Cataract

 

• Background

  Pathophysiology

  • Opacification of lens, usually due to age-related pigment build-up.
  • Leads to ↓transparency and ↓refractive index of lens, and hence visual impairment.

  Causes of premature cataracts

  • Steroids, including topical therapy near eyes.
  • Congenital: trisomy, myotonic dystrophy, infection (rubella, HSV).
  • Ocular disease: glaucoma, severe myopia, retinal detachment.
  • Diabetes
  • UV or infrared radiation.

  Epidemiology

  • Extremely common: 30% prevalence over age 65, and 60% over 80.

• Signs and symptoms

  Symptoms:

  • Blurred vision and gradual ↓acuity, with difficulty reading, watching TV, and recognising faces.
  • Glare from bright lights.
  • Monocular diplopia.
  • Loss of stereopsis if unilateral.

  Signs:

  • Reduced red reflex.
  • Clouded lens.

• Investigations

  Clinical diagnosis. Can be supported by slit lamp with dilated pupil, but not obligatory.

• Management

  Non-surgical

  • Conservative treatment is often appropriate initially, as cataracts has a highly varied rate of progression, with significant impairment often taking many years to develop.
  • Advise not to drive and to contact the DVLA if there is difficulty reading a number plate from 20 metres.

  Surgical

  Indications:

  • When symptoms restrict lifestyle including driving, reading etc.

  Procedure:

  • Phacoemulsification: lens broken up with ultrasound and aspirated from the eye. It is an extracapsular extraction i.e. lens removed but lens capsule left in place.
  • Intraocular lens implant inserted into remaining capsule.
  • Done under local anaesthetic in around 20 minutes.

  Complications:

  • Perioperative: haemorrhage, local anaesthetic-related, vitreous loss.
  • Early post-op: endophthalmitis, anisometria, eye or eyelid bruising.
  • Late post-op (months later): posterior capsular opacification causing blurred vision (common), retinal detachment.

  Outcome:

  • Improves visual acuity, though reading glasses usually needed afterwards.