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Cataracts

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Overview

Cataracts are characterised by the gradual opacification of the cornea, leading to difficulties with vision. The most common cause of cataracts is increasing age. Cataracts can be acquired or congenital. Congenital cataracts tend to be bilateral and symmetrical.

Epidemiology

  • Incidence increases with age
  • Cataracts are uncommon in children
  • Cataracts are the leading cause of curable vision loss globally

Risk Factors and Associations

Presentation

Patients often have a gradual decrease in vision with the patient being unaware until it becomes significant enough for them to notice. Other features are:

  • Blurred/cloudy vision
  • Glare around lights
    • Often patients have difficulties driving at night
  • Washed-out colour vision
    • Colours appear more faded out
  • Defects in the red reflex
    • This is due to the opacity preventing light from getting to the retina
  • Halos around lights

Differential Diagnoses

Age-related macular degeneration (AMD)

  • Central vision is either blurry/distorted
  • Fundoscopy may show signs such as drusen (dry AMD), or neovascularisation (wet AMD)

Primary open-angle glaucoma

  • Insidious loss of peripheral vision – “tunnel vision”
  • Intraocular pressure increased
  • Fundoscopy shows an increased cup-to-disc ratio

Retinal detachment

  • Onset of vision loss is acute
  • Flashes of light and floaters followed by a “curtain” coming over the vision
  • Fundoscopy may show detachment

Vitreous haemorrhage

  • Onset of vision loss is acute
  • There may be a history of trauma or poorly-controlled diabetes
  • There may be a vision haze or a red colour to the vision

Investigations

  • Fundoscopy:
  • Measurement of intraocular pressure:
    • To rule out glaucoma, should be normal
  • Slit-lamp examination
    • Shows cataract

Management

  • In early stages: conservative management e.g. stronger glasses/contact lenses
  • Consider surgery based on patient preferences – there is no threshold of visual acuity at which surgery is indicated.

Patient Advice

  • Patients should be safety-netted on signs of complications and should seek immediate help if they have any visual changes
  • Patients should have information about eyedrops, when to get new glasses and how to do so, and who to contact if they have any concerns

Complications

Cataract complications

  • Functional blindness
    • Removal of the cataract returns vision, provided there are no other disease processes taking place

Surgery complications

  • Posterior capsular opacification
    • Due to the proliferation of remaining lens epithelial cells
    • Can lead to decreased visual acuity/blurred vision/glare
    • Can be corrected with laser treatment 
  • Posterior capsule rupture with or without vitreous loss

Prognosis

  • With surgery, around 95% of patients will have 6/12 vision provided no other eye disease processes are taking place
  • Untreated cataracts in children <10 years of age may lead to amblyopia and subsequent lifelong visual impairment even if the cataracts are removed.

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