Cataract

Question 1

What is cataracts?

Answer 1

• commonest cause of preventable blindness
• health economics a major factor
• it is clouding of natural (crystalline) lens due to precipitation of proteins
• RFs → age, steroids (systemic/topical), diabetes

Question 2

What are the clinical features of cataracts?

Answer 2

• blurring, haze, dazzle of bright lights (esp when driving at night)
• affects near (reading) and distance (TV) equally
• washed-out colour vision
• usually both eyes but one can be more advanced
• fields + pupils normal
• may be defects in red reflex

Question 3

What investigations can be done for cataracts?

Answer 3

• dilated fundus examination → fundus + optic nerve normal
• measurement of intra-ocular pressure → normal or elevated if glaucoma
• glare vision test → reduced visual acuity under conditions of glare stress
• slit lamp examination of anterior chamber → cataract visible

Question 4

The simple presence of a lens opacity or cataract on its own is not an indication for intervention. Treatment is indicated if:

• Cataract is causing other ocular diseases
• Opacification is sufficiently dense, despite best-spectacle correction, to cause functional impairment of the patient’s vision
• Opacification is sufficiently dense to preclude visualisation of the ocular fundus in the setting of active posterior segment disease or planned posterior segment surgery

What is the treatment for cataracts?

Answer 4

• opt for surgery when it’s affecting life enough to justify small risk of surgery
• surgery involves fragmenting + aspirating the cataractous lens
• plastic lens → intra-ocular lens inserted in its place
• done under local anaesthetic
• 1 in 1000 risk severe, permanent sight loss (endophthalamitis, macular oedema, retinal detachment)
• 1 in 10 need laser surgery later for opacification of tissue behind the inttra-ocular lens (posterior capsule)