Cataracts

Question 1

What is the anatomy of the lens?

Answer 1

Note that the top of this picture represents anterior lens, and bottom represents posterior.

Question 2

What are cataracts?

Answer 2

Opacification of the crystalline lens leading to blindness

Question 3

What is the aetiology of cataracts? (x7)

Answer 3

• Normal ageing
• Trauma
• Metabolic disorders (hereditary or acquired): diabetes, parathyroid disorders, hypothyroidism, Wilson’s disease, hypocalcaemia, rubella, Down’s and many more
• Medications
• Congenital problems or congenital influences such as toxins
• Smoking
• UV radiation exposure.

Question 4

What is the pathophysiology of cataracts?

Answer 4

Changes in the lens proteins, called crystallins affects how the lens refracts light, affecting acuity. Chemical modification and formation of new cortical (outer layer) fibres leads to thickening, yellow-colouration, and hardening of the lens = nuclear sclerosis. Lens becomes stronger and this manifests as increasing myopia (far away objects are blurry) – see photo.

Question 5

What are the different types of cataract? (x6) Aetiology?

Answer 5

• Sclerotic: pathophysiology described above; opacification of nucleus of lens and age-related
• Cortical: opacification of the lens cortex
• Posterior/anterior sub-capsular: opacification of the posterior/anterior sub-capsular cortex. Associated with drugs and metabolic disorders, and trauma respectively.
• Cerulean: small and bluish opacity in lens cortex
• Snowflake: grey-white sub-capsular opacities associated with uncontrolled diabetes
• Sunflower: yellow/brown pigmentation of lens capsule in Wilson’s disease

Question 6

What is the epidemiology of cataracts: Common? Age? Gender?

Answer 6

Most common cause of reversible blindness. Associated with older age. More common in women.

Question 7

What are the signs and symptoms of cataracts? (x4 (x3))

Answer 7

• Slow decrease in vision, though some aetiologies such as diabetes might present with more sudden decreases
• Glare (described especially when driving at night)
• Washed-out colour vision (in nuclear cataracts, yellow changes to lens results in decreased richness of colours, especially blue)
• FUNDOSCOPY: Defects in red reflex, decrease in visual acuity that cannot be corrected by refractive correction, and an eye examination that reveals normal findings apart from opacity in crystalline lens.

Question 8

What are the investigations for cataracts?

Answer 8

Clinical diagnosis with fundoscopy including slit lamp examination of anterior chamber to visualise cataract.