What is a cataract and how is it managed?

Cataract: Definition and Management

A cataract is an opacification or clouding of the eye's natural lens that progressively impairs vision and requires surgical removal with artificial lens implantation as the only effective treatment. 1, 2

What is a Cataract?

Cataracts are characterized by:

• Definition: Opacity within the clear lens of the eye that interferes with visual function 1
• Prevalence: Leading cause of blindness worldwide, affecting approximately 50% of US adults 75 years or older 1
• Impact: Causes progressive deterioration in vision clarity, brightness, and contrast sensitivity 1

Types of Cataracts

The three most common types of cataracts are:

1. Nuclear Cataract:

   • Central opacification/discoloration of the lens
   • Progresses slowly
   • Affects distance vision more than near vision
   • May appear brunescent (brown) or opalescent (cloudy)

2. Cortical Cataract:

   • Can be central or peripheral
   • Appears as opaque spokes or oil droplets
   • Commonly causes glare symptoms
   • When entire cortex becomes white/opaque, it's called mature cortical cataract

3. Posterior Subcapsular Cataract (PSC):

   • Located just inside the posterior lens capsule
   • Causes substantial visual impairment if in the axial region
   • Patients experience glare and poor vision in bright light
   • Near vision typically more affected than distance vision
   • More common in younger patients than other types
   • Progresses more quickly than other types 1

Symptoms and Clinical Presentation

Patients with cataracts typically experience:

• Painless, progressive blurring of vision 3
• Decreased clarity and brightness of vision
• Glare disability, especially in bright light or while driving at night
• Myopic shift (increased nearsightedness)
• Changes in color perception
• Monocular diplopia (double vision in one eye) 4
• Reduced contrast sensitivity 1

Risk Factors

Major risk factors include:

• Age: Primary risk factor; risk increases with each decade after age 40 1, 3
• Genetics: Hereditary or genetic predisposition 3
• Medications: Corticosteroids (topical, periocular, oral, inhaled) 1, 3
• Trauma: Blunt or penetrating eye injuries 1
• Radiation: UV-B exposure, ionizing radiation 1
• Medical conditions: Uncontrolled diabetes, retinitis pigmentosa, Down syndrome 3
• Lifestyle factors: Smoking (dose-response effect for nuclear sclerosis) 1

Diagnosis

Cataracts are diagnosed through:

• Comprehensive eye examination by an ophthalmologist or optometrist
• Slit-lamp examination after pupillary dilation to classify opacities by anatomical distribution
• Assessment of visual function and impact on daily activities 1, 4

Management

Non-surgical Management

For early cataracts or when surgery is not immediately indicated:

• Refractive correction: Updated glasses or contact lens prescriptions to account for refractive shifts 1
• Low-vision devices: To maximize remaining vision pending surgery 1
• Lifestyle modifications:
  • Wearing brimmed hats and UV-B blocking sunglasses
  • Using safety glasses for high-risk activities
  • Smoking cessation 1

Note: There are currently no proven pharmacological treatments to eliminate existing cataracts or retard their progression 1

Surgical Management

Indications for Surgery:

Surgery is indicated when:

• Visual function declines and interferes with daily activities
• There is a reasonable likelihood of improvement with surgery
• The patient elects this option after being informed of risks and benefits 1, 2

Specific indications include:

• Best-corrected visual acuity of 20/40 or worse
• Clinically significant glare disability
• Clinically significant anisometropia
• Lens opacity interfering with management of posterior segment pathology
• Lens-induced inflammation or glaucoma 1, 2

Contraindications to Surgery:

• When tolerable refractive correction provides adequate vision
• When surgery is not expected to improve visual function
• When the patient cannot safely undergo surgery 1

Surgical Approach:

• Phacoemulsification: The gold standard procedure worldwide

  • Sutureless, small-incision technique
  • Performed on an outpatient basis
  • Includes foldable intraocular lens (IOL) implantation
  • Lower rate of surgical complications than other techniques
  • Enables astigmatism management and specialty IOL implantation 1, 2

• Manual small-incision cataract surgery (MSICS): Common in developing countries due to cost-effectiveness 1

Preoperative Assessment:

• Detailed assessment of visual acuity, refraction, intraocular pressure
• Evaluation of ocular comorbidities
• Biometry and IOL power calculation
• Assessment of systemic health issues that might affect surgery 2

Postoperative Care:

• Topical antibiotics and anti-inflammatory medications
• Regular follow-up to monitor for complications
• Management of residual refractive error 2

Potential Complications:

• Posterior capsule opacification
• Increased intraocular pressure
• Corneal edema
• Cystoid macular edema
• Endophthalmitis (reduced with intracameral antibiotics from 0.07% to 0.02%)
• Retinal detachment (especially in highly myopic patients) 2, 3

Outcomes

• Approximately 90% of patients report improved functional status and satisfaction with vision after cataract surgery 1, 2
• Benefits include improved visual acuity and contrast sensitivity, elimination of glare disability and halos, and enhanced night driving safety 2
• Bilateral cataract surgery provides superior binocular function compared to single-eye surgery 2
• Cataract surgery is associated with lower rates of falls (>30%) and dementia (20%-30%) 3

Special Considerations

• Most cataract operations are performed with topical anesthesia
• Patients do not require preoperative general medical testing
• Anticoagulants typically do not need to be discontinued
• Systemic α1-adrenergic antagonists (e.g., tamsulosin) may increase surgical complications 3
• Advanced technology IOLs (multifocal, accommodating) can reduce dependence on eyeglasses but may involve additional costs not covered by insurance 3