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OD3 - Clin. Optometry Sem 1 and Preacademic Period > D - Cataracts 1 - Week -3 > Flashcards

D - Cataracts 1 - Week -3 Flashcards

1
Q

State the 3 components of the lens

A

Capsule
Cortex with endothelium
Nucleus

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2
Q

What two cell types exist within the lens?

A

Cuboidal cells

Bow cells

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3
Q

Describe the composition of the lens

A

40-70% water
2-3% salt
30-70% protein

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4
Q

Which lens crystalin is formed foetally?

A

Gamma

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5
Q

What is the proposed role of alpha and beta crystalin?

A

Protective

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6
Q

Which crystalline clumps in association with nucleus hardening?

A

Gamma

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7
Q

Describe the metabolism of the lens

A

Anaerobic glycolysis in epithelium.

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8
Q

What is produced from lens metabolism and why?

A

Energy: for Ion pumps, protein synthesis
Glutathione: an antioxidant

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9
Q

How does fluid flux occur through the lens?

A

Water enters lens via thin posterior capsule

Pumped out of anterior epithelium with NA/K/ATPase

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10
Q

Where do lens fibres meet?

A

At suture lines

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11
Q

What are lens fibres made up of?

A

Bow cells which have elongated and lost their nucleus

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12
Q

What does the lens suture look like anteriorly? And posteriorly?

A

Anteriorly: a Y
Posteiorly: an upside down Y

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13
Q

What causes the yellowing of the lens with age?

A

Accumulation of chromophores

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14
Q

How does ageing affect the lens? (Other than yellowing) What does this result in?

A

Posterior capsule thinning. Leads to increased fluid uptake and cataract formation

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15
Q

What are the 4 general types of cataracts?

A

Artefacts
Congenital
Acquired
Senile

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16
Q

What types of congenital cataracts are there? (2) Which is most common?

A

Sight debilitating

Non-sight debilitating = most common

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17
Q

What 3 types of anterior cateractous artefacts are there?

A

Epicapsular stars
Persistant pupillary membrane
Lenticonus

18
Q

What secondary conditions is lenticonus associated with?

A

High myopia

Alport’s syndrome

19
Q

What are the 2 types of posterior cateractous artifacts?

A 
Mittendorf dot (break off of posterior hyaloid artery)
Nets or whorls (vitreous condensations)
20
Q

What systemic disorders can be associated with congenital cataract? (2). What should you do in these cases?

A

Rubella
Galactosemia
Need GP or paediatrician for blood work up

21
Q

What is a general rule for the association between cataract position and vision?

A

Generally, the closer the cataract is to the posterior of the lens, the greater the effect on vision

22
Q

How does a posterior polar cataract present in anterior examination? (2)

A

Large mittendorf dots (remnant mesodermal vascular tissue)

Small-large obstruction close to nodal point

23
Q

How does a cataract associated with Galactosemia present in anterior examination? How about in blood test?

A

Oil droplet cataract

Blood test reveals reduction in galactokinase (GL-1 kinase)

24
Q

What percentage of rubella cataracts are sight debilitating if <1/12 gestation at time of inoculation? What about <3/12?

A

<1/12: 60%

<3/12: 20%

25
Q

Name 5 types of non-debilitating congenital cataracts

A 
Axial
Sutural
Cerulean
Coronary
Pulverulent
26
Q

Describe a cerulean cataract

A

Blue dots/opacities in deep lens cortex (near nucleus)

27
Q

Describe a coronary cataract

A

Is a zonular/lamellar cataract that has “riders” (i.e. radial wedges of opacity) going into the cortex

28
Q

Describe a pulverulent cataract

A

A dense cataract located in embryonic nucleus

29
Q

How do axial or sutural cataracts present on anterior eye examination?

A

Chalky white clusters on/near the suture line. May be polychromatic/sparkling (crystals)

30
Q

What are zonular cataracts?

A

cataracts where only a region or “zone” of the lens is opaque. i.e. an opacity localized in a specific lenticular region [from webvision, so I know it’s legit]

31
Q

What kind of cataracts can be zonular?

A

Any. Providing they only affect one particular region of the lens

32
Q

What is the most common type of zonular cataract?

A

Lamellar cataract. Hence why often used interchangeably with zonular despite being a subtype.

33
Q

What are Zonular/Lamellar cataracts?

A

A congenital cataract in which opacity is limited to layers of the lens external to the nucleus. Aka “perinuclear” (next to the nucleus). Aka lens cortex for instance.

34
Q

Name the most common causes of acquired cataracts (6)

A

Corticosteroids (PSC)
Tranquillisers/antipsychotics (phonothiazine)
Some Cholesterol reducing drugs (Tiparanol)
Miotics
Pesticides
Many other drugs

35
Q

Give an example of a common corticosteroid that can cause acquired cataract. Where would the cataract form?

A

Prednisolone. Cataract forms at the back by the nodall point

36
Q

List the 6 most important causes of secondary/metabolic cataracts

A

Diabetes - the only one we’ll really see
Galactosemiai
Myotonic dystrophy
Atopic dermatitis
Various syndromes (down’s, marfan’s, alports)
Assoc. with eye disease (RP, uveitis, glaucom)

37
Q

List 4 causes of traumatic cataract

A

Blunt injury (most common. Sports)
Explosive injury
Penetrating injury (e.g. nail gun)
Radiating heat/electrical shock

38
Q

What might happen to the lens with severe trauma? What does this involve?

A

Subluxation of the lens with tearing of zonules

39
Q

How can a cataract affect a patient subjectively? (3)

A

Poor vision: low contrast, facial recognition, reading
Glare sensitivity
Diplopia/polyopia

40
Q

What forms the red reflex? How might opacities affect this?

A

light reflected from RPE/choroid. Opacities block the light to form shadows

41
Q

How do you check the location of an opacity when looking at the red reflex?

A

Using an ophthalmoscope:
If with movement: opacity behind nodal point (in vitreous)
If against movement: opacity in front of nodal point (i.e. in lens or AC)

42
Q

How can you get an idea of opacity depth in a slit lamp?

A

view with a slit/narrow beam. Slit gives cross section of the tissue

OD3 - Clin. Optometry Sem 1 and Preacademic Period (25 decks)

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