10 cataract facts

In this article we will describe 10 cataract facts.

A person with a cataract

Typical cataract

Key Points

  • Definition: A cataract is a opacification (clouding) of the lens in the eye, which can cause vision problems, and eventually blindness.
  • Prevalence: Cataracts are a leading cause of reversible blindness worldwide, especially common in older adults. According to the World Health Organisation (WHO), 35% of worldwide blindness is caused by cataracts – a figure that equates to around 20 million people.
  • Symptoms: Blurred vision, glare, and difficulty with night vision are classic symptoms.
  • Diagnosis: Primarily clinical, supported by slit-lamp examination.
  • Treatment: Surgical intervention, usually through phacoemulsification, is the most effective treatment.

1. Definition

  • A cataract is an opacity in the crystalline lens of the eye, leading to a decrease in visual acuity.
  • The lens, normally transparent, becomes clouded in cataracts, scattering light and reducing the clarity of images formed on the retina.
  • Cataracts are often age-related but may also be congenital or associated with other risk factors and conditions.
  • Three different types of cataract – nuclear sclerotic, cortical and posterior subcapsular.

2. Epidemiology

  • Cataracts are the primary cause of visual impairment in people aged 50 and over, accounting for roughly 35% of cases worldwide.
  • In the UK, the condition is prevalent, with an estimated 30% of people over 65 developing significant cataracts.
  • Due to an aging population, the incidence is expected to rise, increasing the demand for cataract surgery.

3. Risk Factors

  • Age: Cataracts are more common in individuals over 60.
  • Family History: Genetic predisposition can increase risk.
  • Lifestyle: Smoking, excessive alcohol consumption, and poor nutrition may contribute.
  • Environmental Factors: Long-term UV light exposure and occupational hazards like radiation.
  • Systemic Conditions: Diabetes, hypertension, and obesity are significant risk factors.
  • Medication: Long-term corticosteroid use is associated with increased cataract risk.

4. Causes

  • Cataracts occur when proteins in the lens degrade and clump together, creating opaque areas that distort vision.
  • This degeneration is often age-related but can also be accelerated by trauma, metabolic changes, or radiation exposure.
  • Congenital cataracts, though rare, can result from intrauterine infections, metabolic disorders, or genetic abnormalities.

5. Symptoms

Common symptoms of cataracts include:

  • Blurred Vision: Progressive blurring that worsens over time.
  • Glare and Halos: Particularly pronounced when looking at bright lights.
  • Colour Distortion: Colors may appear faded or yellowed.
  • Difficulty with Night Vision: Reduced vision in low-light conditions.
  • Double Vision: Often monocular (occurring in one eye only).

6. Diagnosis

Diagnosis of cataracts is based on clinical examination. Key diagnostic steps include:

  1. Patient History: Assessing for symptoms, risk factors, and impact on daily life.
  2. Visual Acuity Testing: Reduced visual acuity may suggest cataract progression.
  3. Slit-Lamp Examination: To directly assess the opacity and any other ocular abnormalities.
  4. Ophthalmoscopy: Often reveals difficulty in viewing the fundus in advanced cataracts.

Investigation

For most cases, clinical examination suffices. Additional investigations are rarely required but may include:

  • Optical Coherence Tomography (OCT): Useful if coexisting retinal pathology is suspected.
  • Tonometry: To rule out concurrent glaucoma.
  • Ultrasound B-scan: Indicated if a dense cataract obscures fundus details and posterior pathology is suspected.

Differential Diagnosis

The differential diagnosis for cataracts includes:

  • Age-related macular degeneration (AMD): Often presents with central vision loss.
  • Glaucoma: Chronic open-angle glaucoma may present with gradual vision loss.
  • Diabetic Retinopathy: Vision changes due to microvascular changes in diabetes.
  • Retinal Detachment: Presents with sudden vision loss and flashes/floaters.

7. Treatment

The mainstay of cataract treatment is surgical removal of the opacified lens, typically replaced by an intraocular lens (IOL) implant. The surgical options include:

  1. Phacoemulsification: Ultrasonic emulsification of the lens, the most common technique.
  2. Extracapsular Cataract Extraction (ECCE): A less common approach, generally reserved for very dense cataracts.

Most patients experience significant vision improvement post-surgery. Non-surgical management, such as stronger eyeglasses or magnification, may provide temporary benefit for those with mild cataracts.

8. Complications

While cataract surgery is generally safe, complications may arise, including:

  • Posterior Capsule Opacification (PCO): The most common complication, treatable with YAG laser capsulotomy.
  • Endophthalmitis: A rare but serious infection post-surgery.
  • Retinal Detachment: Slightly increased risk following surgery, especially in myopic patients.
  • Cystoid Macular Oedema (CME): Characterized by fluid accumulation in the macula, treated with anti-inflammatory medications.

9. Prognosis

  • With modern surgical techniques, the prognosis for patients undergoing cataract surgery is excellent.
  • Most regain significant visual acuity, enabling a return to daily activities.
  • However, pre-existing ocular or systemic conditions may influence the outcomes.

10. Prevention

Prevention strategies for cataracts include:

  • Lifestyle Modifications: Avoid smoking, limit alcohol intake, and ensure a balanced diet rich in antioxidants.
  • UV Protection: Wearing UV-blocking sunglasses to reduce cumulative UV exposure.
  • Regular Eye Examinations: Early detection of cataracts can allow for timely intervention.
  • Glycaemic Control in Diabetic Patients: Proper diabetes management reduces cataract risk.

Summary

We have described 10 cataract facts. We hope you understand them better now.