1. Cataracts 1

Question 1

What is the definition of cataract?

Answer 1

Cataract is any opacity of the crystalline lens.

Question 2

Describe len anatomy in terms of vascularity, nerve innervation, structures (3), and cell types (2) and connection to other structures.

Answer 2

• Avascular
• Non-innervated
• Components: capsule, cortex with endothelium, nucleus
• Cell types: Cuboidal & Bow cells
• Connnected by zonules to ciliary body

Question 3

What are the 2 main functions of the ciliary body?

Answer 3

• Produce aqueous
• Acts as a muscle to focus the lens

Question 4

What is it called when the lens turns yellow?

Answer 4

Nucleosclerosis

Question 5

What proteins does a lens contain? What are their purposes?

Answer 5

30-70% protein.
* α, β = protective
* γ = clumping in nucleus hardening

Question 6

Describe the metabolism process that takes place in a len.

Answer 6

Anaerobic glycolysis occurs in the lens epithelium. This prodces energy needed for ion pumps, protein synthesis and to provide antioxidants (glutathione)

Question 7

How is fluid transported across the lens?

Answer 7

Water enters the lens via the thin posteiror capsule. Water is then pumped out of the anterior epithelium via Na+/K+-ATPase.

Question 8

Lens growth process
1. ... cells elongate and lose ... to form fibres.
2. Lens fibres elongate and meet at ..., forming: anterior suture (...) and posterior suture (...)
3. Continuous addition of ... to outer coat with age leads to increased ... with age. This increases ... with age and ... promotes cataract formation.
4. ... accumulate, causing yellowing
5. Expansion and aging cause ... thinning, which also causes increase in ... and cataract formation.

Answer 8

Lens growth process
1. Bow cells elongate and lose nucleus to form fibres.
2. Lens fibres elongate and meet at suture line, forming: anterior suture (Y) and posterior suture (inverted Y)
3. Continuous addition of fibres to outer coat with age leads to increased protein density with age. This increases refractive index with age and compression promotes cataract formation.
4. Chromophores accumulate, causing yellowing
5. Expansion and aging cause posterior capsule thinning, which also causes increase in fluid uptake and cataract formation.

Question 9

What is the commonest cause of blindness in non-western countries?

Answer 9

Cataract

Question 10

How does the prevalence of age-related cataract differ between race?

Answer 10

Indians have higher prevalence compared to Caucasians with age.

Question 12

What are the 4 types of cataracts? Which one is the most common?

Answer 12

• Artefacts
• Congenital - sight debilitating vs non-debilitating
• Acquired - induced/ toxic, secondary/ metabolic, trauma/ radiation
• Senile - PSC/ cortical/ nuclear [most common]

Question 13

What are the 3 types of anterior cataractous artefacts?

Answer 13

• Epicapsular stars
• Persistent pupillary membrane
• Leticonus (cone bulging of lens cortex & thining of capsule - associated w high myopia & Alport’s syndrome)

Question 14

What are the two types of posterior cataractous artefacts?

Answer 14

• Mittendorf dots (persistent hyaloid artery remnant)
• Nets or whorls (vitreous condensations)

Question 15

What are the 3 types of congenital cataracts?

Answer 15

• Sight debilitating
• Non-sight debilitating
• Associated w systemic disorder e.g. Galactosemia/ Rubella

Question 16

Which congenital cataract causes ‘oil droplet’ cataract? How is this confirmed?

Answer 16

Galactosemia.
Blood test for GL-1 kinase

Question 17

What type of cataract does congenital rubella cause?

Answer 17

Dense nuclear opacity

Question 18

How does a congenital axial or sutural cataract appear?

Answer 18

Chalky white clusters on or near suture line
May be polychromatic or sparkling with crystals

Question 19

How does a Cerulean congential cataract appear?

Answer 19

White to blue dots or spots in deep cortex, near the nucleus

Question 20

How do a pulverulent, zonular and coronary congenital cataract appear?

Answer 20

• Pulverulent - dense cataract located in embryonic nucleus
• Zonular is a ‘zone of cataract’ in outer nucleus
• Coronary is when zonular has riders = wedges/ lines into the cortex

Question 21

What are the common causes of acquired cataracts? (5)

Answer 21

• Corticosteroids (PSC)
• Tranquillisers/ Antipsychotics (Phenothiazine)
• Cholesterol-reducing drugs (Tiparanol)
• Miotics (1-2% Pilocarpine)
• Pesticides (Diquat)

Question 22

What are the 6 most important causes of secondary/ metabolic cataract?

Answer 22

• Diabetes (advanced senile changes; true diabetic cataract = snowflakes)
• Galactosemia
• Myotonic dystrophy
• Atopic dermatitis
• Various syndromes - Down’s, Marfan’s, Alport’s
• Associated with eye diseases - RP, uveitis, glaucoma

Question 23

What are the 4 major causes of traumatic/ radiation cataracts?

Answer 23

• Blunt injury
• Explosive injury
• Penetrating injury
• Radiating heat/ electrical shock e.g. glass blower cataract (large water vacuoles)

Question 24

How does trauma cause cataracts? Can these cataracts be reverse?

Answer 24

Trauma or FB triggers inflammation inside the eye and thus cause the formation of cataracts. Cataracts may have a variable time of onset after injury.
Early cataract changes may be reversed.

Question 25

What does SOAP stand for?

Answer 25

Subjective
Objective
Assessment
Plan

Question 26

What are the 3 subjective consequences of cataracts? Which type of cataract causes the most issues?

Answer 26

Cataract causes an altered refractive state in the lens, ∴
* Poor vision: VA, contrast, spatial frequency,
* Glare sensitivity
* Diplopia/ polyopia/ ghosting/ monocular diplopia

Worst in PSC as cataract is close to the nodal point

Question 27

What are the 4 methods for cataract detection?

Answer 27

• Red-reflex
• Direct illumination
• Indirect illumination - ‘ripples on beach’
• Specular reflection

Answer 28

Red reflex is formed by light refected from RPE/choroid. Therefore any opacities anterior to that can block light and form shadows.
Red reflex can be assessed using the ophthalmoscope or retinoscope. When moving your body, the relative motion of the corneal reflex to the shadow informs where the opacity lies.
* if with = behind nodal point (in vitreous)
* if against = in front of nodal point (in lens or AC)

Question 29

Which techniques allow you to cut through the lens like a knife? What are the other benefits of this technique?

Answer 29

Slit lamp
* Gives position and depth information - esp with narrow beam + large angles
* Can visualise the suture lines to define the nucleus

Question 30

Normal age changes to the lens isn’t a cataract until what happens?

Answer 30

It becomes a cataract when the age-related colour changes enter the nucleus of the lens

Question 31

Which 2 grading systems are commonly used to grade cataracts?

Answer 31

• LOCS-3 - uses comparative photos for grading
• Wisconsin - divide lens into 8 pie sectors: inner & outer zones. Record the number of segments with any cataract

Question 32

How will normal px response differ with high contrast vs low contrast Snellen charts? What about px with cataracts?

Answer 32

Normal px will drop 2 lines with low contrast vs high contrast.
Px with cataract will drop more than 2 lines with low contrast. They will also complain more about nighttime driving. Important t assess whether they are still legal to drive.