Lens colour changes from yellow to brown as cataract progresses

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21
Q

How is vision affected by Nuclear Sclerosis?

A

There is vision loss due to light scatter and absorption (i.e. short wavelengths of light - blue light - are absorbed - this gives the nucleus a yellow appearance).

As the condition progresses the change in colour of the lens (from yellow to brown) causes a slight myopic shift (~0.5D) - [this causes an improvement in near vision which is why it is refered to as ‘second sight of the elderly’].

The yellowing of the lens also causes colour vision impairment whereby the nucleus acts as a yellow filter and transmission of blue light is reduced.

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22
Q

What does cortical cataract affect?

A

The cortex of the crystalline lens

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23
Q

What may cortical cataract also be called?

A

Cuneiform

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24
Q

What is a cortical cataract?

A

•Opacification due to scattering of light between regions of different refractive index

[Picture is of the lens - the black bits show the cortical cataract starting up]

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25
Q

Which age group does cortical cataract typically affect?

A

The 55-60 year old age group

26
Q

What does a cortical cataract in a young/younger Px indicate?

A

A metabolic disorder

27
Q

Where does Cortical catarct normally start and what may this suggest about its aetiology?

A

Two thirds of cases start in the lower nasal quadrant which may implicate UV in the aetiology

28
Q

What does direct illumination of a cortical cataract look like?

A
29
Q

The rate of progression of cortical cataract varies.

What must you do to make sure you don’t miss this kind of cataract?

A

You must look behind the iris in all positions ( using retro-illumination).

30
Q

In a cortical/cunieform cataract when are symptoms noticed?

A

Once cataract has progressed further than it should really.

[Look at slide for all the symptoms]

(only sometimes do you see astigmatism increase)

Patient will also complain of monocular diplopia - so diplopia in one eye. It is actually just a ghosting of images that is visible through one eye.

31
Q

Why is the Christmas tree cataract called the christmas tree cataract?

A

Because it has a polychromatic appearance (i.e. it has scatterings of different colours).

32
Q

Can a christmas tree cataract co-exist with another type of cataract?

A

Yes

33
Q

True or false - all types of cataract can co-exist with eachother?

A

True e.g. you could have nuclear sclerosis and PSC

34
Q

What are the effect on refractive error of the different types of cataract?

A
35
Q

What is pre-senile cataract?

A

A cataract that happens at a younger age.

36
Q

What is an example of a pre-senile cataract?

A

A diabetic cataract.

37
Q

What is a diabetic cataract also known as?

A

A snowflake cataract

38
Q

When does a traumatic cataract occur?

A

Following a direct injury to the crystalline lens.

39
Q

What happens in a traumatic cataract?

A

Injury to the lens ( concussion i.e. a violent shock from a heavy blow) causes an imprint of iris pigment on the anterior lens. This is called a ‘Vossius Ring’.

The cataract that follows is often star shaped as can be seen in the picture.

40
Q

In a traumatic cataract what are the effects on visual acuity dependant on?

A

The density of the cataract.

41
Q

What are at least three examples of drug induced cataract?

A
  • Steroid induced PSC cataract - this occurs from long term steroid use (topical or systemic).
  • Pigmented deposits in the lens as a result of Chlorpromazine which is an anti-psychotic drug.
  • Anterior Subcapsular cataract caused by Amiodarone - a drug taken for cardia arrhythmia
42
Q

What is the prevalence of congenital cataract?

A
43
Q

Can a congenital cataract cause a strabismus?

A

Yes - thats why babies’ eyes are screened within 72 hours of birth and again at six weeks - we look for a white pupil - also known as a leukorea.

44
Q

Can a congenital cataract be without a systemic association?

A

Yes it can be a result of a genetic mutation or idiopathic.

45
Q

Can a congenital cataract have a systemic association?

A

Yes it can be associated with:

  • Metabolic disorders e.g. rubella
  • Chromosomal abnormalities e.g. Down’s
46
Q

What are the different types of congenital cataracts discussed in the lecture?

A

Anterior Pole Cataract

Posterior Pole Cataract

Hereditory/genetic Congenital cataract

Idiopathic Cataract

47
Q

What does an anterior polar cataract look like?

A

•A White cone shaped opacity which is called a pyramidal

[looks like a stack of plates]

48
Q

What are the symptoms of anterior polar cataract and how does it affect VA?

A

No symptoms and it doesnt affect VA

49
Q

What is an anterior polar cataract associated with?

A

Persistent pupillary membrane

50
Q

What are the symptoms of Posterior Polar cataract similar to and what is posterior polar cataract associated with?

A
51
Q

What does a posterior polar cataract look like?

A
52
Q

What is Mittendorf’s dot and in whom is it typically seen?

A

Young Px with or without the association of cataract.

It is a remnant of the hyaloid artery.

53
Q

What are the three different types of hereditary cataract?

A

Zonular, Lamellar and Sutural.

54
Q

What do you need to know about lamellar cataract?

A
55
Q

What do you need to know about sutural cataract?

A
56
Q

Define Punctate

A

studded with or denoting dots or tiny holes.

57
Q

What are two examples of idiopathic cataract?

A

Blue dot cataract

Coronary cataract

58
Q

What do you need to know about Blue dot cataract?

A
59
Q

What do you need to know about a coronary cataract ?

A
60
Q

What is an example of a congenital cataract?

A
61
Q
A

Introduction to Eye Disease - Year 2 (40 decks)

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