Summary

A cataract is an opacification of the crystalline lens of the eye, leading to visual impairment. It is the Leading Cause of Blindness Worldwide. The vast majority are age-related ("Senile"), caused by cumulative oxidative damage to lens proteins (crystallins). Patients present with gradual, painless deterioration of vision, often complaining of Glare (starbursts around lights) and difficulty reading. The condition is progressive but reversible. Surger is indicated when the visual impairment affects the patient's quality of life (e.g., losing driving licence). Phacoemulsification with Intraocular Lens (IOL) implantation is the gold standard procedure and is the most frequently performed surgery in the NHS.

Key Facts

• Prevalence: >50% of people over 80 have significant cataracts.
• Symptoms: Gradual painless loss of acuity, Glare, Myopic shift.
• Red Reflex: Reduced or absent (dark shadow).
• Steroids: Long-term systemic steroids cause Posterior Subcapsular Cataracts.
• Surgery: 95% success rate. Done under Local Anaesthetic.

Clinical Pearls

"Second Sight": Some elderly patients suddenly find they can read without their reading glasses! This is not a miracle; it is a Myopic Shift caused by Nuclear Sclerotic cataracts increasing the refractive index of the lens. They become more short-sighted (which helps near vision).

"Glare vs Blur": Posterior Subcapsular cataracts (common in diabetics/steroid users) cause disproportionate Glare (dazzle from headlights) compared to the reduced visual acuity. They sit right on the visual axis.

"The Post-Op Red Flag": If a patient calls 3 days after cataract surgery complaining of Pain and Blurring, this is Endophthalmitis (infection inside the eye). It is an ocular emergency requiring immediate intravitreal antibiotics to save sight.

"Leukocoria": A white pupil in a child is a Retinoblastoma until proven otherwise. Do not assume congenital cataract.

          PATIENT WITH GRADUAL VISION LOSS
                     ↓
        OPHTHALMOLOGY ASSMT (Slit Lamp)
                     ↓
      ┌──────────────┼───────────────┐
    MILD           MODERATE        SEVERE
  (VA 6/9,        (VA 6/12,       (VA <6/18,
   Happy)          Driving risk)   Struggling)
      ↓              ↓               ↓
  CONSERVATIVE    SURGERY         SURGERY
  (Update glass,  (Phaco + IOL)   (Phaco + IOL)
   Sunglasses)

1. Conservative

• Early cataracts do not need removal unless symptomatic.
• Refraction: Updating glasses prescription (to correct myopic shift) can buy time.
• Sunglasses: Reduce glare.

2. Surgical: Phacoemulsification

• Indication:
  • Vision affecting Quality of Life (Driving, Reading, Work).
  • Medical indication (Phacolytic glaucoma, need to view retina for diabetic laser).
• The Procedure:
  • Phaco: Ultrasound probe breaks up the lens ("eats it").
  • I&A: Cortex sucked out.
  • IOL: Foldable plastic lens injected into the empty capsular bag.
• Anaesthesia: Topical (Drops) or Sub-Tenon's (Block). Usually awake.

Intra-Operative

1. Posterior Capsule Rupture (PCR): The "Bag" breaks. Vitreous gel comes forward.
   • Risk: Retinal Detachment, Cystoid Macular Oedema.
   • Mx: Vitrectomy (cleanup), place lens in sulcus (if support remains).
2. Suprachoroidal Haemorrhage: Expulsive bleed. devastating.

Early Post-Op (<1 week)

1. Endophthalmitis: (1 in 1000).
   • Infection: Staph epidermidis/aureus.
   • Signs: Hypopyon (pus level), Paint, Vitreitis.
   • Mx: Tap (Biopsy) and Inject (Vancomycin/Ceftazidime).
2. Corneal Oedema: Trauma to endothelium.
3. Raised IOP: Retained viscoelastic gel.

Late Post-Op

1. Posterior Capsule Opacification (PCO):
   • Common (10-20%). Cell migration across the back of the IOL.
   • Sx: "The cataract has come back".
   • Tx: YAG Laser Capsulotomy (Simple 2 min laser procedure to blast a hole in the capsule).
2. Cystoid Macular Oedema (CMO).
3. Retinal Detachment.

Step-by-Step

1. Incisions: Clear corneal incision (2.4mm) and Paracentesis (side port).
2. Rhexis: Continuous Curvilinear Capsulorrhexis (CCC). Circular tear made in anterior capsule.
3. Hydrodissection: Water injected to separate lens from capsule. The lens should spin freely.
4. Phacoemulsification:
   • Groove: Crack the nucleus into 4 quadrants.
   • Chop/Eat: Ultrasound power emulsifies the hard nucleus.
5. Irrigation/Aspiration (I&A): Soft cortex vacuumed out. "Polishing" the bag.
6. Implantation: IOL injected. Unfolds in the bag.
7. Closure: Hydrate wounds (stromal hydration). No stitches usually needed.

"Measue Twice, Cut Once" Before surgery, we must choose the power of the lens (IOL).

• Biometry: Measures Axial Length (AL) and Corneal Curvature (K).
• Formulae: SRK/T, Barrett Universal II.
• Target:
  • Usually Emmetropia (Target 0 or -0.25 D) for distance. Patient wears reading glasses.
  • Monovision: One eye distance, one eye near.
  • Multifocal IOLs: Premium lenses (glasses independence) but risk of concentric glare/haloes.

A Cause of Amblyopia (Lazy Eye)

• If visual axis is blocked in a baby, the brain creates no pathways. The eye becomes legally blind (Amblyopia).
• Reflex: Check Red Reflex in all babies (NIPE check).
• Etiology:
  • Idiopathic.
  • TORCH Infections: Rubella, CMV, Toxoplasmosis.
  • Metabolic: Galactosaemia ("Oil droplet" cataract).
• Management: Urgent surgery (weeks) + Contact lenses (Growth of eye makes IOL sizing hard).

NICE NG77 (Cataracts)

• Do not restrict access based on Visual Acuity alone (e.g. "must be worse than 6/12").
• Decision based on impact on lifestyle.
• Prioritise "Second Eyes" (Binocular vision reduces falls).

ESCRS Guidelines

• Intracameral Cefuroxime (Antibotic in the eye at end of surgery) reduces Endophthalmitis rate by 5-fold.

What is a Cataract?

Inside your eye, there is a lens (like a camera lens) that focuses light. When you are young, it is clear. As you age, it becomes cloudy/frosted, like a dirty window. This is a cataract.

Can lasers remove it?

No. The only way to fix a cataract is surgery. We use ultrasound (sound waves) to break up the cloudy lens, suck it out, and replace it with a clear plastic lens. (Lasers are only used for "cleaning" the lens years after surgery if it hazes over).

Will I be asleep?

Usually not. We use strong anaesthetic drops to numb the eye. You are awake but feel no pain. The operation takes about 15-20 minutes.

Do I still need glasses?

Usually, yes. We aim to fix your distance vision (TV/Driving) so you don't need glasses for that. However, you will almost certainly need reading glasses for close work, as the plastic lens cannot change focus like a young natural lens.