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Cataracts

Specialties > Ophthalmology

Background knowledge 🧠

Definition

  • Cataract is an opacity or clouding of the lens of the eye
  • Results in a decrease in vision, which can affect daily activities
  • Can occur in one or both eyes, but does not spread from one eye to the other

Epidemiology

  • Leading cause of blindness worldwide
  • More common with advancing age; prevalence increases significantly after age 65
  • Affects approximately 30% of those aged 65 and older in the UK
  • Risk factors include smoking, diabetes, and prolonged exposure to UV light

Aetiology and Pathophysiology

  • Ageing is the most common cause, due to protein changes in the lens
  • Secondary causes include diabetes, trauma, radiation, and corticosteroid use
  • Congenital cataracts may result from genetic factors, infections, or metabolic disorders
  • Pathophysiology involves the aggregation of lens proteins, leading to clouding

Types

  • Nuclear cataract: central lens opacification, often associated with ageing
  • Cortical cataract: involves the lens cortex, often spoked or wedge-shaped
  • Posterior subcapsular cataract: affects the back of the lens, common in diabetics and steroid users
  • Congenital cataract: present at birth, may be associated with other conditions

Clinical Features 🌡️

Symptoms

  • Gradual, painless loss of vision
  • Difficulty with night vision
  • Glare and halos around lights
  • Fading or yellowing of colours
  • Double vision in one eye (monocular diplopia)

Signs

  • Reduced visual acuity on Snellen chart
  • Loss of red reflex
  • Lens opacity visible on slit-lamp examination
  • May be associated with other eye conditions like glaucoma

Investigations 🧪

Tests

  • Slit-lamp examination to assess lens opacity
  • Visual acuity test (Snellen chart)
  • Dilated fundus examination to exclude other ocular conditions
  • Optical coherence tomography (OCT) if macular pathology is suspected
  • A-scan ultrasound to measure axial length before surgery

Management 🥼

Management

  • Surgical removal is the mainstay treatment (phacoemulsification with intraocular lens implant)
  • Surgery is indicated when cataract significantly impacts daily activities or vision
  • Non-surgical options (e.g., stronger glasses) are limited and usually temporary
  • Pre-operative assessment includes biometry, corneal topography, and discussion of risks
  • Post-operative care includes antibiotics and anti-inflammatory eye drops

Complications

  • Posterior capsular opacification (most common complication post-surgery)
  • Endophthalmitis (rare but serious)
  • Cystoid macular oedema
  • Retinal detachment
  • Intraoperative complications like zonular dehiscence

Prognosis

  • Generally excellent with over 95% of patients achieving improved vision post-surgery
  • Risks of surgery are low, but patient factors (e.g., comorbidities) can influence outcomes
  • Lifelong monitoring may be needed for complications such as posterior capsular opacification
  • Early detection and treatment generally lead to better outcomes

Key Points

  • Cataracts are a common, treatable cause of visual impairment, particularly in the elderly
  • Surgery is effective and safe, with a high success rate
  • Regular eye examinations are crucial for early detection and management
  • Patient education about the symptoms and progression of cataracts is important
  • Managing risk factors (e.g., diabetes control, smoking cessation) can delay progression

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Ophthalmology