D - Cataracts 1 - Week -3

Question 1

State the 3 components of the lens

Answer 1

Capsule
Cortex with endothelium
Nucleus

Question 2

What two cell types exist within the lens?

Answer 2

Cuboidal cells
Bow cells

Question 3

Describe the composition of the lens

Answer 3

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

Question 4

Which lens crystalin is formed foetally?

Answer 4

Gamma

Question 5

What is the proposed role of alpha and beta crystalin?

Answer 5

Protective

Question 6

Which crystalline clumps in association with nucleus hardening?

Answer 6

Gamma

Question 7

Describe the metabolism of the lens

Answer 7

Anaerobic glycolysis in epithelium.

Question 8

What is produced from lens metabolism and why?

Answer 8

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

Question 9

How does fluid flux occur through the lens?

Answer 9

Water enters lens via thin posterior capsule
Pumped out of anterior epithelium with NA/K/ATPase

Question 10

Where do lens fibres meet?

Answer 10

At suture lines

Question 11

What are lens fibres made up of?

Answer 11

Bow cells which have elongated and lost their nucleus

Question 12

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

Answer 12

Anteriorly: a Y
Posteiorly: an upside down Y

Question 13

What causes the yellowing of the lens with age?

Answer 13

Accumulation of chromophores

Question 14

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

Answer 14

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

Question 15

What are the 4 general types of cataracts?

Answer 15

Artefacts
Congenital
Acquired
Senile

Question 16

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

Answer 16

Sight debilitating
Non-sight debilitating = most common

Question 17

What 3 types of anterior cateractous artefacts are there?

Answer 17

Epicapsular stars
Persistant pupillary membrane
Lenticonus

Question 18

What secondary conditions is lenticonus associated with?

Answer 18

High myopia
Alport’s syndrome

Question 19

What are the 2 types of posterior cateractous artifacts?

Answer 19

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

Question 20

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

Answer 20

Rubella
Galactosemia
Need GP or paediatrician for blood work up

Question 21

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

Answer 21

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

Question 22

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

Answer 22

Large mittendorf dots (remnant mesodermal vascular tissue)
Small-large obstruction close to nodal point

Question 23

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

Answer 23

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

Question 24

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

Answer 24

<1/12: 60%
<3/12: 20%

Question 25

Name 5 types of non-debilitating congenital cataracts

Answer 25

Axial Sutural Cerulean Coronary Pulverulent

Question 26

Describe a cerulean cataract

Answer 26

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

Question 27

Describe a coronary cataract

Answer 27

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

Question 28

Describe a pulverulent cataract

Answer 28

A dense cataract located in embryonic nucleus

Question 29

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

Answer 29

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

Question 30

What are zonular cataracts?

Answer 30

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]

Question 31

What kind of cataracts can be zonular?

Answer 31

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

Question 32

What is the most common type of zonular cataract?

Answer 32

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

Question 33

What are Zonular/Lamellar cataracts?

Answer 33

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.

Question 34

Name the most common causes of acquired cataracts (6)

Answer 34

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

Question 35

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

Answer 35

Prednisolone. Cataract forms at the back by the nodall point

Question 36

List the 6 most important causes of secondary/metabolic cataracts

Answer 36

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)

Question 37

List 4 causes of traumatic cataract

Answer 37

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

Question 38

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

Answer 38

Subluxation of the lens with tearing of zonules

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

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

Answer 41

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)

Question 42

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

Answer 42

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