Cataracts

• A cataract is an opacification or clouding of the lens. It is the most common cause of blindness worldwide.
• The lens helps to focus light onto the retina.

  There are three main anatomical structures of the lens relevant to cataracts:

  • Lens nucleus: middle aspect of the lens
  • Lens cortex: outer aspect of the lens
  • Lens capsule: the membrane surrounding the lens
• Three main types of cataracts:

  • Nuclear
  • Cortical
  • Posterior subcapsular
• Nuclear cataracts:

  • Sclerosis of the lens nucleus (middle)
  • Common in old age
  • Symptoms include myopia (short-sightedness) and colours appearing dull
• Cortical cataracts:

  • Opacifications of the lens cortex
  • On ophthalmoscopy the opacifications look like the spokes of a wheel around the edge of the lens
  • Vision is often unaffected
• Posterior subcapsular cataracts:

  • Opacifications in the posterior aspect of the lens capsule
  • Typically affects younger patients and people taking steroids
  • Patients complain of glare when looking at lights
  • Often progresses more rapidly than other types of cataracts
• Congenital cataracts:

  • Present from birth
  • associated with infection (congenital rubella syndrome)
  • Genetic predisposition
  • Often diagnosed during newborn examination due to absence of the fundal reflex
  • Urgent ophthalmology review / surgery to prevent amblyopia - permanent visual loss due to the brain neglecting the eye
• Most cataracts are associated with age-related changes.

  Other risk factors for cataracts include:

  • Diabetes
  • Steroid use
  • UV exposure
  • Smoking
  • Ocular trauma
  • Genetic predisposition
• Typical symptoms of cataracts include:

  • Progressive blurring of vision
  • Glare when looking at lights
  • Colours appearing dull
• Typical clinical findings on eye examination include:

  • Reduced red reflex (elicited by shining a light into the eye)
  • Clouded lens
• Conservative management:

  • Cataracts often begin small with mild symptoms and progress over several years.
  • NICE recommends refraining from surgical management until symptoms affect lifestyle.
  • Controlling risk factors such as diabetes, smoking, steroid use, and UV exposure may slow down the development of cataracts.
• Surgical management:

  • Phacoemulsification with an intraocular lens implant is the most common cataract surgery.
  • The opacified lens is broken down using ultrasound and the fragments are aspirated. A new lens is then implanted. This is often conducted under local anaesthetic.
• If not managed appropriately, cataracts can cause loss of vision.
• Complications following surgical management of cataracts include:

  • Posterior capsule opacification is common. Patients present months to years after cataract surgery complaining that it seems like their cataract is returning. It is treated with a capsulotomy, where lasers are used to make a hole in the capsule to allow light to pass through.
  • Endophthalmitis is an infection of the aqueous and/or vitreous humour. It is a rare, severe complication and can result in visual loss. Endophthalmitis is treated with intraocular antibiotic injections