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Senile (Age-Related) Cataract

Definition

Lens Anatomy (Relevant to Understanding Cataract)

Fig. 10.1 - (A) Cross-sectional anatomy of the anterior segment; (B) histological cross-section showing zones of the lens

• Zonules hold the lens in position
• Capsule - an acellular membrane enclosing the lens
• Epithelial cells - cuboid cells beneath the anterior capsule; cells in the germinative zone divide continuously and differentiate into lens fibres
• Lens substance - a central nucleus surrounded by cortical material

Effect on Vision

Types of Age-Related Cataract

Fig. 10.2 - (A) Posterior subcapsular; (B) Posterior subcapsular on retroillumination showing Wedl cells (arrow); (C) Nuclear sclerosis; (D) Nuclear sclerosis on retroillumination showing nucleus-cortex demarcation (arrow); (E) Cortical cataract; (F) Cortical spokes on retroillumination; (G) Christmas tree cataract; (H) Christmas tree on retroillumination

1. Posterior Subcapsular Cataract (PSC)

• Lies just in front of the posterior capsule
• Granular or plaque-like on oblique slit lamp
• Appears black and vacuolated on retroillumination
• Vacuoles are swollen migratory lens epithelial cells - called bladder cells or Wedl cells (similar to those in posterior capsular opacification)
• Due to location at the nodal point of the eye, even a small PSC has a profound effect on vision
• Patients are troubled by glare (e.g. from oncoming headlights)
• Symptoms worsen with miosis (near tasks, bright sunlight)

2. Nuclear Sclerotic Cataract

• An exaggeration of normal ageing change
• Associated with myopia due to increased refractive index of nucleus - results in "second sight of the aged" (elderly patients can read without glasses again)
• Characterized by a yellowish hue due to deposition of urochrome pigment
• Best assessed with an oblique slit lamp beam
• Retroillumination shows good red reflex but subtle nucleus-cortex demarcation
• When advanced: nucleus appears brown (brunescent), and in rare cases black (nigra)

3. Cortical Cataract

• Involves anterior, posterior or equatorial cortex
• Opacities begin as clefts and vacuoles between lens fibres due to cortical hydration
• Progress to typical cuneiform (wedge-shaped) or radial spoke-like opacities
• Often initially in the inferonasal quadrant
• Glare is a common symptom (as with PSC)

4. Christmas Tree Cataract

• Polychromatic, needle-like crystalline deposits in the lens
• Creates a multicoloured sparkling appearance (like a Christmas tree)
• Seen on direct illumination and retroillumination (panels G and H above)

Cataract Maturity (Stages)

Associated Risk Factors / Cataract in Systemic Disease

Diabetes Mellitus

• Hyperglycaemia raises aqueous glucose → enters lens → converted to sorbitol by aldose reductase → osmotic overhydration
• Refractive fluctuations follow plasma glucose level (hyperglycaemia = myopia)
• Classic snowflake cortical opacity - rare, seen in young diabetics; can mature within days or resolve spontaneously
• Age-related cataract occurs earlier in diabetics; nuclear sclerosis common and rapidly progressive
• ~1 in 5 cataract surgery patients have diabetes

Other systemic associations

• Chronic steroid use (posterior subcapsular)
• Myotonic dystrophy
• Neurofibromatosis type 2
• Down syndrome
• Galactosaemia (in children)

Secondary (Complicated) Cataract

• Chronic anterior uveitis - most common cause; both inflammation and steroid treatment are causative; earliest sign is polychromatic lustre at posterior pole
• Acute angle closure glaucoma - produces small grey-white subcapsular opacities called glaukomflecken (focal infarcts of lens epithelium; pathognomonic)
• High myopia - posterior subcapsular opacity + early nuclear sclerosis
• Hereditary fundus dystrophies (retinitis pigmentosa, Leber congenital amaurosis, gyrate atrophy, Stickler syndrome) - usually posterior subcapsular opacity

Management

When to Operate

• The cataract significantly impairs the patient's quality of life or ability to carry out daily tasks
• There is a secondary complication (e.g. phacomorphic or phacolytic glaucoma)

Surgical Options

1. Phacoemulsification (Standard procedure)

• Standard method in high-income countries and most regional centres worldwide
• Ultrasonic probe emulsifies and aspirates lens material through a small self-sealing incision (~2.4-2.8 mm)
• Followed by insertion of a foldable intraocular lens (IOL)
• Advantages: small incision, rapid recovery, low astigmatism

2. Manual Extracapsular Cataract Extraction (ECCE)

• Larger incision; nucleus expressed intact
• Used where phaco is unavailable or for very hard (brunescent) nuclei

3. Intracapsular Cataract Extraction (ICCE)

• Entire lens including capsule removed
• Largely obsolete; still used in some resource-limited settings

Intraocular Lens (IOL)

• Implanted in the capsular bag after lens removal
• Calculated using biometry (A-scan ultrasound or optical coherence-based measurement)
• Types include monofocal, multifocal, toric (for astigmatism correction)

Preoperative Considerations

• Record systemic medications - especially alpha-blockers (e.g. tamsulosin) which cause Intraoperative Floppy Iris Syndrome (IFIS)
• Manage anticoagulants per local protocol
• Check for allergy (iodine, latex, antibiotics)
• Assess for MRSA carriage
• Ophthalmic assessment: VA, pupil responses (cataract never causes RAPD - if present, suspect posterior pole pathology), corneal endothelial count, IOP, fundus

Key Points to Remember (High-Yield for Exams)

1. Most common cause of reversible blindness worldwide
2. No medical treatment prevents cataract
3. PSC - worst visual impact per unit of opacity (at nodal point); worst with miosis
4. Nuclear sclerosis - causes myopia ("second sight"), yellow/brown hue, urochrome deposition
5. Cortical - spoke-like opacities, starts inferonasally
6. Morgagnian cataract - liquefied cortex with sunken nucleus (hypermature stage)
7. Glaukomflecken - pathognomonic of previous acute angle closure
8. "Second sight of the aged" - nuclear myopia allowing reading without glasses
9. Phacoemulsification is the gold standard surgery
10. Tamsulosin (alpha-blocker) - causes IFIS during phaco surgery

• Title page with source citation (Kanski's Clinical Ophthalmology, 10th Ed.)
• Lens anatomy diagram (Fig. 10.1)
• Full slit-lamp photo grid of all cataract types (Fig. 10.2)
• Symptoms table
• All 4 types of age-related cataract with bullet points
• Cataract maturity stages table (Immature → Morgagnian)
• Cataract in systemic disease (Diabetes + others)
• Secondary cataract causes table
• Management - surgical methods comparison table
• Preoperative considerations
• High-yield exam points summary table