Cataract

Introduction

Cataract is the opacification or clouding of the crystalline lens. It is the commonest cause of blindness and low vision in the world.

Aetiology

  • Congenital e.g. Rubella, Toxoplasmosis.
  • Developmental: Senile occurs with ageing
  • Secondary e.g. Traumatic, Diabetic,
  • Drug induced, post uveitic etc.

Clinical features

  • Gradual, painless loss of vision
  • In the early stages, it feels like looking through frosted glass.
  • If secondary, symptoms and signs of
    causative disease are also present.
  • Leukocoria (White pupillary reflex)

Differential diagnosis

  • Corneal opacity
  • Other causes of leucocoria e.g. Retinoblastoma (in children), retinal detachment, severe ocular toxoplasmosis etc.

Complications

  • In congenital cases, it can lead to amblyopia (lazy eye) if not operated early
  • Intumescent cataract with secondary glaucoma
  • Phacolytic uveitis and glaucoma

Investigations

  • Pupillary light reflex
  • Macular function test
  • Projection of light
  • Ocular ultrasounds scan: especially in cases of trauma to exclude pathology of the posterior segment of the eye

Management

Treatment objective –

  • To remove the cataractous lens
  • Replace with a clear plastic lens inserted into the eye (except in infants).

Main treatment

Surgical

  • An extracapsular cataract extraction with posterior chamber intraocular lens implant (ECCE + IOL) is the most appropriate for older children and adults.
  • Small incision cataract surgery and
    phacoemulsification are recent advances of the ECCE technique.
  • In new born babies and infants, a
    lensectomy and anterior vitrectomy is the preferred surgical procedure.
  • Aphakic glasses or contact lenses are worn to correct the resulting refractive error.
  • Posterior capsular opacity following ECCE could be treated with surgical or Yag laser capsulotomy.

Caution and contraindications to treatment

  • Intraocular lens implants is not advisable for new born babies and infants.

Prevention

  • Aspirin and other aspirin like analgesics have been found to delay cataracts in patients with diabetes and rheumatoid arthritis.
  • Antioxidant vitamins – Vitamin C has been found to have a protective effect against nuclear and posterior subcapsular cataracts.
  • Vitamin E has also been found to protect against nuclear and cortical cataract.